阅读说明：本技术 自行车链轮 (Bicycle chain wheel ) 是由 杉本明信 于 2017-11-20 设计创作，主要内容包括：一种自行车链轮,包括链轮主体、多个链轮齿、至少一个换档促进突起和至少一个凸起部分。至少一个换档促进突起构造为在自行车链条从自行车链轮朝向较小链轮换挡的第一换档操作中与自行车链条接合。至少一个凸起部分沿驱动旋转方向设置在至少一个换档促进突起的下游侧上,自行车链轮在蹬踏期间沿驱动旋转方向旋转。至少一个凸起部分与至少一个换档促进突起间隔开等于或小于两个链条节距的距离。(A bicycle sprocket includes a sprocket body, a plurality of sprocket teeth, at least one shift facilitating protrusion, and at least one raised portion. The at least one shift facilitating protrusion is configured to engage the bicycle chain in a first shifting operation in which the bicycle chain is shifted from the bicycle sprocket toward the smaller sprocket. The at least one raised portion is disposed on a downstream side of the at least one shift facilitating protrusion in a driving rotation direction in which the bicycle sprocket rotates during pedaling. The at least one raised portion is spaced from the at least one shift facilitating protrusion by a distance equal to or less than two chain pitches.)

1. A bicycle sprocket comprising:

A sprocket body;

A plurality of sprocket teeth disposed on an outer edge of the sprocket body;

At least one shift facilitation zone that facilitates at least one of a first shift operation and a second shift operation,

In the first shifting operation, the bicycle chain is shifted from the bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in an axial direction parallel to a rotational center axis of the bicycle sprocket, no additional sprocket between the bicycle sprocket and the smaller sprocket, and

In the second shifting operation, the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket; at least one drive facilitation zone; and

At least one raised portion having a contact surface configured to move the bicycle chain toward the smaller sprocket in the second shifting operation, the at least one raised portion being disposed in the at least one drive promoting region.

2. the bicycle sprocket as in claim 1, wherein

The plurality of sprocket teeth comprise

At least one first tooth having a first chain engagement width defined along the axial direction, an

At least one second tooth having a second chain engagement width defined along the axial direction that is less than the first chain engagement width, and

The at least one raised portion is disposed on a downstream side of one of the at least one first tooth in a drive rotation direction in which the bicycle sprocket rotates during pedaling.

3. The bicycle sprocket as in claim 2, wherein

The first chain engagement width is greater than an inner chain space defined between the pair of opposing inner link plates of the bicycle chain and less than an outer chain space defined between the pair of opposing outer link plates of the bicycle chain, an

The second chain engagement width is less than the inner chain space.

4. The bicycle sprocket as in claim 1, wherein

The plurality of sprocket teeth comprise

A reference tooth having a reference tooth center plane defined as a maximum axial width bisecting the reference tooth in the axial direction, an

An offset tooth having an offset tooth center plane defined as bisecting a maximum axial width of the offset tooth in the axial direction, the offset tooth center plane being offset from the reference tooth center plane of the reference tooth in the axial direction toward the smaller sprocket, and

The at least one raised portion is disposed on a downstream side of the offset tooth in a drive rotation direction in which the bicycle sprocket rotates during pedaling.

5. A bicycle sprocket comprising:

A sprocket body;

A plurality of sprocket teeth disposed on an outer edge of the sprocket body;

At least one shift facilitating protrusion configured to engage a bicycle chain in a first shift operation in which the bicycle chain is shifted from the bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in an axial direction parallel to a rotational center axis of the bicycle sprocket without an additional sprocket between the bicycle sprocket and the smaller sprocket; and

At least one raised portion disposed on a downstream side of the at least one shift facilitating protrusion in a driving rotation direction in which the bicycle sprocket rotates during pedaling, the at least one raised portion having a contact surface configured to move the bicycle chain toward the smaller sprocket.

6. The bicycle sprocket as in claim 5, wherein

The contact surface is configured to guide the bicycle chain toward the smaller sprocket.

Technical Field

The present invention relates to a bicycle sprocket.

Background

Bicycling is becoming an increasingly popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One bicycle component that has been extensively redesigned is a sprocket.

Disclosure of Invention

In accordance with a first aspect of the present invention, a bicycle sprocket comprises a sprocket body, a plurality of sprocket teeth, at least one shift facilitating protrusion, and at least one raised portion. A plurality of sprocket teeth are disposed on an outer edge of the sprocket body. The at least one shift facilitating protrusion is configured to engage a bicycle chain in a first shift operation in which the bicycle chain is shifted from a bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in an axial direction parallel to a rotational center axis of the bicycle sprocket without an additional sprocket between the bicycle sprocket and the smaller sprocket. The at least one raised portion is disposed on a downstream side of the at least one shift facilitating protrusion in a driving rotation direction in which the bicycle sprocket rotates during pedaling. The at least one raised portion is spaced from the at least one shift facilitating protrusion by a distance equal to or less than two chain pitches.

With the bicycle sprocket according to the first aspect, the at least one shift facilitating protrusion allows the bicycle chain to smoothly shift from the bicycle sprocket toward the smaller sprocket in the first shifting operation. Further, the at least one raised portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be smoothly shifted between the bicycle sprocket and the smaller sprocket.

According to a second aspect of the present invention, the bicycle sprocket according to the first aspect is configured such that the at least one raised portion has a contact surface configured to move the bicycle chain toward the smaller sprocket.

With the bicycle sprocket according to the second aspect, it is possible to surely reduce interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be smoothly shifted between the bicycle sprocket and the smaller sprocket.

According to a third aspect of the present invention, the bicycle sprocket according to the first or second aspect is configured such that the at least one raised portion is configured to limit engagement of the at least one shift facilitating protrusion with the bicycle chain in at least one of a first shift operation and a second shift operation in which the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket.

With the bicycle sprocket according to the third aspect, it is possible to shift the bicycle chain between the bicycle sprocket and the smaller sprocket more smoothly in at least one of the first and second shifting operations.

According to a fourth aspect of the present invention, the bicycle sprocket according to any one of the first to third aspects is configured such that the at least one projecting portion is spaced apart from the at least one shift facilitating protrusion by a distance equal to or less than one chain pitch.

With the bicycle sprocket according to the fourth aspect, it is possible to surely reduce interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a fifth aspect of the present invention, the bicycle sprocket according to any one of the first to fourth aspects is configured such that the at least one projecting portion is at least partially disposed radially inward of the at least one shift facilitating protrusion with respect to the rotational center axis.

With the bicycle sprocket according to the fifth aspect, the at least one projecting portion and the at least one shift facilitating protrusion may be arranged along a chain line of the bicycle chain when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket, the interference between the bicycle chain and the at least one shift facilitating protrusion can be reduced with certainty. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a sixth aspect of the present invention, the bicycle sprocket according to any one of the first to fifth aspects is configured such that the plurality of sprocket teeth includes a reference tooth having a reference tooth center plane defined as a maximum axial width that bisects the reference tooth in the axial direction. The at least one shift facilitating protrusion has a first axial height defined in an axial direction from the reference tooth center plane. The at least one raised portion has a second axial height defined in the axial direction from the reference tooth center plane, the second axial height being greater than the first axial height.

With the bicycle sprocket according to the sixth aspect, it is possible to surely reduce interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a seventh aspect of the present invention, the bicycle sprocket according to any one of the second to sixth aspects is configured such that the plurality of sprocket teeth includes a reference tooth having a reference tooth center plane defined as a maximum axial width that bisects the reference tooth in the axial direction. The contact surface has a radially outer end and a radially inner end. An axial distance is defined in the axial direction between the contact surface and the reference tooth center plane. The contact surface is inclined to increase the axial distance from the radially outer end to the radially inner end.

With the bicycle sprocket according to the seventh aspect, the contact surface allows the bicycle chain to smoothly move away from the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to an eighth aspect of the present invention, the bicycle sprocket according to the seventh aspect is configured such that the radially outer end portion is at least partially disposed on a downstream side of the radially inner end portion in the driving rotation direction.

With the bicycle sprocket according to the eighth aspect, the direction in which the contact surface extends can be arranged along the direction in which the at least one protruding portion and the bicycle chain relatively move when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket, the bicycle chain can be smoothly moved away from the at least one shift facilitating protrusion. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a ninth aspect of the present invention, the bicycle sprocket according to the seventh or eighth aspect is configured such that the radially outer end portion has a first width. The radially inner end portion has a second width less than the first width.

With the bicycle sprocket according to the ninth aspect, the contact surface allows the bicycle chain to more smoothly move away from the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a tenth aspect of the present invention, the bicycle sprocket according to any one of the seventh to ninth aspects is configured such that an angle defined between the contact surface and the reference tooth center plane of the reference tooth is equal to or less than 50 degrees.

With the bicycle sprocket according to the tenth aspect, the contact surface allows the bicycle chain to more smoothly move away from the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to an eleventh aspect of the present invention, the bicycle sprocket according to any one of the seventh to tenth aspects is configured such that an angle defined between the contact surface and the reference tooth center plane of the reference tooth is equal to or less than 45 degrees.

With the bicycle sprocket according to the eleventh aspect, the contact surface allows the bicycle chain to more smoothly move away from the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

According to a twelfth aspect of the present invention, the bicycle sprocket according to any one of the first to eleventh aspects is configured such that the plurality of sprocket teeth includes at least one first tooth having a first chain engagement width defined in the axial direction and at least one second tooth having a second chain engagement width defined in the axial direction. The second chain engagement width is less than the first chain engagement width. The at least one shift facilitating protrusion is at least partially disposed closer to the central axis of rotation than the at least one first tooth. One of the at least one first tooth is at least partially disposed closest to the at least one shift facilitating protrusion in the at least one first tooth.

With the bicycle sprocket according to the twelfth aspect, the at least one first tooth improves chain retention performance of the bicycle sprocket. Furthermore, the interference between the bicycle chain and the at least one first tooth having a larger width can be reduced. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

In accordance with a thirteenth aspect of the present invention, the bicycle sprocket according to the twelfth aspect is configured such that the first chain engagement width is greater than an inner chain space defined between the pair of opposing inner link plates of the bicycle chain and less than an outer chain space defined between the pair of opposing outer link plates of the bicycle chain. The second chain engagement width is less than the inner chain space.

With the bicycle sprocket according to the thirteenth aspect, the at least one first tooth further improves chain retention performance of the bicycle sprocket.

In accordance with a fourteenth aspect of the present invention, the bicycle sprocket according to any one of the first to thirteenth aspects is configured such that the plurality of sprocket teeth includes at least one first tooth having a first chain engagement width defined in the axial direction and at least one second tooth having a second chain engagement width defined in the axial direction. The second chain engagement width is less than the first chain engagement width. The at least one raised portion is at least partially disposed closer to the central axis of rotation than the at least one second tooth. One of the at least one second tooth is at least partially disposed closest to the at least one raised portion in the at least one second tooth.

With the bicycle sprocket according to the fourteenth aspect, the at least one first tooth improves chain retention performance of the bicycle sprocket. Further, interference between the at least one raised portion and a bicycle chain engaged with the bicycle sprocket can be reduced. Therefore, the chain holding performance of the bicycle sprocket can be effectively improved.

In accordance with a fifteenth aspect of the present invention, the bicycle sprocket according to the fourteenth aspect is configured such that the first chain engagement width is greater than an inner chain space defined between an opposing pair of inner link plates of the bicycle chain and less than an outer chain space defined between an opposing pair of outer link plates of the bicycle chain. The second chain engagement width is less than the inner chain space.

With the bicycle sprocket according to the fifteenth aspect, the at least one first tooth further improves chain retention performance of the bicycle sprocket.

According to a sixteenth aspect of the present invention, the bicycle sprocket according to any one of the first to fifteenth aspects is configured such that the plurality of sprocket teeth includes a first derailing tooth provided on an outer edge of the sprocket body to first disengage the bicycle chain from the bicycle sprocket in a first shifting operation. The at least one raised portion is at least partially disposed closer to the central axis of rotation than the first derailing tooth. The first derailing tooth is at least partially disposed closest to the at least one raised portion in the plurality of sprocket teeth.

With the bicycle sprocket according to the sixteenth aspect, the at least one projecting portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion or reduces interference between the bicycle chain and the at least one projecting portion when the bicycle chain disengages from the bicycle sprocket at the first derailleurs.

According to a seventeenth aspect of the present invention, the bicycle sprocket according to the sixteenth aspect is configured such that the plurality of sprocket teeth further includes a second derailing tooth provided on an outer edge of the sprocket body to first disengage the bicycle chain from the bicycle sprocket in a third shifting operation in which the bicycle chain is shifted from the bicycle sprocket toward the smaller sprocket. The third shift operation is different from the first shift operation in a chain phase of the bicycle chain. The second derailing tooth is disposed on a downstream side of the first derailing tooth in the driving rotation direction. At least one raised portion is at least partially disposed between the first and second derailing teeth in a circumferential direction defined about the central axis of rotation.

With the bicycle sprocket according to the seventeenth aspect, the at least one raised portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain disengages from the bicycle sprocket at the second derailleurs. Therefore, the chain holding performance of the bicycle sprocket can be effectively improved.

According to an eighteenth aspect of the present invention, a bicycle sprocket comprises a sprocket body, a plurality of sprocket teeth, at least one shift facilitating protrusion, and at least one raised portion. A plurality of sprocket teeth are disposed on an outer edge of the sprocket body. The plurality of sprocket teeth includes a reference tooth having a reference tooth center plane defined as a maximum axial width bisecting the reference tooth in an axial direction parallel to a rotational center axis of the bicycle sprocket. The at least one shift facilitating protrusion is configured to engage a bicycle chain in a first shift operation in which the bicycle chain is shifted from a bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in the axial direction without an additional sprocket between the bicycle sprocket and the smaller sprocket. The at least one shift facilitating protrusion has a first axial height defined in an axial direction from a reference tooth center plane of the reference tooth. The at least one raised portion is disposed on a downstream side of the at least one shift facilitating protrusion in a driving rotation direction in which the bicycle sprocket rotates during pedaling. At least one of the raised portions has a contact surface. The contact surface includes a radially outer end and a radially inner end. An axial distance is defined in the axial direction between the contact surface and the reference tooth center plane. The contact surface is inclined to increase the axial distance from the radially outer end to the radially inner end. The at least one raised portion has a second axial height defined in the axial direction from a reference tooth center plane of the reference tooth. The second axial height is greater than the first axial height.

With the bicycle sprocket according to the eighteenth aspect, the at least one shift facilitating protrusion allows the bicycle chain to smoothly shift from the bicycle sprocket toward the smaller sprocket in the first shifting operation. Further, the at least one raised portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be smoothly shifted between the bicycle sprocket and the smaller sprocket.

In accordance with a nineteenth aspect of the present invention, a bicycle sprocket comprises a sprocket body, a plurality of sprocket teeth, at least one shift facilitating area, at least one drive facilitating area, and at least one raised portion. A plurality of sprocket teeth are disposed on an outer edge of the sprocket body. The at least one shift facilitation zone facilitates at least one of a first shift operation in which the bicycle chain is shifted from the bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in an axial direction parallel to a rotational center axis of the bicycle sprocket without an additional sprocket therebetween and a second shift operation in which the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. The at least one raised portion has a contact surface configured to move the bicycle chain toward the smaller sprocket in the second shifting operation. At least one raised portion is disposed in the at least one drive promoting region.

With the bicycle sprocket according to the nineteenth aspect, the at least one raised portion reduces interference between the bicycle chain and one of the plurality of sprocket teeth when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be smoothly shifted from the smaller sprocket toward the bicycle sprocket.

In accordance with a twentieth aspect of the present invention, the bicycle sprocket according to the nineteenth aspect is configured such that the plurality of sprocket teeth includes at least one first tooth having a first chain engagement width defined in the axial direction and at least one second tooth having a second chain engagement width defined in the axial direction, the second chain engagement width being less than the first chain engagement width. The at least one raised portion is disposed on a downstream side of one of the at least one first tooth in a driving rotation direction in which the bicycle sprocket rotates during pedaling.

With the bicycle sprocket according to the twentieth aspect, the at least one first tooth improves chain retention performance of the bicycle sprocket while the at least one raised portion reduces interference between the bicycle chain and one of the plurality of sprocket teeth when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket.

In accordance with a twenty-first aspect of the present invention, the bicycle sprocket according to the twentieth aspect is configured such that the first chain engagement width is greater than an inner chain space defined between the pair of opposing inner link plates of the bicycle chain and less than an outer chain space defined between the pair of opposing outer link plates of the bicycle chain. The second chain engagement width is less than the inner chain space.

With the bicycle sprocket according to the twenty-first aspect, the at least one first tooth further improves chain retention performance of the bicycle sprocket.

According to a twenty-second aspect of the present invention, the bicycle sprocket according to any one of the nineteenth to twenty-first aspects is configured such that the plurality of sprocket teeth includes a reference tooth having a reference tooth center plane defined to bisect the maximum axial width of the reference tooth in the axial direction, and an offset tooth having an offset tooth center plane defined to bisect the maximum axial width of the offset tooth in the axial direction. The offset tooth center plane is offset in an axial direction from the reference tooth center plane of the reference tooth toward the smaller sprocket. At least one raised portion is disposed on a downstream side of the offset teeth in a driving rotation direction in which the bicycle sprocket rotates during pedaling.

With the bicycle sprocket according to the twenty-second aspect, the at least one raised portion reduces interference between the bicycle chain and the offset teeth when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket.

According to a twenty-third aspect of the present invention, a bicycle sprocket comprises a sprocket body, a plurality of sprocket teeth, at least one shift facilitating protrusion, and at least one raised portion. A plurality of sprocket teeth are disposed on an outer edge of the sprocket body. The at least one shift facilitating protrusion is configured to engage a bicycle chain in a first shift operation in which the bicycle chain is shifted from the bicycle sprocket toward a smaller sprocket adjacent to the bicycle sprocket in an axial direction parallel to a rotational center axis of the bicycle sprocket without an additional sprocket between the bicycle sprocket and the smaller sprocket. The at least one raised portion is disposed on a downstream side of the at least one shift facilitating protrusion in a driving rotation direction in which the bicycle sprocket rotates during pedaling. The at least one raised portion has a contact surface configured to move the bicycle chain toward the smaller sprocket.

With the bicycle sprocket according to the twenty-third aspect, the at least one shift facilitating protrusion allows the bicycle chain to smoothly shift from the bicycle sprocket toward the smaller sprocket in the first shifting operation. Further, the at least one raised portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be smoothly shifted between the bicycle sprocket and the smaller sprocket.

In accordance with a twenty-fourth aspect of the present invention, the bicycle sprocket according to the twenty-third aspect is configured such that the contact surface is configured to guide a bicycle chain toward the smaller sprocket.

with the bicycle sprocket according to the twenty-fourth aspect, the contact surface of the at least one raised portion reduces interference between the bicycle chain and the at least one shift facilitating protrusion when the bicycle chain is shifted from the smaller sprocket toward the bicycle sprocket. Thus, the bicycle chain can be shifted more smoothly between the bicycle sprocket and the smaller sprocket.

Drawings

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 is a side elevational view of a bicycle crank assembly that includes a bicycle sprocket in accordance with a first embodiment.

FIG. 2 is another side elevational view of the bicycle crank assembly illustrated in FIG. 1.

FIG. 3 is a perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 4 is another perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 5 is a side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 6 is a cross sectional view of the bicycle sprocket taken along the line VI-VI in FIG. 5.

FIG. 7 is a cross sectional view of the bicycle sprocket taken along the line VII-VII in FIG. 5.

FIG. 8 is a side elevational view of the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

Fig. 9 is a cross-sectional view of the smaller sprocket taken along line IX-IX in fig. 8.

FIG. 10 is a cross-sectional view of the smaller sprocket taken along line X-X in FIG. 8.

FIG. 11 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 12 is a partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 13 is another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 14 is a cross sectional view of the bicycle sprocket taken along line XIV-XIV in FIG. 11.

FIG. 15 is an enlarged, partial side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 16 is a cross sectional view of the bicycle sprocket taken along line XVI-XVI in FIG. 11.

FIG. 17 is another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1.

FIG. 18 is a cross sectional view of the bicycle sprocket taken along line XVIII-XVIII in FIG. 11.

FIG. 19 is a cross sectional view of the bicycle sprocket with the bicycle chain (second shift operation) taken along line XIX-XIX of FIG. 11.

FIG. 20 is a partial perspective view of the bicycle sprocket illustrated in FIG. 5.

FIG. 21 is another partial perspective view of the bicycle sprocket illustrated in FIG. 5.

FIG. 22 is a cross sectional view of the bicycle sprocket illustrated in FIG. 19 with the bicycle chain (first shift operation or state where the bicycle chain is engaged with the bicycle sprocket).

FIG. 23 is a plan view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (first shifting operation).

FIG. 24 is a cross sectional view of the bicycle sprocket illustrated in FIG. 16 with the bicycle chain (first shift operation).

FIG. 25 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (first shifting operation).

FIG. 26 is a plan view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (second shifting operation).

FIG. 27 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (second shifting operation).

FIG. 28 is a cross sectional view of the bicycle sprocket illustrated in FIG. 16 with the bicycle chain (second shifting operation).

FIG. 29 is a cross sectional view of the bicycle sprocket illustrated in FIG. 14 with the bicycle chain (second shifting operation).

FIG. 30 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (second shifting operation).

FIG. 31 is a plan view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 1 with the bicycle chain (second shifting operation).

FIG. 32 is a side elevational view of the bicycle crank assembly that includes the bicycle sprocket in accordance with the second embodiment.

FIG. 33 is a perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32.

FIG. 34 is a side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 32.

FIG. 35 is a cross sectional view of the bicycle sprocket taken along line XXXV-XXXV in FIG. 34.

FIG. 36 is a cross sectional view of the bicycle sprocket taken along line XXXVI-XXXVI in FIG. 34.

FIG. 37 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (first chain phase state).

FIG. 38 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (third chain phase state).

FIG. 39 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (second chain phase state).

FIG. 40 is a partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32.

FIG. 41 is another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32.

FIG. 42 is still another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32.

FIG. 43 is a plan view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (first shifting operation).

FIG. 44 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (first shifting operation).

FIG. 45 is a plan view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (third shift operation).

FIG. 46 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (third shift operation).

FIG. 47 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 32, with the bicycle chain (second shifting operation).

FIG. 48 is a side elevational view of a bicycle crank assembly that includes the bicycle sprocket in accordance with the third embodiment.

FIG. 49 is a side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 48.

FIG. 50 is a cross sectional view of the bicycle sprocket taken along the line L-L in FIG. 49.

FIG. 51 is a side elevational view of a bicycle crank assembly that includes the bicycle sprocket in accordance with the fourth embodiment.

FIG. 52 is a side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 51.

FIG. 53 is a cross sectional view of the bicycle sprocket taken along the line LIII-LIII in FIG. 52.

FIG. 54 is a cross sectional view of the bicycle sprocket taken along the line LIV-LIV in FIG. 52.

FIG. 55 is a side elevational view of the smaller sprocket of the bicycle crank assembly illustrated in FIG. 51.

Fig. 56 is a cross-sectional view of the smaller sprocket taken along line LVI-LVI in fig. 51.

Fig. 57 is a cross-sectional view of the smaller sprocket taken along line LVII-LVII in fig. 51.

Fig. 58 is a cross-sectional view of the smaller sprocket taken along line LVIII-LVIII in fig. 51.

FIG. 59 is a partial side elevational view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 51.

FIG. 60 is a cross-sectional view of the smaller sprocket taken along line LX-LX in FIG. 59.

FIG. 61 is a partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 51.

FIG. 62 is another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 51.

FIG. 63 is yet another partial perspective view of the bicycle sprocket and the smaller sprocket of the bicycle crank assembly illustrated in FIG. 51.

FIG. 64 is a cross-sectional view of the smaller sprocket taken along line LXIV-LXIV in FIG. 59.

FIG. 65 is a cross-sectional view of the smaller sprocket taken along line LXV-LXV in FIG. 59.

FIG. 66 is a side elevational view of the bicycle crank assembly that includes the bicycle sprocket in accordance with the fifth embodiment.

FIG. 67 is a side elevational view of the bicycle sprocket of the bicycle crank assembly illustrated in FIG. 66.

FIG. 68 is a cross sectional view of the bicycle sprocket taken along line LVIII-LVIII in FIG. 67.

Detailed Description

Embodiments will now be described with reference to the drawings, wherein like reference numerals designate corresponding or identical elements throughout the various views.

first embodiment

Referring initially to fig. 1 and 2, a bicycle crank assembly 10 is illustrated that includes a bicycle sprocket 12 in accordance with a first embodiment. The bicycle crank assembly 10 includes a smaller sprocket 14, a crank axle 16, a crank arm 18 and an additional crank arm 20. The crank arm 18 is a right crank arm. The additional crank arm 20 is a left crank arm. The crank arm 18 and the additional crank arm 20 are fixed to the crank axle 16.

In this application, the following directional terms "forward", "rearward", "left", "right", "lateral", "upward" and "downward", as well as any other similar directional terms, refer to those directions as determined by a user (e.g., a rider) seated on a bicycle's seat (not shown) facing a handlebar (not shown). Accordingly, these terms, as utilized to describe the bicycle sprocket 12 should be interpreted relative to a bicycle equipped with the bicycle sprocket 12 as used in an upright riding position on a horizontal surface.

As seen in fig. 1 and 2, the bicycle sprocket 12 has a center axis of rotation a1 and is rotatable about a center axis of rotation a1 with respect to a bicycle frame (not shown). Specifically, the bicycle crank assembly 10 is rotatable relative to the bicycle frame about a center axis of rotation a 1. During pedaling, the bicycle sprocket rotates about the center axis of rotation a1 in a driving rotational direction D11. The drive rotational direction D11 is defined along a circumferential direction D1 defined about the rotational center axis a 1.

The bicycle sprocket 12 and the smaller sprocket 14 engage the bicycle chain C to transmit the rotational driving force F1 to the bicycle chain C. The bicycle chain C is shifted between the smaller sprocket 14 and the bicycle sprocket 12 by a front derailleur (not shown). In the present embodiment, the bicycle sprocket 12 is a front sprocket. However, at least one of the structures of the bicycle sprocket 12 can be at least partially applied to a rear sprocket.

The bicycle sprocket 12 is coupled to the crank arm 18 to rotate integrally with the crank arm 18 about the rotational center axis a 1. The smaller sprocket 14 is coupled to the crank arm 18 to rotate integrally with the crank arm 18 about the rotational center axis a 1. In the present embodiment, the bicycle crank assembly 10 includes a sprocket mounting member 24. The sprocket mounting member 24 is mounted on the crank arm 18 so as to be integrally rotatable with the crank arm 18 about the rotational center axis a 1. The bicycle sprocket 12 and the smaller sprocket 14 are coupled to the sprocket mounting member 24. The sprocket mounting member 24 includes a crank connecting arm 26. The smaller sprocket 14 includes a first crank attachment portion 28. The bicycle sprocket 12 includes a second crank attachment portion 29. The crank connecting arms 26 are fastened to the first crank attachment portions 28 with fasteners such as bolts (not shown), respectively. The second crank attachment portion 29 is fastened to the sprocket mounting member 24 with a fastener such as a bolt (not shown).

In the present embodiment, the sprocket mounting member 24 and the crank arm 18 are integrally provided as a one-piece, unitary member. However, the sprocket mounting member 24 can be a separate member from the crank arm 18. Furthermore, the sprocket mounting member 24 can be omitted from the bicycle crank assembly 10. In such embodiments, the smaller sprocket 14 and the bicycle sprocket 12 can be directly coupled to the crank arm 18 and the crank axle 16. The sprocket mounting member 24 can be integrally provided with one of the bicycle sprocket 12, the smaller sprocket 14 and the crank axle 16.

As seen in fig. 3 and 4, the bicycle crank assembly 10 includes a bicycle sprocket 12 and a smaller sprocket 14. However, the bicycle crank assembly 10 can include at least three sprockets. The smaller sprocket 14 is adjacent the bicycle sprocket 12 in an axial direction D2 that is parallel to the rotational center axis a1 with no additional sprocket between the smaller sprocket 14 and the bicycle sprocket 12.

As seen in fig. 5, the bicycle sprocket 12 includes a sprocket body 30 and a plurality of sprocket teeth 32. A plurality of sprocket teeth 32 are disposed on an outer edge 30A of the sprocket body 30. The plurality of sprocket teeth 32 includes at least one first tooth 34 and at least one second tooth 36. The sprocket body 30 can also be referred to as a first sprocket body 30. The plurality of sprocket teeth 32 may also be referred to as a plurality of first sprocket teeth 32. At least one first tooth 34 is provided on the outer edge 30A to engage the bicycle chain C. At least one second tooth 36 is provided on the outer edge 30A to engage the bicycle chain C. In the present embodiment, the at least one first tooth 34 includes a plurality of first teeth 34 disposed on the outer edge 30A to engage the bicycle chain C. The at least one second tooth 36 includes a plurality of second teeth 36 disposed on the outer edge 30A to engage the bicycle chain C. The plurality of first teeth 34 and the plurality of second teeth 36 are alternately arranged in the circumferential direction D1.

In the present embodiment, as seen in FIG. 6, the bicycle sprocket 12 includes a first axial surface 38 and a first opposing axial surface 40. The first axial surface 38 faces the smaller sprocket 14 in an axial direction D2 that is parallel to the rotational center axis a 1. The first opposing axial surface 40 faces the axial direction D2 and is disposed on an opposite side of the first axial surface 38 in the axial direction D2. The sprocket body 30 has a first body maximum width W10 defined between the first axial surface 38 and the first counter axial surface 40 in the axial direction D2. The sprocket body 30 has a first reference center plane CP10, the first reference center plane CP10 being defined as bisecting the first body maximum width W10 in the axial direction D2. The first reference center plane CP10 is perpendicular to the rotational center axis a 1.

As shown in fig. 6, the at least one first tooth 34 has a first chain engagement width W11 defined along the axial direction D2. In this embodiment, the first tooth 34 includes a first chain engagement surface 34A and a first additional chain engagement surface 34B. The first link engaging surface 34A faces in the axial direction D2 and is contactable with a bicycle chain C (e.g., an outer link plate C2). The first additional chain engagement surface 34B faces the axial direction D2 and is disposed on an opposite side of the first chain engagement surface 34A along the axial direction D2. The first additional link engaging surface 34B is contactable with a bicycle chain C (e.g., an outer link plate C2). A first chain engagement width W11 is defined between the first chain engagement surface 34A and the first additional chain engagement surface 34B in the axial direction D2.

The first tooth 34 has a first center plane CP11 defined as a first center plane CP11 that bisects the first chain engagement width W11 in the axial direction D2. The first center plane CP11 is perpendicular to the center axis of rotation a 1. The first center plane CP11 is offset from the first reference center plane CP10 in the axial direction D2. However, the first center plane CP11 may coincide with the first reference center plane CP10 in the axial direction D2. The first teeth 34 have a symmetrical shape with respect to the first center plane CP11 along the axial direction D2. However, the first teeth 34 may have an asymmetric shape with respect to the first center plane CP11 along the axial direction D2.

As shown in fig. 7, the at least one second tooth 36 has a second chain engagement width W12 defined along the axial direction D2. In this embodiment, the second tooth 36 includes a second chain engagement surface 36A and a second additional chain engagement surface 36B. The second chain engagement surface 36A faces in the axial direction D2 and is contactable with a bicycle chain C (e.g., an inner link plate C1). The second additional chain engagement surface 36B faces the axial direction D2 and is disposed on an opposite side of the second chain engagement surface 36A along the axial direction D2. The second additional link engaging surface 36B is contactable with a bicycle chain C (e.g., an inner link plate C1). A second chain engagement width W12 is defined between the second chain engagement surface 36A and the second additional chain engagement surface 36B in the axial direction D2.

The second tooth 36 has a second center plane CP12, the second center plane CP12 defined to bisect the second chain engagement width W12 in the axial direction D2. The second center plane CP12 is perpendicular to the center axis of rotation a 1. The second center plane CP12 is offset from the first reference center plane CP10 in the axial direction D2. However, the second center plane CP12 may coincide with the first reference center plane CP10 in the axial direction D2. The second central plane CP12 coincides with the first central plane CP 11. However, the second center plane CP12 may be offset from the first center plane CP11 in the axial direction D2. The second tooth 36 has a symmetrical shape with respect to the second center plane CP12 in the axial direction D2. However, the second teeth 36 may have an asymmetric shape with respect to the second center plane CP12 along the axial direction D2.

In the present embodiment, the second chain engagement width W12 is smaller than the first chain engagement width W11. The first chain engagement width W11 is greater than an inner chain space C11 defined between the pair of opposing inner link plates C1 of the bicycle chain C and less than an outer chain space C21 defined between the pair of opposing outer link plates C2 of the bicycle chain C. The second chain engagement width W12 is less than the inner chain space C11. However, the second chain engagement width W12 may be equal to or greater than the first chain engagement width W11. The first chain engagement width W11 may be less than the inner chain space C11.

As shown in FIG. 8, the smaller sprocket 14 includes a second sprocket body 42 and a plurality of second sprocket teeth 44. A plurality of second sprocket teeth 44 are disposed on an outer edge 42A of the second sprocket body 42. The plurality of second sprocket teeth 44 includes at least one third tooth 46 and at least one fourth tooth 48. At least one third tooth 46 is provided on the outer edge 42A to engage the bicycle chain C. At least one fourth tooth 48 is provided on the outer edge 42A to engage the bicycle chain C. In the present embodiment, the at least one third tooth 46 includes a plurality of third teeth 46 disposed on the outer edge 42A to engage the bicycle chain C. The at least one fourth tooth 48 includes a plurality of fourth teeth 48 disposed on the outer edge 42A to engage the bicycle chain C. The plurality of third teeth 46 and the plurality of fourth teeth 48 are alternately arranged in the circumferential direction D1.

In the present embodiment, as shown in FIG. 9, the smaller sprocket 14 includes a second axial surface 50 and a second opposing axial surface 52. The second axial surface 50 faces the axial direction D2. The second opposing axial surface 52 faces the bicycle sprocket 12 in the axial direction D2 and is disposed on an opposite side of the second axial surface 50 in the axial direction D2. The second sprocket body 42 has a second body maximum width W20 defined between the second axial surface 50 and the second counter axial surface 52 in the axial direction D2. The second sprocket body 42 has a second reference center plane CP20 defined as a second body maximum width W20 that is bisected by the second reference center plane CP20 in the axial direction D2. The second reference center plane CP20 is perpendicular to the rotational center axis a 1.

As shown in fig. 9, the at least one third tooth 46 has a third chain engagement width W21 defined along the axial direction D2. In this embodiment, the third tooth 46 includes a third chain engagement surface 46A and a third additional chain engagement surface 46B. The third link engagement surface 46A faces in the axial direction D2 and is contactable with a bicycle chain C (e.g., an outer link plate C2). The third additional chain engagement surface 46B faces the axial direction D2, and is disposed on an opposite side of the third chain engagement surface 46A in the axial direction D2. The third additional link engaging surface 46B is contactable with a bicycle chain C (e.g., an outer link plate C2). A third chain engagement width W21 is defined between the third chain engagement surface 46A and the third additional chain engagement surface 46B in the axial direction D2.

The third tooth 46 has a third center plane CP21 defined as a third center plane CP21 that bisects the third chain engagement width W21 in the axial direction D2. The third center plane CP21 is perpendicular to the center axis of rotation a 1. The third center plane CP21 is offset from the second reference center plane CP20 in the axial direction D2. However, the third center plane CP21 may coincide with the second reference center plane CP20 in the axial direction D2. The third teeth 46 have a symmetrical shape with respect to the third center plane CP21 along the axial direction D2. However, the third teeth 46 may have an asymmetric shape with respect to the third center plane CP21 along the axial direction D2.

As shown in fig. 10, the at least one fourth tooth 48 has a fourth chain engagement width W22 defined along the axial direction D2. In this embodiment, the fourth tooth 48 includes a fourth chain engagement surface 48A and a fourth additional chain engagement surface 48B. The fourth link engaging surface 48A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., an inner link plate C1). The fourth additional chain engagement surface 48B faces the axial direction D2 and is disposed on an opposite side of the fourth chain engagement surface 48A along the axial direction D2. The fourth additional link engaging surface 48B is contactable with a bicycle chain C (e.g., an inner link plate C1). A fourth chain engagement width W22 is defined between the fourth chain engagement surface 48A and the fourth additional chain engagement surface 48B in the axial direction D2.

The fourth tooth has a fourth center plane CP22, the fourth center plane CP22 defined to bisect the fourth chain engagement width W22 in the axial direction D2. The fourth center plane CP22 is perpendicular to the center axis of rotation a 1. The fourth center plane CP22 is offset from the second reference center plane CP20 in the axial direction D2. However, the fourth center plane CP22 may coincide with the second reference center plane CP20 in the axial direction D2. The fourth central plane CP22 coincides with the third central plane CP 21. However, the fourth center plane CP22 may be offset from the third center plane CP21 in the axial direction D2. The fourth teeth 48 have a symmetrical shape with respect to the fourth center plane CP22 along the axial direction D2. However, the fourth teeth 48 may have an asymmetric shape with respect to the fourth center plane CP22 along the axial direction D2.

In the present embodiment, the fourth chain engagement width W22 is smaller than the third chain engagement width W21. The third chain engagement width W21 is greater than an inner chain space C11 defined between the pair of opposing inner link plates C1 of the bicycle chain C and less than an outer chain space C21 defined between the pair of opposing outer link plates C2 of the bicycle chain C. The fourth chain engagement width W22 is less than the inner chain space C11. However, the fourth chain engagement width W22 may be equal to or greater than the third chain engagement width W21. The third chain engagement width W21 may be less than the inner chain space C11.

In the present embodiment, as shown in fig. 5 and 8, the total number of the plurality of sprocket teeth 32 is an even number, and the total number of the plurality of second sprocket teeth 44 is an even number. For example, the total number of the plurality of sprocket teeth 32 is thirty-six, and the total number of the plurality of second sprocket teeth 44 is twenty-four. However, the total number of the plurality of sprocket teeth 32 is not limited to the present embodiment. The total number of the plurality of second sprocket teeth 44 is not limited to the present embodiment.

As seen in fig. 5 and 8, the bicycle sprocket 12 has a first pitch diameter PCD1 defined by the plurality of sprocket teeth 32. The smaller sprocket 14 has a second pitch diameter PCD2 defined by the plurality of second sprocket teeth 44. The first pitch diameter PCD1 is larger than the second pitch diameter PCD 2.

The first pitch circle diameter PCD1 may be defined based on a center C31 of a pin C3 (fig. 25) of a bicycle chain C engaged with the plurality of first sprockets 32. The second pitch circle diameter PCD2 may be defined based on a center C31 of a pin C3 (fig. 25) of the bicycle chain C engaged with the plurality of second sprockets 44.

As seen in fig. 5, the bicycle sprocket 12 includes at least one shift facilitating area FA1 to facilitate at least one of a first shifting operation and a second shifting operation. In the first shifting operation, the bicycle chain C is shifted from the bicycle sprocket 12 toward the smaller sprocket 14 adjacent to the bicycle sprocket 12 in an axial direction D2 that is parallel to a rotational center axis a1 of the bicycle sprocket 12 without an additional sprocket between the bicycle sprocket 12 and the smaller sprocket 14. In the second shifting operation, the bicycle chain C is shifted from the smaller sprocket 14 toward the bicycle sprocket 12.

In the present embodiment, the at least one shift facilitation area FA1 includes a plurality of shift facilitation areas FA1 to facilitate at least one of the first and second shift operations. Specifically, the plurality of shift facilitation areas FA1 facilitate both the first and second shift operations. However, the total number of the shift facilitation areas FA1 is not limited to the present embodiment.

The shift promoting area FA1 is a circumferential area defined by elements configured to promote at least one of the first and second shift operations. In the present embodiment, the shift promoting area FA1 includes: a first shift facilitation area FA11 that facilitates the first shift operation and a second shift facilitation area FA12 that facilitates the second shift operation. The first shift promoting area FA11 overlaps the second shift promoting area FA12 in the circumferential direction D1 and is disposed on the upstream side of the second shift promoting area FA12 in the driving rotation direction D11. However, the positional relationship between the first and second shift promoting areas FA11 and FA12 is not limited to the present embodiment.

As seen in fig. 5, the bicycle sprocket 12 includes at least one drive promoting area FA 2. In the present embodiment, the at least one drive promoting area FA2 includes a plurality of drive promoting areas FA 2. The drive promoting regions FA2 are disposed outside the shift promoting regions FA1 and between the shift promoting regions FA1 in the circumferential direction D1. However, the total number of the drive promoting areas FA2 is not limited to the present embodiment. The drive promoting area FA2 is configured to promote the holding and driving of the bicycle chain C, rather than promoting the shifting operation. The shift facilitation performance of the drive facilitation area FA2 is lower than that of the shift facilitation area FA 1. In the present embodiment, neither the shift facilitating cut surface, the shift facilitating groove, nor the shift facilitating projection is provided in the drive facilitating area FA 2. Therefore, the possibility that derailing and receiving of the bicycle chain C is smoothly performed in the drive promoting area FA2 is less than in the shift promoting area FA 1. The drive promoting area FA2 is defined to include points that are 90 degrees offset from top dead center and bottom dead center of the bicycle crank assembly 10, respectively, in the circumferential direction D1. In other words, the drive promoting area FA2 does not include the top dead center and the bottom dead center of the bicycle crank assembly 10, while the shift promoting area FA1 includes the top dead center and the bottom dead center.

As seen in fig. 11, the plurality of sprocket teeth 32 includes a first derailleur tooth 54 that is disposed on the outer edge 30A of the sprocket body 30 to first disengage the bicycle chain C from the bicycle sprocket 12 in a first shifting operation. In the present embodiment, as seen in fig. 5, the plurality of sprocket teeth 32 includes a plurality of first derailleurs 54 that are respectively disposed in the shift promoting areas to first disengage the bicycle chain C from the bicycle sprocket 12 in the first shifting operation. However, the total number of the first derailing teeth 54 is not limited to the present embodiment.

As seen in fig. 11, the bicycle sprocket 12 includes at least one shift facilitating protrusion 56, the shift facilitating protrusion 56 being configured to engage the bicycle chain C in a first shifting operation in which the bicycle chain C is shifted from the bicycle sprocket 12 toward the smaller sprocket 14 adjacent to the bicycle sprocket 12 in an axial direction D2 that is parallel to a rotational center axis a1 of the bicycle sprocket 12 without an additional sprocket between the bicycle sprocket 12 and the smaller sprocket 14. .

In the present embodiment, as seen in fig. 5, the at least one shift facilitating protrusion 56 includes a plurality of shift facilitating protrusions 56 configured to engage the bicycle chain C in the first shifting operation. However, the total number of the shift facilitation protrusions 56 is not limited to the present embodiment. The shift promoting protrusions 56 may also be referred to as first shift promoting protrusions 56.

As shown in fig. 11, the shift facilitating protrusion 56 is provided in the shift facilitating area FA1 (the first shift facilitating area FA11) to facilitate the first shifting operation. The shift facilitation protrusion 56 is disposed on the upstream side of the first derailing tooth 54 in the driving rotation direction D11.

The at least one shift facilitating protrusion 56 is at least partially disposed closer to the central axis of rotation a1 than the at least one first tooth 34. One of the at least one first tooth 34 is at least partially disposed closest to the at least one shift facilitating protrusion 56 among the at least one first tooth 34. In the present embodiment, the plurality of sprocket teeth 32 includes a first adjacent tooth 58, the first adjacent tooth 58 being closest to the shift facilitating protrusion 56 in the plurality of sprocket teeth 32. In the present embodiment, the at least one first tooth 34 includes a first adjacent tooth 58. The first derailing tooth 54 is adjacent to the first adjacent tooth 58 in the drive rotation direction D11 with no additional teeth between the first derailing tooth 54 and the first adjacent tooth 58. The first adjacent tooth 58 is provided to the upstream side of the first derailing tooth 54. However, the positional relationship among the first derailing tooth 54, the shift facilitation protrusion 56, and the first adjacent tooth 58 is not limited to this embodiment.

As seen in fig. 12 and 13, the shift facilitating protrusion 56 protrudes from the first axial surface 38 in the axial direction D2 to contact the bicycle chain C (e.g., the outer link plate C2) in the second shifting operation. The shift facilitating protrusion 56 is coupled to the sprocket body 30 to contact a bicycle chain C (e.g., the outer link plate C2) in a first shifting operation. The shift facilitation projection 56 is a separate component from the sprocket body 30 and is fixed to the sprocket body 30. However, the shift facilitation protrusion 56 can be integrally provided with the sprocket body 30 as a one-piece, unitary member.

In the present embodiment, as shown in fig. 14, the shift facilitation protrusion 56 includes a contact portion 56A, a fixed portion 56B, and an intermediate portion 56C. The contact portion 56A is provided on the first axial surface 38 to contact the outer link plate C2. The contact portion 56A is provided at one end of the intermediate portion 56C. The fixed portion 56B is disposed on the first reverse axial surface 40. The fixed portion 56B is provided at the other end of the intermediate portion 56C. The intermediate portion 56C extends through the bore 30B of the sprocket body 30. The contact portion 56A has an outer diameter greater than that of the intermediate portion 56C. The fixed portion 56B has an outer diameter greater than that of the intermediate portion 56C. The contact portion 56A, the fixing portion 56B, and the intermediate portion 56C form a caulking portion. However, the structure of the shift facilitation protrusion 56 is not limited to this embodiment.

As seen in fig. 12 and 13, the contact portion 56A has a curved surface 56A1 that contacts the outer link plate C2 in the first shift operation. Specifically, the contact portion 56A has a cylindrical shape. The curved surface 56A1 is defined around the contact portion 56A and has a circumferential circular shape. However, the shape of the contact portion 56A is not limited to the present embodiment.

As seen in fig. 11, the bicycle sprocket 12 includes at least one raised portion 60, the at least one raised portion 60 being disposed on a downstream side of the at least one shift facilitating protrusion 56 in a driving rotation direction D11, the bicycle sprocket 12 rotating in a driving rotation direction D11 during pedaling. In the present embodiment, as shown in fig. 5, the at least one projecting portion 60 includes a plurality of projecting portions 60 that are respectively provided on the downstream sides of the plurality of shift facilitating projections 56 in the driving rotation direction D11. However, the total number of the convex portions 60 is not limited to the present embodiment.

As seen in fig. 11, the at least one raised portion 60 is configured to limit engagement of the at least one shift facilitating protrusion 56 with the bicycle chain C during at least one of a second shifting operation and a first shifting operation of the bicycle chain C from the smaller sprocket 14 toward the bicycle sprocket 12. In the present embodiment, the boss portion 60 is configured to limit engagement of the shift facilitating protrusion 56 with the bicycle chain C in the second shifting operation. However, the raised portion 60 can be configured to limit the engagement of the shift facilitating protrusion 56 with the bicycle chain C in the first shifting operation.

The at least one raised portion 60 is at least partially disposed radially inward of the at least one shift facilitating protrusion 56 relative to the central axis of rotation a 1. In the present embodiment, the convex portion 60 is partially disposed radially inward of the shift facilitation protrusion 56 with respect to the rotational center axis a 1. The boss portion 60 is partially disposed closer to the rotational center axis a1 than the shift facilitation protrusion 56 is, as viewed in a direction parallel to the rotational center axis a 1. However, the positional relationship is not limited to the present embodiment.

The at least one raised portion 60 is at least partially disposed closer to the central axis of rotation a1 than the at least one second tooth 36. One of the at least one second tooth 36 is at least partially disposed closest to the at least one raised portion 60 among the at least one second tooth 36. In the present embodiment, the at least one raised portion 60 is at least partially disposed closer to the central axis of rotation a1 than the first derailing tooth 54. The first derailing tooth 54 is at least partially disposed closest to the at least one raised portion 60 in the plurality of sprocket teeth 32. Specifically, the convex portion 60 is integrally disposed closer to the rotational center axis a1 than the first derailing tooth 54. The first derailing tooth 54 is closest to the raised portion 60 among the plurality of sprocket teeth 32. However, the arrangement of the convex portion 60 is not limited to the present embodiment.

As shown in fig. 14, the plurality of sprocket teeth 32 includes a reference tooth 62 having a reference tooth center plane CP3, the reference tooth center plane CP3 being defined as bisecting a maximum axial width W11 of the reference tooth 62 in the axial direction D2. In the present embodiment, the reference tooth 62 is the first adjacent tooth 58. The reference tooth center plane CP3 coincides with the first center plane CP11 of the first adjacent tooth 58.

The at least one shift facilitating protrusion 56 has a first axial height H1 defined in the axial direction D2 from the reference tooth center plane CP 3. The at least one raised portion 60 has a second axial height H2 defined in the axial direction D2 from the reference tooth center plane CP 3. The second axial height H2 is greater than the first axial height H1. However, the second axial height H2 may be equal to or less than the first axial height H1.

As seen in FIG. 15, the at least one raised portion 60 is spaced from the at least one shift facilitating protrusion 56 by a distance DS1, the distance DS1 being equal to or less than two chain pitches. The at least one raised portion 60 is spaced from the at least one shift facilitating protrusion 56 by a distance DS1, the distance DS1 being equal to or less than one chain pitch. In the present embodiment, the raised portion 60 is spaced from the shift facilitating protrusion 56 by a distance DS1, with distance DS1 being equal to one chain pitch. The chain pitch is the linear distance defined between adjacent pins of the bicycle chain C.

As seen in fig. 16, the at least one raised portion 60 has a contact surface 60A, the contact surface 60A being configured to move the bicycle chain C toward the smaller sprocket 14. The contact surface 60A is configured to guide the bicycle chain C toward the smaller sprocket 14. The contact surface 60A is configured to move the bicycle chain C in the axial direction D2 away from the sprocket body 30. The contact surface 60A is planar and inclined with respect to the first reference center plane CP 10. The contact surface 60A has a radially outer end 60A1 and a radially inner end 60A 2. An axial distance AD1 is defined in the axial direction D2 between the contact surface 60A and the reference tooth center plane CP 3. The contact surface 60A is inclined to increase the axial distance AD1 from the radially outer end 60A1 to the radially inner end 60A 2.

As shown in fig. 15, the radially outer end portion 60a1 is disposed at least partially on the downstream side of the radially inner end portion 60a2 in the driving rotation direction D11. In the present embodiment, the radially outer end portion 60a1 is provided partially on the downstream side of the radially inner end portion 60a2 in the driving rotation direction D11. However, the positional relationship between the radially outer end portion 60a1 and the radially inner end portion 60a2 is not limited to the present embodiment. The radially outer end 60A1 has a first width W31. The radially inner end portion 60a2 has a second width W32 that is less than the first width W31. However, the second width W32 may be equal to or greater than the first width W31.

As shown in FIG. 16, an angle AG1 defined between the contact surface 60A and a reference tooth center plane CP3 of the reference tooth 62 is equal to or less than 50 degrees. The angle AG1 defined between the contact surface 60A and the reference tooth center plane CP3 of the reference tooth 62 is preferably equal to or less than 45 degrees. However, the angle is not limited to the present embodiment. Angle AG1 may be equal to or less than about 50 degrees. Angle AG1 may be equal to or less than about 45 degrees. Angle AG1 may be greater than 50 degrees.

The raised portion 60 is coupled to the sprocket body 30 to contact a bicycle chain C (e.g., the outer link plate C2) in the second shifting operation. The raised portion 60 is a separate member from the sprocket body 30 and is fixed to the sprocket body 30. However, the raised portion 60 can be provided integrally with the sprocket body 30 as a one-piece, unitary member.

In the present embodiment, the convex portion 60 includes a contact portion 60B, a fixing portion 60C, and an intermediate portion 60D. The contact portion 60B is provided on the first axial surface 38 to contact the outer link plate C2. The contact portion 60B is provided at one end of the intermediate portion 60D. The contact portion 60B includes a contact surface 60A. The fixed portion 60C is disposed on the first reverse axial surface 40. The fixed portion 60C is provided at the other end of the intermediate portion 60D. The intermediate portion 60D extends through the bore 30C of the sprocket body 30. The contact portion 60B has an outer diameter larger than that of the intermediate portion 60D. The fixation portion 60C has an outer diameter greater than that of the intermediate portion 60D. The contact portion 60B, the fixing portion 60C, and the intermediate portion 60D form a caulking portion. As shown in fig. 12 and 13, the contact portion 60B has a shape different from that of the contact portion 56A. However, the structure of the convex portion 60 is not limited to the present embodiment.

As seen in fig. 11, the plurality of sprocket teeth 32 includes at least one receiving tooth 64 disposed in the shift facilitating area FA1 to first receive the bicycle chain C in the second shifting operation. The receiving tooth 64 first receives the pair of opposing outer link plates C2 of the bicycle chain C in the second shifting operation. The receiving tine 64 is disposed on the downstream side of the first derailing tine 54 in the driving rotation direction D11 with no additional tine between the receiving tine 64 and the first derailing tine 54. In the present embodiment, as seen in fig. 5, the at least one receiving tooth 64 includes a plurality of receiving teeth 64 that are respectively disposed in the shift facilitating area FA1 to first receive the bicycle chain C in the second shifting operation. However, the total number of receiving teeth 64 is not limited to the present embodiment.

As shown in fig. 12 and 13, the first derailing tooth 54 includes a first derailing downstream cut surface 54A disposed on the first axial surface 38. The first derailing downstream cut surface 54A is provided on the downstream side in the driving rotation direction D11 in the first derailing tooth 54. The first derailing downstream cut surface 54A reduces interference between the first derailing tooth 54 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 54 first disengages the bicycle chain C from the bicycle sprocket 12 in the first shifting operation.

The first derailing tooth 54 includes a first derailing upstream chamfer 54B disposed on the first axial surface 38. The first derailing upstream chamfer 54B is provided on the upstream side in the driving rotation direction D11 in the first derailing tooth 54. The first derailing upstream chamfer 54B reduces interference between the first derailing tooth 54 and the bicycle chain C (e.g., the outer link plate C2) when the first derailing tooth 54 first disengages the bicycle chain C from the bicycle sprocket 12 in the first shifting operation.

as shown in fig. 17, the first derailing tooth 54 includes a first receiving downstream chamfer 54C disposed on the first reverse axial surface 40. The first receiving downstream chamfer 54C is disposed on the downstream side in the driving rotation direction D11 in the first derailing tooth 54. The first receiving downstream chamfer 54C reduces interference between the first derailing tooth 54 and the bicycle chain C (e.g., the inner link plate C1) when the receiving tooth 64 first receives the bicycle chain C in the second shifting operation. That is, the first derailing tooth 54 facilitates receipt of the bicycle chain C at the receiving tooth 64 in the second shifting operation.

The first derailing tooth 54 includes an additional upstream chamfer 54D disposed on the first reverse axial surface 40. An additional upstream chamfer 54D is provided on the upstream side in the driving rotation direction D11 in the first derailing tooth 54.

As shown in fig. 17, the receiving tooth 64 includes a second derailing upstream chamfer 64A disposed on the first reverse axial surface 40. The second derailing upstream cut surface 64A is provided on the upstream side in the receiving tooth 64 in the driving rotation direction D11. The second derailing upstream chamfer 64A reduces interference between the receiving tooth 64 and the bicycle chain C (e.g., the outer link plate C2) when the first derailing tooth 54 first disengages the bicycle chain C from the bicycle sprocket 12 in the first shifting operation.

The receiving tooth 64 includes a second receiving downstream cut surface 64B disposed on the first opposing axial surface 40. The second receiving downstream cut surface 64B is provided on the downstream side in the driving rotation direction D11 in the receiving tooth 64. The second receiving downstream chamfer 64B reduces interference between the receiving tooth 64 and the bicycle chain C (e.g., the outer link plate C2) when the receiving tooth 64 first receives the bicycle chain C in the second shifting operation.

As shown in fig. 12 and 13, the receiving tooth 64 includes an additional downstream cut surface 64C disposed on the first axial surface 38. An additional downstream cut face 64C is provided on the downstream side in the receiving tooth 64 in the driving rotation direction D11.

Receiving tooth 64 includes an additional upstream chamfer 64D disposed on first axial surface 38. An additional upstream chamfer 64D is provided on the upstream side in the receiving tooth 64 in the driving rotation direction D11.

As seen in fig. 11, the bicycle sprocket 12 includes at least one second shift facilitating protrusion 66, the at least one second shift facilitating protrusion 66 being configured to engage the bicycle chain C in a second shifting operation. In the present embodiment, as seen in fig. 5, the at least one second shift facilitating protrusion 66 includes a plurality of second shift facilitating protrusions 66, the plurality of second shift facilitating protrusions 66 being configured to engage the bicycle chain C in the second shifting operation. However, the total number of the second shift facilitation protrusions 66 is not limited to the present embodiment.

As shown in fig. 11, the second shift facilitating protrusion 66 is provided in the shift facilitating area FA1 (the second shift facilitating area FA12) to facilitate the second shifting operation. The second shift facilitating projection 66 is disposed on a downstream side of the receiving tooth 64 in the driving rotation direction D11.

The at least one second shift facilitating protrusion 66 is at least partially disposed closer to the rotational center axis a1 than the at least one first tooth 34. One of the at least one first tooth 34 is at least partially disposed closest to the at least one second shift facilitating protrusion 66 among the at least one first tooth 34. In the present embodiment, the at least one first tooth 34 includes a second adjacent tooth 68, the second adjacent tooth 68 being closest to the second shift facilitating protrusion 66 among the plurality of sprocket teeth 32. In the present embodiment, the at least one first tooth 34 includes a second adjacent tooth 68. The first derailing tooth 54 is adjacent to the second adjacent tooth 68 in the drive rotational direction D11 with no additional teeth between the first derailing tooth 54 and the second adjacent tooth 68. However, the positional relationship among the first derailing tooth 54, the second shift facilitation protrusion 66, and the second adjacent tooth 68 is not limited to the present embodiment.

As seen in fig. 12 and 13, the second shift facilitating protrusion 66 protrudes from the first axial surface 38 in the axial direction D2 to contact the bicycle chain C (e.g., the outer link plate C2) in the second shifting operation. The second shift facilitating projection 66 is coupled to the sprocket body 30 to contact the bicycle chain C (e.g., the outer link plate C2) in the first shifting operation. The second shift facilitation projection 66 is a separate member from the sprocket body 30 and is fixed to the sprocket body 30. However, the second shift facilitation protrusion 66 can be integrally provided with the sprocket body 30 as a one-piece, unitary member.

In the present embodiment, as shown in fig. 18, the second shift facilitation protrusion 66 includes a contact portion 66A, a fixed portion 66B, and an intermediate portion 66C. The contact portion 66A is provided on the first axial surface 38 to contact the outer link plate C2. The contact portion 66A is provided at one end of the intermediate portion 66C. The fixed portion 66B is disposed on the first reverse axial surface 40. The fixed portion 66B is provided at the other end of the intermediate portion 66C. The intermediate portion 66C extends through the bore 30D of the sprocket body 30. The contact portion 66A has an outer diameter greater than that of the intermediate portion 66C. The fixed portion 66B has an outer diameter greater than that of the intermediate portion 66C. The contact portion 66A, the fixing portion 66B, and the intermediate portion 66C form a caulking portion. However, the structure of the second shift facilitation protrusion 66 is not limited to the present embodiment.

As seen in fig. 16, the at least one second shift facilitating protrusion 66 has a third axial height H3 defined in the axial direction D2 from the reference tooth center plane CP 3. The third axial height H3 is greater than the second axial height H2. That is, the third axial height H3 is greater than the first axial height H1 (fig. 14). However, third axial height H3 may be equal to or less than first axial height H1 and second axial height H2.

As seen in fig. 11, the bicycle sprocket 12 includes at least one third shift facilitating protrusion 70, the at least one third shift facilitating protrusion 70 being configured to engage the bicycle chain C in a second shifting operation. In the present embodiment, as seen in fig. 5, the at least one third shift facilitating protrusion 70 includes a plurality of third shift facilitating protrusions 70, the plurality of third shift facilitating protrusions 70 being configured to engage the bicycle chain C in the second shifting operation. However, the total number of the third shift facilitation protrusions 70 is not limited to the present embodiment.

As shown in fig. 11, the third shift facilitating protrusion 70 is provided in the shift facilitating area FA1 (the second shift facilitating area FA12) to facilitate the second shifting operation. The third shift facilitating protrusion 70 is disposed on the downstream side of the receiving tooth 64 in the driving rotation direction D11. The third shift facilitation protrusion 70 is disposed on an upstream side of the second shift facilitation protrusion 66 in the driving rotation direction D11.

The at least one third shift facilitating protrusion 70 is at least partially disposed closer to the rotational center axis a1 than the at least one second tooth 36. One of the at least one first tooth 34 is at least partially disposed closest to the at least one third shift facilitating protrusion 70 among the at least one first tooth 34. In the present embodiment, the at least one second tooth 36 includes a third adjacent tooth 72, the third adjacent tooth 72 being closest to the third shift facilitating protrusion 70 among the plurality of sprocket teeth 32. In the present embodiment, the at least one second tooth 36 includes a third adjacent tooth 72. Receiving tooth 64 is adjacent to the third adjacent tooth 72 in the drive rotational direction D11 with no additional teeth between receiving tooth 64 and the third adjacent tooth 72. The third adjacent tooth 72 is disposed between the receiving tooth 64 and the second adjacent tooth 68 in the circumferential direction D1. However, the positional relationship among the receiving teeth 64, the second and third shift facilitating protrusions 66, 70, and the third adjacent teeth 72 is not limited to the present embodiment.

As shown in fig. 17, the third adjacent tooth 72 includes a third derailed upstream chamfer 72A disposed on the first reverse axial surface 40. The third derailing upstream chamfer 72A is provided on the upstream side in the driving rotation direction D11 in the third adjacent tooth 72. The third derailing upstream chamfer 72A reduces interference between the third adjacent tooth 72 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 54 first disengages the bicycle chain C from the bicycle sprocket 12 in the first shifting operation.

As shown in fig. 12 and 13, the third adjacent tooth 72 includes a third receiving upstream chamfer 72B disposed on the first axial surface 38. The third receiving upstream chamfer 72B is disposed on the downstream side in the driving rotation direction D11 in the third adjacent tooth 72. The third receiving upstream chamfer 72B reduces interference between the third adjacent tooth 72 and the bicycle chain C (e.g., the inner link plate C1) when the receiving tooth 64 first receives the bicycle chain C in the second shifting operation.

The third adjacent tooth 72 includes an additional downstream chamfer 72C disposed on the first axial surface 38. An additional downstream chamfer 72C is provided on the downstream side of the receiving tooth 64 in the driving rotation direction D11.

As shown in fig. 17, the third adjacent tooth 72 includes an additional downstream chamfer 72D disposed on the first reverse axial surface 40. An additional downstream chamfer 72D is provided on the downstream side of the receiving tooth 64 in the driving rotation direction D11.

As seen in fig. 12 and 13, the third shift facilitating protrusion 70 protrudes from the first axial surface 38 in the axial direction D2 to contact the bicycle chain C (e.g., the outer link plate C2) in the second shifting operation. The third shift facilitating projection 70 is coupled to the sprocket body 30 to contact the bicycle chain C (e.g., the outer link plate C2) in the first shifting operation. The third shift facilitation protrusion 70 is a separate member from the sprocket body 30 and is fixed to the sprocket body 30. However, the third shift facilitation protrusion 70 can be integrally provided with the sprocket body 30 as a one-piece, unitary member.

In the present embodiment, the third shift facilitating projection 70 is coupled to the sprocket body 30 to contact the inner link plate C1 of the bicycle chain C in the second shifting operation. The third shift facilitating projection 70 is coupled to the sprocket body 30 to contact an intermediate portion of an inner link plate C1 of the bicycle chain C in the second shifting operation. In the second shifting operation, the third shift facilitation protrusion 70 is partially inserted into the inner link space C11 of the opposing pair of inner link plates C1.

As seen in fig. 19, the at least one third shift facilitating protrusion 70 has a fourth axial height H4 defined in the axial direction D2 from the reference tooth center plane CP 3. Fourth axial height H4 is less than third axial height H3. As shown in FIG. 16, fourth axial height H4 is less than second axial height H2. As shown in fig. 14, the fourth axial height H4 is greater than the first axial height H1. However, the fourth axial height H4 may be equal to or less than the first axial height H1. Fourth axial height H4 may be equal to or greater than second axial height H2 and third axial height H3.

As seen in fig. 19 to 21, the third shift facilitation protrusion 70 includes a coupling body 70A and a protrusion 70B. The coupling body 70A is coupled to the sprocket body 30. The projection 70B extends radially outward from the coupling body 70A relative to the rotational center axis a 1. The projection 70B is spaced from the sprocket body 30 in an axial direction D2 that is parallel to the rotational center axis a 1. In the present embodiment, the projection 70B is spaced apart from the second tooth 36 (third adjacent tooth 72) in the axial direction D2. In the second shifting operation, the protrusion 70B can contact the bicycle chain C.

The coupling body 70A includes a base 70A1, a retainer 70A2, and an intermediate portion 70A3 (fig. 19). The base 70a1 is disposed on the first axial surface 38. The protrusion 70B extends radially outward from the base 70a1 with respect to the rotational center axis a 1. The base 70A1 is contactable with an inner link plate C1 of a bicycle chain C. The fixed portion 70a2 is disposed on the first reverse axial surface 40. The middle portion 70A3 connects the anchor portion 70A2 to the base 70A1 and extends through the aperture 30E of the sprocket body 30. The coupling body 70A has a first central axis a4 extending in the axial direction D2. Although the first center axis a4 of the coupling body 70A is parallel to the axial direction D2 in the present embodiment, the first center axis a4 may not be parallel to the axial direction D2. The base 70a1 has an outer diameter that is greater than the outer diameter of the intermediate portion 70 A3. The fixation section 70a2 has an outer diameter that is greater than the outer diameter of the intermediate section 70 A3. The base 70a1, the securing portion 70a2, and the intermediate portion 70A3 form a clinch. However, the structure of the third shift facilitation protrusion 70 is not limited to the present embodiment.

As shown in fig. 19, the third shift facilitating protrusion 70 is arranged to maintain at least one of a gap between the protrusion 70B and the inner link plate C1 in the axial direction D2 and a gap between the third adjacent tooth 72 and the inner link plate C1 in the axial direction D2 during pedaling. The maximum axial distance L3 defined between the projection 70B and the third adjacent tooth 72 in the axial direction D2 is greater than the axial width W4 of the inner link plate C1.

The maximum axial distance L3 is in the range of 0.5mm to 4.0 mm. The maximum axial distance L3 is preferably equal to or greater than 1.0 mm. The maximum axial distance L3 is preferably equal to or less than 3.8 mm. The maximum axial distance L3 is preferably in the range of 1.0mm to 2.0 mm. However, the maximum axial distance L3 may be in a range different from the above range.

As shown in fig. 19 to 21, the projection 70B includes a radially inner portion 70C, a radially outer end portion 70D, and an inclined surface 70E. The radially inner portion 70C is coupled to the coupling body 70A. The radially outer end portion 70D is disposed radially outward of the radially inner portion 70C with respect to the rotational center axis a 1. The inclined surface 70E faces the sprocket body 30 in the axial direction D2. The inclined surface 70E is inclined to gradually approach the sprocket body 30 in the axial direction D2 from the radially outer end 70D toward the radially inner portion 70C. When the third shift facilitating protrusion 70 is engaged with the bicycle chain C, the inclined surface 70E guides the inner link plate C1 of the bicycle chain C toward the third adjacent tooth 72 along the axial direction D2.

As shown in fig. 11, the projection 70B is disposed to at least partially overlap one of the plurality of sprocket teeth 32 when viewed in the axial direction D2 that is parallel to the rotational center axis a 1. In the present embodiment, the protrusion 70B is provided to partially overlap with the third adjacent tooth 72 when viewed in the axial direction D2 parallel to the rotation center axis a 1.

as seen in fig. 19, the third shift facilitating projection 70 is engaged between the pair of opposed link plates of the bicycle chain C when the bicycle chain C is shifted from the smaller sprocket 14 to the bicycle sprocket 12. In the present embodiment, the third shift facilitating projection 70 is engaged between the pair of opposing inner link plates C1 of the bicycle chain C when the bicycle chain C is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

As seen in fig. 22, the third shift facilitating protrusion 70 is arranged not to be inserted between the pair of opposing link plates of the bicycle chain C in the first shifting operation. In the present embodiment, the third shift facilitating protrusion 70 is arranged not to be inserted between the pair of opposing inner link plates C1 of the bicycle chain C in the first shifting operation.

As seen in fig. 11, the sprocket body 30 includes a shift facilitating recess 74 disposed in the shift facilitating area FA1 to facilitate the second shifting operation. Specifically, the shift facilitating recess 74 is disposed on the first axial surface 38 to reduce interference between the sprocket body 30 and the bicycle chain C in the second shifting operation.

In the present embodiment, the shift promoting area FA1 is defined from the upstream tooth bottom portion 58T of the first adjacent tooth 58 to the downstream circumferential end portion 74A of the shift promoting recess 74 in the circumferential direction D1. The first shift promoting area FA11 is defined from the upstream tooth bottom 58T of the first adjacent tooth 58 to the downstream tooth bottom 72T of the third adjacent tooth 72 in the circumferential direction D1. The second shift promoting area FA12 is defined from the upstream tooth bottom portion 54T of the first derailing tooth 54 to the downstream circumferential end portion 74A of the shift promoting recess 74 in the circumferential direction D1. However, the first and second shift facilitation areas FA11 and FA12 are not limited to the present embodiment.

The first and second shift operations will be described in detail below with reference to fig. 23 to 30.

As seen in fig. 23, in the first shifting operation, the bicycle chain C is shifted from the bicycle sprocket 12 toward the smaller sprocket 14 by the front derailleur (not shown). The third derailing upstream chamfer 72A promotes the inclination of the inner link plate C1A toward the smaller sprocket 14 with respect to the axial direction D2. The second derailing upstream chamfer 64A promotes the outer link plate C2A to lean toward the smaller sprocket 14 relative to the axial direction D2. Further, the first derailing downstream cut surface 54A guides the inner link plate C1B toward the smaller sprocket 14 in the axial direction D2. Thus, in the first shifting operation, the bicycle chain C is first disengaged from the bicycle sprocket 12 at the first derailleurs 54.

In the first shifting operation, as seen in FIG. 25, the inner link plate C1B is not guided by the contact surface 60A of the raised portion 60 toward the smaller sprocket 14 because the inner link plate C1E is adjacent to or in contact with the first derailleurs teeth 54. This brings the outer link plate C2B into contact with the shift facilitating protrusion 56. Thus, as shown in fig. 24, the outer link plate C2B is supported by the shift facilitating projection 56. In this state, the bicycle chain C extends from the shift facilitating protrusion 56 on the path RT1 as viewed in the axial direction D2. The path RT1 is different from the path RT2 of the bicycle chain C as viewed in the axial direction D2 without the bicycle sprocket 12 including the shift facilitating protrusion 56. Specifically, path RT1 is longer than path RT 2. This makes it easy for the bicycle chain C to engage with the second sprocket tooth 44 of the smaller sprocket 14 in the first shifting operation. Thus, the shift promoting area FA1 promotes the first shift operation.

As seen in fig. 26, in the second shifting operation, the bicycle chain C is shifted from the smaller sprocket 14 toward the bicycle sprocket 12 by the front derailleur (not shown). As seen in fig. 26 to 28, when the bicycle chain C is not engaged with the second and third shift facilitating protrusions 66 and 70, the outer link plate C2C of the bicycle chain C is in contact with the raised portion 60. As seen in fig. 28, the outer link plate C2C of the bicycle chain C is moved in the axial direction D2 away from the shift facilitating protrusion 56 by the contact surface 60A of the raised portion 60. This prevents the bicycle chain C from contacting the shift facilitating protrusion 56, as seen in fig. 29. In other words, this prevents the bicycle chain C from undesirably engaging the bicycle sprocket 12 or falling off the bicycle sprocket 12 by contacting the shift facilitating protrusion 56. Thus, as seen in fig. 30, in the second shifting operation, the bicycle chain C can be positively engaged with the second and third shift facilitating protrusions 66 and 70 without being lifted by the shift facilitating protrusion 56.

As seen in fig. 18 and 30, in a state where the bicycle chain C is shifted through the front derailleur toward the bicycle sprocket 12, the outer link plate C2D of the bicycle chain C is in contact with the second shift facilitating projection 66. In a state where the second shift facilitating protrusion 66 is in contact with the outer link plate C2D of the bicycle chain C, the outer link plate C2D of the bicycle chain C is moved upward by the second shift facilitating protrusion 66 in response to the rotation of the bicycle sprocket 12. At this time, as seen in fig. 19, the inner link plate C1D is guided by the inclined surface 70E of the third shift facilitating projection 70 in the axial direction D2 toward the third adjacent tooth 72. Thus, the inner link plate C1D is moved in the axial direction D2 toward the third adjacent tooth 72 by the third shift facilitating protrusion 70, causing the third shift facilitating protrusion 70 to be inserted into the inner chain space C11D of the opposing pair of inner link plates C1D and C1E.

In this state, as seen in FIG. 31, the third receiving upstream chamfer 72B promotes the inclination of the inner link plate C1D of the bicycle chain C relative to the axial direction D2. Thus, as the bicycle sprocket 12 further rotates in the drive rotation direction D11 about the rotational center axis a1, the opposing pair of outer link plates C2E and C2F are first received by the receiving teeth 64 in the second shifting operation.

When the bicycle sprocket 12 is further rotated in the driving rotation direction D11 about the rotational center axis A1, the third shift facilitating projection 70 immediately disengages from the inner link plates C1D and C1E. Thereafter, as shown in fig. 22, the third adjacent tooth 72 is inserted into the inner chain space C11D of the opposite pair of inner link plates C1D and C1E. This causes the opposing inner link plates C1A and C1B to engage the third adjacent tooth 72.

Second embodiment

Hereinafter, a bicycle crank assembly 210 including a bicycle sprocket 212 according to a second embodiment will be explained with reference to fig. 32 to 47. The bicycle sprocket 212 has the same structure as the bicycle sprocket 12, except for the plurality of sprocket teeth 32. Accordingly, elements having substantially the same function as elements of the first embodiment are numbered the same and will not be described in detail herein for the sake of brevity.

As seen in fig. 32 and 33, the bicycle crank assembly 210 includes a bicycle sprocket 212 and the smaller sprocket 14. The bicycle sprocket 212 includes a sprocket body 30, a plurality of sprocket teeth 232, a shift facilitating protrusion 56, a raised portion 60 and a second shift facilitating protrusion 66. The bicycle sprocket 212 does not include the third shift facilitating protrusion 70.

As shown in fig. 34, the plurality of sprocket teeth 232 have substantially the same structure as the plurality of sprocket teeth 32 of the first embodiment. In the present embodiment, the plurality of sprocket teeth 232 includes at least one first tooth 234 and at least one second tooth 236. The at least one first tooth 234 includes a plurality of first teeth 234. The at least one second tooth 236 includes a plurality of second teeth 236.

As shown in fig. 35, the at least one first tooth 234 has a first chain engagement width W211 defined along the axial direction D2. In this embodiment, first tooth 234 includes a first chain engagement surface 234A and a first additional chain engagement surface 234B. The first link engaging surface 234A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., an outer link plate C2). The first additional chain engagement surface 234B faces the axial direction D2 and is disposed on an opposite side of the first chain engagement surface 234A along the axial direction D2. The first additional link engaging surface 234B is contactable with a bicycle chain C (e.g., the outer link plate C2). A first chain engagement width W211 is defined between the first chain engagement surface 234A and the first additional chain engagement surface 234B in the axial direction D2.

The first tooth 234 has a first center plane CP211, the first center plane CP211 being defined to bisect the first chain engagement width W211 along the axial direction D2. The first center plane CP211 is perpendicular to the rotation center axis a 1. The first center plane CP211 is offset from the first reference center plane CP10 in the axial direction D2. However, the first center plane CP211 may coincide with the first reference center plane CP10 in the axial direction D2. The first teeth 234 have an asymmetrical shape with respect to the first center plane CP211 along the axial direction D2. However, the first teeth 234 may have a symmetrical shape with respect to the first center plane CP211 along the axial direction D2.

As shown in fig. 36, the at least one second tooth 236 has a second chain engagement width W212 defined along the axial direction D2. In this embodiment, the second tooth 236 includes a second chain engagement surface 236A and a second additional chain engagement surface 236B. The second chain engagement surface 236A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., an inner link plate C1). The second additional chain engagement surface 236B faces the axial direction D2 and is disposed on an opposite side of the second chain engagement surface 236A along the axial direction D2. The second additional link engaging surface 236B is contactable with a bicycle chain C (e.g., an inner link plate C1). The second chain engagement width W212 is defined between the second chain engagement surface 236A and the second additional chain engagement surface 236B along the axial direction D2.

The second tooth 236 has a second center plane CP212, the second center plane CP212 defined to bisect the second chain engagement width W212 along the axial direction D2. The second central plane CP212 is perpendicular to the rotational central axis a 1. The second center plane CP212 is offset from the first reference center plane CP10 in the axial direction D2. However, the second center plane CP212 may coincide with the first reference center plane CP10 in the axial direction D2. The second center plane CP212 coincides with the first center plane CP 211. However, the second center plane CP212 may be offset from the first center plane CP211 in the axial direction D2. The second tooth 236 has an asymmetrical shape with respect to the second center plane CP212 in the axial direction D2. However, the second tooth 236 may have a symmetrical shape with respect to the second center plane CP212 in the axial direction D2.

In the present embodiment, as shown in fig. 35 and 36, the second chain engagement width W212 is equal to the first chain engagement width W211. The first and second chain engagement widths W211, W212 are less than the inner chain space C11 and the outer chain space C21.

As seen in fig. 34, the bicycle sprocket 212 includes a first shift facilitation area FA21 to facilitate a first shift operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in a first chain phase state CS1 (fig. 37) in which the chain phase reference teeth 245 of the plurality of sprocket teeth 232 are received in the inner chain space C11. The bicycle sprocket 212 includes a third shift facilitation area FA23 to facilitate a third shift operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in a third chain phase state CS3 (fig. 38) in which the chain phase reference teeth 245 of the plurality of sprocket teeth 232 are received in the outer chain space C21. The position of the chain phase reference tooth 245 is not limited to this embodiment. The other teeth of the sprocket teeth 232 may be defined as chain phase reference teeth 245.

in the present embodiment, the bicycle sprocket 212 includes a pair of first shift facilitating areas FA21 to facilitate a first shifting operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in the first chain phase state CS1 (fig. 37). The bicycle sprocket 212 includes a pair of third shift facilitating areas FA23 to facilitate a third shifting operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in the third chain phase state CS3 (fig. 38). However, the total number of the first shift facilitation areas FA21 is not limited to the present embodiment. The total number of the third shift facilitation areas FA23 is not limited to the present embodiment.

As seen in FIG. 39, the smaller sprocket 14 has a second chain phase state CS2 defined by the circumferential positional relationship between the at least one third tooth 46, the pair of outer link plates C2 and the pair of inner link plates C1. In the second chain phase state CS2, the third tooth 46 is received in the outer chain space C21 and the fourth tooth 48 is received in the inner chain space C11. As seen in fig. 37, the smaller sprocket 14 includes a second shift facilitating area FA22 to facilitate a second shifting operation of the bicycle chain C from the smaller sprocket 14 to the bicycle sprocket 212.

As seen in fig. 34, the first shift facilitation area FA21 at least partially overlaps the third shift facilitation area FA23 in the circumferential direction D1 defined about the central axis of rotation a 1. In the present embodiment, the first shift promoting area FA21 partially overlaps the third shift promoting area FA23 in the circumferential direction D1. The first shift promoting area FA21 is disposed on the upstream side of the third shift promoting area FA23 in the driving rotation direction D11. However, the positional relationship between the first and third shift facilitation areas FA21 and FA23 is not limited to the present embodiment. For example, the first shift promoting area FA21 may completely overlap the third shift promoting area FA23 in the circumferential direction D1. The first shift promoting area FA21 may be spaced from the third shift promoting area FA23 in the circumferential direction D1 without overlapping the third shift promoting area FA 23. The first shift promoting area FA21 may be disposed on the downstream side of the third shift promoting area FA23 in the driving rotation direction D11.

As seen in fig. 37, the plurality of sprocket teeth 232 includes a first derailleurs 248 disposed on the outer edge 30A of the sprocket body 30 to first disengage the bicycle chain C from the bicycle sprocket 212 in a first shifting operation. The plurality of sprocket teeth 232 further includes a second derailleur tooth 246 disposed on the outer edge 30A of the sprocket body 30 to first disengage the bicycle chain C from the bicycle sprocket 212 in a third shifting operation in which the bicycle chain C is shifted from the bicycle sprocket 212 toward the smaller sprocket 14. The third shift operation is different from the first shift operation in a chain phase of the bicycle chain C. The second derailing tooth 246 is adjacent to the first derailing tooth 248 in a circumferential direction D1 defined about the central axis of rotation a1, with no additional teeth between the second derailing tooth 246 and the first derailing tooth 248. However, additional teeth may be provided between the second derailing tooth 246 and the first derailing tooth 248 in the circumferential direction D1.

The second derailing tooth 246 is disposed on the downstream side of the first derailing tooth 248 in the driving rotation direction D11. The at least one raised portion 60 is at least partially disposed between the first derailing tooth 248 and the second derailing tooth 246 in a circumferential direction D1 defined about the central axis of rotation a 1. In the present embodiment, the at least one raised portion 60 is at least partially disposed closer to the first derailing tooth 248 than to the second derailing tooth 246 in a circumferential direction D1 defined about the central axis of rotation a 1. The second derailing tooth 246 is disposed on the downstream side of the first derailing tooth 248 in the driving rotation direction D11, with no other tooth between the first derailing tooth 248 and the second derailing tooth 246. However, the arrangement of the first derailing tooth 248 and the second derailing tooth 246 is not limited to the present embodiment.

As shown in fig. 40 and 41, the first derailing tooth 248 includes a first downstream chamfer 248A disposed on the first axial surface 38. The first downstream tangential plane 248A is disposed on a downstream side in the driving rotational direction D11 in the first derailing tooth 248, and the bicycle crank assembly 210 rotates about the central axis of rotation a1 in the driving rotational direction D11 during pedaling. The first downstream chamfer 248A reduces interference between the first derailing tooth 248 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 248 first disengages the bicycle chain C from the bicycle sprocket 212 in the first chain phase state CS 1. In other words, the first downstream cut surface 248A can guide the bicycle chain C to disengage from the first derailing tooth 248 toward the smaller sprocket 14.

The second derailing tooth 246 includes a second downstream cut 246A disposed on the first axial surface 38. The second downstream tangential face 246A is disposed on the downstream side in the driving rotation direction D11 in the second derailing tooth 246. The second downstream chamfer 246A reduces interference between the second derailing tooth 246 and the bicycle chain C (e.g., the inner link plate C1) when the second derailing tooth 246 first derails the bicycle chain C from the bicycle sprocket 212 in the second chain phase state CS 2. In other words, the second downstream cut surface 246A can guide the bicycle chain C to disengage from the second derailing tooth 246 toward the smaller sprocket 14.

the second derailing tooth 246 includes a second upstream tangent surface 246B disposed on the first axial surface 38. The second upstream tangential plane 246B is disposed on an upstream side in the driving rotational direction D11 in the second derailing tooth 246, and the bicycle crank assembly 210 rotates about the central rotational axis a1 in the driving rotational direction D11 during pedaling. The second upstream cut surface 246B promotes bending of the bicycle chain C toward the smaller sprocket 14 to smoothly guide the bicycle chain C toward the smaller sprocket 14 in the first shifting operation.

As shown in fig. 42, the second derailing tooth 246 includes a second reverse upstream chamfer 246C disposed on the first reverse axial surface 40. The second reverse upstream chamfer 246C is disposed on the upstream side in the driving rotation direction D11 in the second derailing tooth 246, and the bicycle crank assembly 210 rotates about the center axis of rotation a1 in the driving rotation direction D11 during pedaling. The second reverse upstream chamfer 246C reduces interference between the first derailing tooth 248 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 248 first disengages the bicycle chain C from the bicycle sprocket 212 in the first chain phase state CS 1. In other words, the second reverse upstream cut surface 246C urges the bicycle chain C toward the smaller sprocket 14 during the third shifting operation.

In this embodiment, the second derailing tooth 246 includes a second downstream cut face 246A, a second upstream cut face 246B, and a second reverse upstream cut face 246C. The first derailing tooth 248 includes a first downstream cut surface 248A. However, at least one of the second downstream cut face 246A, the second upstream cut face 246B, and the second reverse upstream cut face 246C may be omitted from the second derailing tooth 246. The first downstream chamfer 248A may be omitted from the first derailing tooth 248.

As shown in fig. 37, the plurality of sprocket teeth 232 include derailment-promoting teeth 250. The derailing facilitating tooth 250 is disposed in the first shift facilitating area FA21 to facilitate disengagement of the bicycle chain C from the bicycle sprocket 212 at the second derailing tooth 246 during the first shifting operation. A derailing facilitation tooth 250 is also provided in the third shift facilitation area FA23 to facilitate disengagement of the bicycle chain C from the bicycle sprocket 212 at the first derailing tooth 248 in the third shifting operation. The derailment-promoting tooth 250 is disposed on the downstream side of the second derailment tooth 246 in the driving rotation direction D11. The derailment-promoting tooth 250 is disposed on the downstream side of the first derailment tooth 248 in the driving rotation direction D11. The derailment-promoting tooth 250 is adjacent to the second derailment tooth 246 in the circumferential direction D1, with no additional teeth between the second derailment tooth 246 and the derailment-promoting tooth 250. However, additional teeth may be provided between the second derailment tooth 246 and the derailment facilitating tooth 250 in the circumferential direction D1.

The derailment-promoting tooth 250 includes a second reverse upstream chamfer 250A disposed on the first reverse axial surface 40. A second reverse upstream chamfer 250A is provided on the upstream side in the driving rotation direction D11 in the derailment-promoting tooth 250. The second reverse upstream chamfer 250A reduces interference between the second derailing tooth 246 and the bicycle chain C (e.g., the inner link plate C1) when the second derailing tooth 246 first disengages the bicycle chain C from the bicycle sprocket 212 in the first shifting operation. In other words, the second reverse upstream tangent surface 250A urges the bicycle chain C to move toward the smaller sprocket 14 during the first shifting operation. The second reverse upstream chamfer 250A also reduces interference between the first derailing tooth 248 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 248 first disengages the bicycle chain C from the bicycle sprocket 212 in the third shifting operation. In other words, the second reverse upstream tangent surface 250A urges the bicycle chain C toward the smaller sprocket 14 during the third shifting operation. However, the second reverse upstream cut 250A may be omitted from the derailment-promoting teeth 250.

as shown in fig. 38, the plurality of sprocket teeth 232 includes adjacent teeth 254, the adjacent teeth 254 being closest to the shift facilitating protrusion 56 in the plurality of sprocket teeth 232. The first derailing tooth 248 is adjacent to the adjacent tooth 254 in the drive rotation direction D11 with no additional teeth between the first derailing tooth 248 and the adjacent tooth 254. The first derailing tooth 248 is disposed on the downstream side of the adjacent tooth 254 in the driving rotation direction D11. However, the positional relationship between the shift facilitation protrusion 56 and the first derailing tooth 248 is not limited to this embodiment. In the case where the smaller sprocket 14 and the bicycle sprocket 212 each have a predetermined total number of teeth, the positional relationship between the first derailing tooth 248 and the adjacent tooth 254 is not limited to the present embodiment. In the case where the smaller sprocket 14 and the bicycle sprocket 212 each have a predetermined total number of teeth, the shift facilitating protrusion 56 can be omitted from the bicycle sprocket 212.

As shown in fig. 40 and 41, the plurality of sprocket teeth 232 includes an outer chain receiving tooth 260 and an inner chain receiving tooth 262. The outer chain receiving tooth 260 is disposed in the second shift facilitating area FA22 to first receive the outer link plate pair C2 of the bicycle chain C in a second shifting operation of the bicycle chain C from the smaller sprocket 14 to the bicycle sprocket 212. The inner chain receiving tooth 262 is disposed in the second shift facilitating area FA22 to first receive the pair of inner link plates C1 of the bicycle chain C in the second shifting operation. Further, the inner chain receiving tooth 262 is disposed in the first shift facilitating area FA21 to facilitate disengagement of the bicycle chain C from the bicycle sprocket 212 at the second derailleurs 246 during the first shifting operation.

The inner chain-receiving tooth 262 is adjacent the derailment-promoting tooth 250 in the circumferential direction D1 with no additional teeth between the derailment-promoting tooth 250 and the inner chain-receiving tooth 262. The outer chain-receiving tooth 260 is adjacent the inner chain-receiving tooth 262 in the circumferential direction D1 with no additional teeth between the outer chain-receiving tooth 260 and the inner chain-receiving tooth 262.

As shown in fig. 40 and 41, the inner chain receiving tooth 262 includes an inner chain upstream cut 262A disposed on the first axial surface 38. The inner chain upstream tangent plane 262A is disposed on the upstream side in the inner chain receiving tooth 262 in the driving rotation direction D11. The inner chain upstream chamfer 262A reduces interference between the inner chain receiving tooth 262 and the bicycle chain C (e.g., the inner chain plate C1) when the inner chain receiving tooth 262 first receives the inner chain plate pair C1 in the second shift operation.

The inner chain receiving tooth 262 includes an inner chain downstream cut face 262B disposed on the first reverse axial surface 40. The inner chain downstream cut face 262B is disposed on the downstream side in the inner chain receiving tooth 262 in the driving rotation direction D11. The inner chain downstream chamfer 262B reduces interference between the inner chain receiving tooth 262 and the bicycle chain C (e.g., the inner chain plate C1) when the inner chain receiving tooth 262 first receives the inner chain plate pair C1 in the second shift operation.

As shown in fig. 42, the inner chain receiving tooth 262 includes an inner chain reverse upstream chamfer 262C disposed on the first reverse axial surface 40. The inner chain reverse upstream tangent plane 262C is disposed on the upstream side in the inner chain receiving tooth 262 in the driving rotation direction D11. The inner chain reverse upstream chamfer 262C reduces interference between the second derailing tooth 246 and the bicycle chain C (e.g., the outer link plate C2) when the second derailing tooth 246 first disengages the bicycle chain C from the bicycle sprocket 212 in the second chain phase state CS 2. In other words, the inner chain reverse upstream tangent surface 262C urges the bicycle chain C toward the smaller sprocket 14 during the first shifting operation.

In this embodiment, inner strand receiving tooth 262 includes an inner strand upstream cut 262A, an inner strand downstream cut 262B, and an inner strand reverse upstream cut 262C. However, at least one of the inner strand upstream cut 262A, the inner strand downstream cut 262B and the inner strand reverse upstream cut 262C may be omitted from the inner strand receiving tooth 262.

The outer chain receiving tooth 260 includes an outer chain downstream chamfer 260A disposed on the first reverse axial surface 40. The outer chain downstream cut face 260A is disposed on the downstream side in the outer chain receiving tooth 260 in the driving rotation direction D11. The outer chain downstream chamfer 260A reduces interference between the outer chain receiving tooth 260 and the bicycle chain C (one of the outer link plates C2) when the outer chain receiving tooth 260 first receives the outer link plate pair C2 in the second shift operation. However, the outer chain downstream chamfer 260A may be omitted from the outer chain receiving tooth 260.

As shown in fig. 40 and 41, the plurality of sprocket teeth 232 include a receiving facilitating tooth 264. The reception facilitating tooth 264 is disposed in the second shift facilitating area FA22 to facilitate the reception of the bicycle chain C at the outer and inner chain receiving teeth 260 and 262 during the second shifting operation. The reception facilitating tooth 264 is adjacent to the outer chain receiving tooth 260 in the circumferential direction D1 with no other tooth between the outer chain receiving tooth 260 and the reception facilitating tooth 264.

The receiving facilitating tooth 264 includes an upstream facilitating cut 264A and a downstream facilitating cut 264B. The upstream facilitating cut 264A is disposed on an upstream side in the driving rotation direction D11 in the receiving facilitating tooth 264. The downstream facilitating cut surface 264B is disposed on the downstream side in the driving rotation direction D11 in the receiving facilitating tooth 264. The upstream facilitating cut 264A is provided on the first axial surface 38 to reduce interference between the outer chain receiving tooth 260 and the bicycle chain C (the outer link plate C2) in the second shifting operation. The downstream facilitating cut surface 264B is disposed on the first axial surface 38 to reduce interference between the receiving facilitating tooth 264 and the bicycle chain C (outer link plate C2) in the second shifting operation.

As seen in fig. 37, the bicycle sprocket 212 includes additional shift facilitating protrusions 266 that are disposed in the second shift facilitating area FA22 to facilitate the second shifting operation. The additional shift facilitating protrusion 266 is disposed on the downstream side of the outer chain receiving tooth 260, the inner chain receiving tooth 262 and the receiving facilitating tooth 264 in the driving rotational direction D11. The additional shift facilitating protrusion 266 protrudes from the first axial surface 38 of the sprocket body 30 in the axial direction D2 to contact the bicycle chain C (e.g., the outer link plate C2) in the second shifting operation.

The plurality of sprocket teeth 232 includes an additional adjacent tooth 268, the additional adjacent tooth 268 being closest to the additional shift facilitating protrusion 266 in the plurality of sprocket teeth 232. The reception facilitation tooth 264 is adjacent to the additional adjacent tooth 268 in the driving rotation direction D11 with no additional teeth between the reception facilitation tooth 264 and the additional adjacent tooth 268. However, the positional relationship between the additional shift facilitation protrusion 266 and the reception facilitation tooth 264 is not limited to this embodiment.

In the present embodiment, as shown in fig. 38, the first shift promoting area FA21 is defined from the downstream circumferential end 74A of the shift promoting recess 74 to the upstream tooth bottom portion 262T1 of the inner chain receiving tooth 262 in the circumferential direction D1. The second shift promoting area FA22 is defined from the upstream tooth bottom 262T1 of the inner chain receiving tooth 262 to the upstream tooth bottom 254T of the adjacent tooth 254 in the circumferential direction D1. The third shift promoting region FA23 is defined from the downstream tooth bottom 262T2 of the inner chain receiving tooth 262 to the upstream tooth bottom 246T of the second derailing tooth 246 in the circumferential direction D1. However, the first, third and second shift promoting areas FA21, FA23 and FA22 are not limited to the present embodiment.

The first, second, and third shift operations will be described in detail below with reference to fig. 43 to 47.

As seen in fig. 43, in the third shifting operation (first chain phase state CS1), the bicycle chain C is shifted from the bicycle sprocket 212 toward the smaller sprocket 14 by the front derailleur (not shown). The second reverse upstream chamfer 250A promotes the inclination of the inner link plate C1D toward the smaller sprocket 14 with respect to the axial direction D2. The second reverse upstream chamfer 246C promotes the canting of the outer link plate C2D toward the smaller sprocket 14 relative to the axial direction D2. Further, the first downstream chamfer 248A guides the inner link plate C1E in the axial direction D2 toward the smaller sprocket 14. Thus, in the third shifting operation, the bicycle chain C first disengages the bicycle sprocket 212 from the first derailleurs 248.

In the third shifting operation, the inner link plate C1E is not guided by the contact surface 60A of the raised portion 60 toward the smaller sprocket 14 because the inner link plate C1E is adjacent to or in contact with the first derailleurs 248. This brings the outer link plate C2E into contact with the shift facilitating protrusion 56. Thus, as shown in fig. 44, the outer link plate C2E is supported by the shift facilitating projection 56. The bicycle chain C extends from the shift facilitation protrusion 56 on a different route than the route of the bicycle chain C for the first shifting operation when viewed in the axial direction D2. This easily engages the bicycle chain C with the first tooth 234 when the bicycle chain C is in the first chain phase state CS 1. Thus, the third shift promoting region FA23 promotes a third shifting operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in the first chain phase state CS 1.

As seen in fig. 45, in the first shifting operation (second chain phase state CS2), the bicycle chain C is shifted from the bicycle sprocket 212 toward the smaller sprocket 14 by the front derailleur (not shown). The inner chain reverse upstream chamfer 262C promotes the inclination of the inner link plate C1A toward the smaller sprocket 14 with respect to the axial direction D2. The second reverse upstream chamfer 250A promotes the canting of the outer link plate C2A toward the smaller sprocket 14 relative to the axial direction D2. Further, the second downstream tangential face 246A guides the inner link plate C1B in the axial direction D2 toward the smaller sprocket 14. Thus, in the first shifting operation, the bicycle chain C first disengages the bicycle sprocket 212 at the second derailleurs 246.

As shown in FIG. 46, the outer link plate C2B is guided by the contact surface 60A of the raised portion 60 toward the smaller sprocket 14. This causes the inner link plate C1C to move in the axial direction D2 away from the shift facilitating projection 56. Thus, as seen in fig. 46, the bicycle chain C extends from the second derailing tooth 246 when viewed in the axial direction D2. This easily engages the bicycle chain C with the first tooth 234 when the bicycle chain C is in the second chain phase state CS 2. Thus, the third shift promoting region FA23 promotes the first shifting operation of the bicycle chain C from the bicycle sprocket 212 toward the smaller sprocket 14 in the second chain phase state CS 2.

As seen in fig. 47, when the bicycle chain C is shifted from the bicycle sprocket 212 toward the smaller sprocket 14 by the front derailleur (not shown), the bicycle chain C is lifted by the additional shift facilitating protrusion 266 in the second shifting operation. This causes the outer link plate C2G to engage the outer chain receiving tooth 260 and the inner link plate C1G to engage the inner chain receiving tooth 262. The outer chain receiving tooth 260 first receives the bicycle chain C in the second shifting operation. Thus, the first shift facilitating area FA21 facilitates a second shifting operation of the bicycle chain C from the smaller sprocket 14 to the bicycle sprocket 212. The bicycle chain C is in the second chain phase state CS2 (fig. 37) after the second shifting operation is completed. In the present embodiment, since the smaller sprocket 14 only has the second chain phase state CS2, the bicycle chain C is necessarily in the second chain phase state CS2 (fig. 37) after the second shifting operation is completed. When the user engages the bicycle chain C with the bicycle sprocket 212 such that it is in the first chain phase state CS1 but not the second chain phase state CS2, the bicycle chain C is in the first chain phase state CS 1. The second chain phase state CS2 may also be referred to as the regular chain phase state CS1, and the first chain phase state CS1 may also be referred to as the irregular chain phase state CS 2.

Substantially the same effect as the bicycle sprocket 12 of the first embodiment can be obtained for the bicycle sprocket 212.

Third embodiment

A bicycle crank assembly 310 including a bicycle sprocket 312 in accordance with a third embodiment will be described with reference to fig. 48 to 50. The bicycle sprocket 312 has the same structure as the bicycle sprocket 12, except for the raised portions. Accordingly, elements having substantially the same function as elements of the first embodiment are numbered the same herein and will not be described in detail herein for the sake of brevity.

As seen in fig. 48 and 49, the bicycle sprocket 312 includes a sprocket body 30, a plurality of sprocket teeth 32, a shift facilitating protrusion 56, a raised portion 60, a second shift facilitating protrusion 66 and a third shift facilitating protrusion 70.

In the present embodiment, as seen in fig. 49, the bicycle sprocket 312 includes at least one raised portion 360 disposed in at least one drive promoting area FA 2. The at least one raised portion 360 is disposed on a downstream side of one of the at least one first tooth 34 in a drive rotation direction D11, and the bicycle sprocket rotates in the drive rotation direction D11 during pedaling. The at least one raised portion 360 includes a pair of raised portions 360. However, the total number of the convex portions 360 is not limited to the present embodiment. The convex portion 360 has substantially the same structure as the convex portion 60 of the first embodiment. However, the raised portion 360 can have other configurations (e.g., angle and/or axial height of the contact surface) than the raised portion 60, if needed and/or desired.

As described in the first embodiment, the drive promoting area FA2 is configured to promote the holding and driving of the bicycle chain C, rather than the shifting operation. The shift facilitation performance of the drive facilitation area FA2 is lower than that of the shift facilitation area FA 1. In the present embodiment, neither the shift promoting cut surface nor the shift promoting recess nor the shift promoting protrusion is provided in the drive promoting area FA 2. Therefore, the possibility that derailing and receiving of the bicycle chain C is smoothly performed in the drive promoting area FA2 is lower than in the shift promoting area FA 1. The drive promoting area FA2 is defined to include points that are 90 degrees offset from top dead center and bottom dead center of the bicycle crank assembly 310, respectively, in the circumferential direction D1. In other words, the drive promoting area FA2 does not include the top dead center and the bottom dead center of the bicycle crank assembly 310, while the shift promoting area FA1 includes the top dead center and the bottom dead center.

The raised portion 360 is disposed on a downstream side of the first tooth 34X in the driving rotation direction D11 to reduce interference between the first tooth 34X and the bicycle chain C in the second shifting operation. This prevents the bicycle chain C from being unintentionally lifted by the first teeth 34 and then falling off the bicycle sprocket 312 in the second shifting operation. That is, in the second shifting operation, the bicycle chain C can be surely shifted from the smaller sprocket 14 to the bicycle sprocket 312. As seen in FIG. 50, the raised portion 360 moves the bicycle chain C away from the first tooth 34X in the second shifting operation as the raised portion 60 does.

With the bicycle sprocket 312, substantially the same effects as the bicycle sprocket 12 of the first embodiment can be obtained.

Fourth embodiment

A bicycle crank assembly 410 including a bicycle sprocket 412 in accordance with a fourth embodiment will now be described with reference to fig. 51 to 65. The bicycle sprocket 412 has the same structure as the bicycle sprocket 12, except for the plurality of sprocket teeth 32 and the plurality of second sprocket teeth 44. Accordingly, elements having substantially the same function as elements of the first embodiment are numbered the same and will not be described in detail herein for the sake of brevity.

As seen in fig. 51, the bicycle crank assembly 410 includes a bicycle sprocket 412 and a smaller sprocket 414. As seen in fig. 52, the bicycle sprocket 412 includes a sprocket body 30, a plurality of sprocket teeth 432, a shift facilitating protrusion 56, a raised portion 60, a second shift facilitating protrusion 66 and a third shift facilitating protrusion 70.

As shown in fig. 52, the plurality of sprocket teeth 432 includes at least one first tooth 434 and at least one second tooth 436. At least one first tooth 434 is provided on the outer rim 30A to engage the bicycle chain C. At least one second tooth 436 is provided on the outer edge 30A to engage the bicycle chain C. In this embodiment, the at least one first tooth 434 includes a plurality of first teeth 434 disposed on the outer edge 30A to engage the bicycle chain C. The at least one second tooth 436 includes a plurality of second teeth 436 disposed on the outer edge 30A to engage the bicycle chain C. The plurality of first teeth 434 and the plurality of second teeth 436 are alternately arranged in the circumferential direction D1.

As shown in fig. 53, the at least one first tooth 434 has a first chain engagement width W411 defined along the axial direction D2. In this embodiment, first tooth 434 includes a first surface 434A and a first chain engagement surface 434B. The first surface 434A faces the axial direction D2. The first chain engagement surface 434B faces the axial direction D2 and is disposed on an opposite side of the first surface 434A along the axial direction D2. The first chain engagement surface 434B is contactable with a bicycle chain C (e.g., an outer link plate C2). A first chain engagement width W411 is defined between the first surface 434A and the first chain engagement surface 434B in the axial direction D2.

The first tooth 434 has a first center plane CP411, the first center plane CP411 being defined to bisect the first chain engagement width W411 along the axial direction D2. The first center plane CP411 is perpendicular to the rotation center axis a 1. The first center plane CP411 is offset from the first reference center plane CP10 in the axial direction D2. However, the first center plane CP411 may coincide with the first reference center plane CP10 in the axial direction D2.

First tooth 434 includes a first tooth tip portion 434C having a first tooth tip center plane CP 413. The first tooth tip center plane CP413 is perpendicular to the center axis of rotation a 1. The first tip center plane CP413 is offset from the first reference center plane CP10 and the first center plane CP411 in the axial direction D2. However, the first tooth tip center plane CP413 may coincide with at least one of the first reference center plane CP10 and the first center plane CP411 in the axial direction D2. The first tooth 434 has an asymmetrical shape with respect to the first center plane CP411 in the axial direction D2. However, the first tooth 434 may have a symmetrical shape with respect to the first center plane CP411 in the axial direction D2.

As shown in fig. 54, the at least one second tooth 436 has a second chain engagement width W412 defined along the axial direction D2. In this embodiment, the second tooth 436 includes a second chain engagement surface 436A and a second additional chain engagement surface 436B. The second link engagement surface 436A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., an inner link plate C1). The second additional chain engagement surface 436B faces the axial direction D2 and is disposed on an opposite side of the second chain engagement surface 436A along the axial direction D2. The second additional link engagement surface 436B is contactable with a bicycle chain C (e.g., an inner link plate C1). A second chain engagement width W412 is defined between the second chain engagement surface 436A and the second additional chain engagement surface 436B in the axial direction D2.

The second tooth 436 has a second center plane CP412, the second center plane CP412 defined to bisect the second chain engagement width W412 along the axial direction D2. The second central plane CP412 is perpendicular to the rotational central axis a 1. The second center plane CP412 is offset from the first reference center plane CP10 in the axial direction D2. However, the second center plane CP412 may coincide with the first reference center plane CP10 in the axial direction D2. The second center plane CP412 coincides with the first center plane CP 411. However, the second center plane CP412 may be offset from the first center plane CP411 in the axial direction D2.

The second tooth 436 includes a second toe portion 436C having a second toe center plane CP 414. The second tip center plane CP414 is perpendicular to the rotational center axis a 1. The second tip center plane CP414 is offset from the first and second reference center planes CP10 and CP412 in the axial direction D2. However, the second tip center plane CP414 may coincide with at least one of the first reference center plane CP10 and the second center plane CP412 in the axial direction D2. The second tooth 436 has an asymmetrical shape with respect to the second center plane CP412 in the axial direction D2. However, the second teeth 436 may have a symmetrical shape with respect to the second center plane CP412 in the axial direction D2.

In the present embodiment, the second chain engagement width W412 is equal to the first chain engagement width W411. The first chain engagement width W411 and the second chain engagement width W412 are smaller than the inner chain space C11. However, the second chain coupling width W412 may be different from the first chain coupling width W411. One of the first chain coupling width W411 and the second chain coupling width W412 may be equal to or greater than the inner chain space C11.

As shown in fig. 55, the smaller sprocket 414 includes a second sprocket body 42 and a plurality of second sprocket teeth 444. A plurality of second sprocket teeth 444 are disposed on the outer edge 42A of the second sprocket body 42. The plurality of second sprocket teeth 444 includes at least one third tooth 446, at least one fourth tooth 448, and at least one fifth tooth 449. At least one third tooth 446 is provided on the outer edge 42A to engage the bicycle chain C. At least one fourth tooth 448 is provided on the outer edge 42A to engage the bicycle chain C. At least one fifth tooth 449 is provided on the outer rim 42A to engage the bicycle chain C. In the present embodiment, the at least one third tooth 446 includes a plurality of third teeth 446 disposed on the outer edge 42A to engage the bicycle chain C. The at least one fourth tooth 448 includes a plurality of fourth teeth 448 disposed on the outer edge 42A to engage the bicycle chain C. The at least one fifth tooth 449 includes a plurality of fifth teeth 449 disposed on the outer edge 42A to engage the bicycle chain C. The plurality of fourth teeth 448 and the plurality of fifth teeth 449 are alternately arranged in the circumferential direction D1. The third plurality of teeth 446 are respectively disposed between the fourth plurality of teeth 448 and the fifth plurality of teeth 449 in the circumferential direction D1. However, at least one of the plurality of third teeth 446 may be replaced with one of fourth teeth 448 and fifth teeth 449. At least one of the plurality of fourth teeth 448 may be replaced with one of third teeth 446 and fifth teeth 449. At least one of the plurality of fifth teeth 449 may be replaced with one of the third teeth 446 and the fourth teeth 448.

As shown in fig. 56, the at least one third tooth 446 has a third chain engagement width W421 defined along the axial direction D2. In this embodiment, the third tooth 446 includes a third chain engagement surface 446A and a third additional chain engagement surface 446B. The third link engagement surface 446A faces the axial direction D2 and may be in contact with a bicycle chain C (e.g., an inner link plate C1). The third additional chain engagement surface 446B faces the axial direction D2 and is disposed on an opposite side of the third chain engagement surface 446A along the axial direction D2. The third additional link engagement surface 446B is contactable with a bicycle chain C (e.g., an inner link plate C1). A third chain engagement width W421 is defined between the third chain engagement surface 446A and the third additional chain engagement surface 446B in the axial direction D2.

Third tooth 446 has a third center plane CP421, third center plane CP421 being defined as bisecting third chain engagement width W421 in axial direction D2. The third central plane CP421 is perpendicular to the rotation central axis a 1. The third center plane CP421 coincides with the second reference center plane CP20 in the axial direction D2. However, the third center plane CP421 may be offset from the second reference center plane CP20 in the axial direction D2.

The third tooth 446 includes a third tooth tip portion 446C having a third tooth tip center plane CP 422. The third tip center plane CP422 is perpendicular to the center axis of rotation a 1. The third tip center plane CP422 coincides with the second reference center plane CP20 and the third center plane CP421 in the axial direction D2. However, the third tip center plane CP422 may be offset from at least one of the second reference center plane CP20 and the third center plane CP421 in the axial direction D2. The third teeth 446 have a symmetrical shape with respect to the third center plane CP421 in the axial direction D2. However, the third tooth 446 may have an asymmetric shape with respect to the third center plane CP421 in the axial direction D2.

As shown in fig. 57, the at least one fourth tooth 448 has a fourth chain engagement width W422 defined along the axial direction D2. In this embodiment, the fourth tooth 448 includes a fourth surface 448A and a fourth chain engagement surface 448B. The fourth surface 448A faces the axial direction D2. The fourth chain engagement surface 448B faces the axial direction D2 and is disposed on an opposite side of the fourth surface 448A in the axial direction D2. The fourth link engagement surface 448B is contactable with a bicycle chain C (e.g., an outer link plate C2). A fourth chain engagement width W422 is defined between the fourth surface 448A and the fourth chain engagement surface 448B along the axial direction D2.

The fourth tooth 448 has a fourth center plane CP423 that is defined to bisect the fourth chain engagement width W422 along the axial direction D2. The fourth central plane CP423 is perpendicular to the rotation central axis a 1. The fourth center plane CP423 diverges from the second reference center plane CP20 in the axial direction D2 toward the bicycle sprocket 412. However, the fourth center plane CP423 may coincide with the second reference center plane CP20 in the axial direction D2. The fourth center plane CP423 coincides with the third center plane CP 421. However, the fourth center plane CP423 may be offset from the third center plane CP421 in the axial direction D2.

The fourth tooth 448 includes a fourth tooth tip portion 448C having a fourth tooth tip center plane CP 424. The fourth tip center plane CP424 is perpendicular to the center axis of rotation a 1. The fourth tooth tip center plane CP424 is offset from the second and fourth reference center planes CP20 and CP423 in the axial direction D2. However, the fourth tooth tip center plane CP424 may coincide with at least one of the second reference center plane CP20 and the fourth center plane CP423 in the axial direction D2. The fourth tooth 448 has an asymmetrical shape with respect to the fourth center plane CP423 in the axial direction D2. However, the fourth teeth 448 may have a symmetrical shape with respect to the fourth center plane CP423 in the axial direction D2.

As shown in fig. 58, the at least one fifth tooth 449 has a fifth chain engagement width W423 defined in the axial direction D2. In this embodiment, fifth tooth 449 includes a fifth chain engaging surface 449A and a fifth surface 449B. The fifth link engaging surface 449A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., the outer link plate C2). The fifth surface 449B faces the axial direction D2, and is disposed on the opposite side of the fifth chain engagement surface 449A in the axial direction D2. A fifth chain engagement width W423 is defined between the fifth chain engagement surface 449A and the fifth surface 449B in the axial direction D2.

The fifth tooth 449 has a fifth central plane CP425, the fifth central plane CP425 being defined to bisect the fifth chain engaging width W423 along the axial direction D2. The fifth central plane CP425 is perpendicular to the rotational central axis a 1. The fifth center plane CP425 diverges from the second reference center plane CP20 in the axial direction D2 away from the bicycle sprocket 412. However, the fifth center plane CP425 may coincide with the second reference center plane CP20 in the axial direction D2. The fifth central plane CP425 coincides with the third central plane CP 421. However, the fifth central plane CP425 may be offset from the third central plane CP421 in the axial direction D2.

Fifth tooth 449 includes a fifth tooth tip 449C having a fifth tooth tip center plane CP 426. The fifth tooth tip center plane CP426 is perpendicular to the center axis of rotation a 1. The fifth tooth tip center plane CP426 is offset from the second reference center plane CP20 and the fifth center plane CP425 in the axial direction D2. However, the fifth tooth tip center plane CP426 may coincide with at least one of the second reference center plane CP20 and the fifth center plane CP425 in the axial direction D2. Fifth tooth 449 has an asymmetrical shape with respect to fifth central plane CP425 along axial direction D2. However, the fifth teeth 449 may have a symmetrical shape with respect to the fifth central plane CP425 in the axial direction D2.

In the present embodiment, as shown in fig. 56 to 58, the fourth chain engagement width W422 and the fifth chain engagement width W423 are equal to the third chain engagement width W421. The third chain coupling width W421, the fourth chain coupling width W422, and the fifth chain coupling width W423 are smaller than the inner chain space C11. However, at least one of the fourth chain coupling width W422 and the fifth chain coupling width W423 may be different from the third chain coupling width W421. At least one of the third chain coupling width W421, the fourth chain coupling width W422, and the fifth chain coupling width W423 may be equal to or greater than the inner chain space C11.

In the present embodiment, as shown in fig. 52 and 55, the total number of the plurality of sprocket teeth 432 is an even number, and the total number of the plurality of second sprocket teeth 444 is an even number. For example, the total number of the plurality of sprocket teeth 432 is thirty-six, and the total number of the plurality of second sprocket teeth 444 is twenty-four. However, the total number of the plurality of sprocket teeth 432 is not limited to the present embodiment. The total number of the second sprocket teeth 444 is not limited to the present embodiment.

As seen in fig. 52, the bicycle sprocket 412 includes at least one drive promoting area FA 2. In the present embodiment, the at least one drive promoting area FA2 includes a plurality of drive promoting areas FA 2. The drive promoting regions FA2 are disposed outside the shift promoting regions FA1 and between the shift promoting regions FA1 in the circumferential direction D1. However, the total number of the drive promoting areas FA2 is not limited to the present embodiment.

As seen in fig. 59, the plurality of sprocket teeth 432 includes a first derailleur tooth 454 that is disposed on the outer edge 30A of the sprocket body 30 to first disengage the bicycle chain C from the bicycle sprocket 412 in a first shifting operation. In the present embodiment, as seen in fig. 52, the plurality of sprocket teeth 432 includes a plurality of first derailleurs 454 that are respectively disposed in the shift promoting areas to first disengage the bicycle chain C from the bicycle sprocket 412 in the first shifting operation. However, the total number of the first derailing teeth 454 is not limited to the present embodiment.

As seen in fig. 59, the at least one shift facilitating protrusion 56 is at least partially disposed closer to the central axis of rotation a1 than the at least one first tooth 434. One of the at least one first tooth 434 is at least partially disposed closest to the at least one shift facilitating protrusion 56 among the at least one first tooth 434. In this embodiment, the plurality of sprocket teeth 432 includes a first adjacent tooth 458, the first adjacent tooth 458 being closest to the shift facilitating protrusion 56 in the plurality of sprocket teeth 432. In this embodiment, the at least one first tooth 434 includes a first adjacent tooth 458. The first derailing tooth 454 is adjacent to the first adjacent tooth 458 in the drive rotation direction D11 with no additional teeth between the first derailing tooth 454 and the first adjacent tooth 458. However, the positional relationship among the first derailing tooth 454, the shift facilitation protrusion 56, and the first adjacent tooth 458 is not limited to this embodiment.

As shown in fig. 54, the plurality of sprocket teeth 432 includes a reference tooth 462 having a reference tooth center plane CP43, the reference tooth center plane CP43 being defined to bisect the maximum axial width W412 of the reference tooth 462 along the axial direction D2. In the present embodiment, the reference tooth 462 is the second tooth 436. The reference tooth center plane CP43 coincides with the second center plane CP412 of the second tooth 436. As shown in FIG. 53, the first center plane CP411 of the first tooth 434 is offset from the reference tooth center plane CP43 in the axial direction D2 away from the smaller sprocket 414.

As seen in fig. 59, the plurality of sprocket teeth 432 includes at least one receiving tooth 464 that is disposed in the shift facilitating area FA1 to first receive the bicycle chain C in the second shifting operation. The receiving tooth 464 first receives the pair of opposing outer link plates C2 of the bicycle chain C in the second shifting operation. The receiving tooth 464 is disposed on a downstream side of the first derailing tooth 454 in the driving rotation direction D11 with no other tooth between the receiving tooth 464 and the first derailing tooth 454. In the present embodiment, as seen in fig. 52, the at least one receiving tooth 464 includes a plurality of receiving teeth 464 that are respectively disposed in the shift facilitating area FA1 to first receive the bicycle chain C in the second shifting operation. However, the total number of the receiving teeth 464 is not limited to the present embodiment.

As shown in fig. 60, the at least one receiving tooth 464 has a chain engagement width W451 defined along the axial direction D2. In this embodiment, the receiving teeth 464 include a chain engaging surface 464A and a reverse surface 464B. The chain engagement surface 464A faces in the axial direction D2 and is contactable with a bicycle chain C (e.g., an outer link plate C2). The reverse surface 464B faces the axial direction D2 and is disposed on an opposite side of the link-engaging surface 464A in the axial direction D2. A chain engagement width W451 is defined between the chain engagement surface 464A and the reverse surface 464B in the axial direction D2.

The receiving tooth 464 has a central plane CP451, the central plane CP451 being defined to bisect the link-engaging width W451 along the axial direction D2. The central plane CP451 is perpendicular to the rotational central axis a 1. The center plane CP451 is offset from the first reference center plane CP10 in the axial direction D2. However, the center plane CP451 may coincide with the first reference center plane CP10 in the axial direction D2.

Receiving tooth 464 includes a tip 464C having a tip center plane CP 452. The tip center plane CP452 is perpendicular to the center axis of rotation a 1. The tip center plane CP452 is offset from the first reference center plane CP10 in the axial direction D2 and coincides with the center plane CP451 in the axial direction D2. However, the tip center plane CP452 may be offset from the center plane CP451 in the axial direction D2. The receiving tooth 464 has an asymmetrical shape with respect to the center plane CP451 in the axial direction D2. However, the receiving teeth 464 may have a symmetrical shape with respect to the central plane CP451 in the axial direction D2.

As shown in fig. 61 and 62, the first derailing tooth 454 includes a first derailing downstream cut 454A disposed on the first axial surface 38. The first derailing downstream cut surface 454A is provided on the downstream side in the driving rotation direction D11 in the first derailing tooth 454. The first derailing downstream cut surface 454A reduces interference between the first derailing tooth 454 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 454 first disengages the bicycle chain C from the bicycle sprocket 412 in the first shifting operation.

The first derailing tooth 454 includes a first derailing upstream cut 454B disposed on the first axial surface 38. The first derailing upstream tangent plane 454B is provided on the upstream side in the driving rotation direction D11 in the first derailing tooth 454. The first derailing upstream cut surface 454B reduces interference between the first derailing tooth 454 and the bicycle chain C (e.g., the outer link plate C2) when the first derailing tooth 454 first disengages the bicycle chain C from the bicycle sprocket 412 in the first shifting operation.

As shown in fig. 63, the first derailing tooth 454 includes a first receiving downstream cut surface 454C disposed on the first reverse axial surface 40. The first receiving downstream cut surface 454C is provided on the downstream side in the driving rotation direction D11 in the first derailing tooth 454. The first receiving downstream tangent surface 454C reduces interference between the first derailing tooth 454 and the bicycle chain C (e.g., the inner link plate C1) when the receiving tooth 464 first receives the bicycle chain C in the second shifting operation. That is, the first derailing tooth 454 facilitates the reception of the bicycle chain C at the receiving tooth 464 during the second shifting operation.

As shown in fig. 61 and 62, the receiving tooth 464 includes an additional downstream cut 464E disposed on the first axial surface 38. An additional downstream cut face 464E is provided on the downstream side in the receiving tooth 464 in the driving rotation direction D11.

Receiving tooth 464 includes an additional upstream chamfer 464D disposed on first axial surface 38. An additional upstream tangential plane 464D is provided on the upstream side in the receiving tooth 464 in the driving rotation direction D11.

The at least one second shift facilitating protrusion 66 is at least partially disposed closer to the central axis of rotation a1 than the at least one first tooth 434. One of the at least one first tooth 434 is at least partially disposed closest to the at least one second shift facilitating protrusion 66 among the at least one first tooth 434. In this embodiment, the at least one first tooth 434 includes a second adjacent tooth 468 in the plurality of sprocket teeth 432 that is closest to the second shift facilitating protrusion 66. In this embodiment, the at least one first tooth 434 includes a second adjacent tooth 468. The first derailing tooth 454 is adjacent to the second adjacent tooth 468 in the drive rotation direction D11 with no additional teeth between the first derailing tooth 454 and the second adjacent tooth 468. However, the positional relationship among the first derailing tooth 454, the second shift facilitation protrusion 66, and the second adjacent tooth 468 is not limited to this embodiment.

As seen in fig. 59, the at least one third shift facilitating protrusion 70 is at least partially disposed closer to the rotational center axis a1 than the at least one second tooth 436. One of the at least one first tooth 434 is at least partially disposed closest to the at least one third shift facilitating protrusion 70 among the at least one first tooth 434. In the present embodiment, the at least one second tooth 436 includes a third adjacent tooth 472 of the plurality of sprocket teeth 432 that is closest to the third shift facilitating protrusion 70. In this embodiment, the at least one second tooth 436 includes a third adjacent tooth 472. The receiving tooth 464 is adjacent the third adjacent tooth 472 in the drive rotational direction D11, with no additional teeth between the receiving tooth 464 and the third adjacent tooth 472. The third adjacent tooth 472 is disposed between the receiving tooth 464 and the second adjacent tooth 468 in the circumferential direction D1. However, the positional relationship among the receiving teeth 464, the second and third shift facilitating protrusions 66, 70, and the third adjacent teeth 472 is not limited to the present embodiment.

As shown in fig. 63, the third adjacent tooth 472 includes a third derailment upstream chamfer 472A disposed on the first reverse axial surface 40. The third derailing upstream cut surface 472A is provided on the upstream side in the driving rotation direction D11 in the third adjacent tooth 472. The third derailing upstream cut face 472A reduces interference between the third adjacent tooth 472 and the bicycle chain C (e.g., the inner link plate C1) when the first derailing tooth 454 first disengages the bicycle chain C from the bicycle sprocket 412 in the first shifting operation.

As shown in fig. 61 and 62, the third adjacent tooth 472 includes a third receiving upstream chamfer 472B disposed on the first axial surface 38. The third receiving upstream cut surface 472B is disposed on the downstream side in the driving rotation direction D11 in the third adjacent tooth 472. The third receiving upstream chamfer 472B reduces interference between the third adjacent tooth 472 and the bicycle chain C (e.g., the inner link plate C1) when the receiving tooth 464 first receives the bicycle chain C in the second shifting operation.

The third adjacent tooth 472 includes an additional downstream cut surface 472C disposed on the first axial surface 38. An additional downstream cut face 472C is disposed on the downstream side in the receiving tooth 464 in the driving rotation direction D11.

In the present embodiment, as shown in fig. 59, the shift promoting area FA1 is defined from the upstream tooth bottom portion 458T of the first adjacent tooth 458 to the downstream circumferential end portion 74A of the shift promoting recess 74 in the circumferential direction D1. The first shift promoting area FA11 is defined from the upstream tooth bottom portion 458T of the first adjacent tooth 458 to the downstream tooth bottom portion 472T of the third adjacent tooth 472 in the circumferential direction D1. The second shift promoting area FA12 is defined from the upstream tooth bottom portion 454T of the first derailing tooth 454 to the downstream circumferential end portion 74A of the shift promoting recess 74 in the circumferential direction D1. However, the first and second shift facilitation areas FA11 and FA12 are not limited to the present embodiment.

As seen in fig. 64, similar to the second shifting operation of the first embodiment, the outer link plate C2 of the bicycle chain C is moved in the axial direction D2 away from the shift facilitating protrusion 56 by the contact surface 60A of the raised portion 60. This prevents the bicycle chain C from contacting the shift facilitating protrusion 56, as seen in fig. 65. Thus, in the second shifting operation, the bicycle chain C can be positively engaged with the second and third shift facilitating protrusions 66 and 70 without being lifted by the shift facilitating protrusion 56.

Fifth embodiment

A bicycle crank assembly 510 including a bicycle sprocket 512 in accordance with a fifth embodiment will be described with reference to fig. 66 to 68. The bicycle sprocket 512 has the same structure as the bicycle sprocket 412, except for the plurality of sprocket teeth 432 and the raised portion. Accordingly, elements having substantially the same function as elements of the first embodiment are numbered the same herein and will not be described in detail herein for the sake of brevity.

As seen in fig. 66 and 67, the bicycle sprocket 512 includes a sprocket body 30, a plurality of sprocket teeth 432, a shift facilitating protrusion 56, a raised portion 600, a second shift facilitating protrusion 66 and a third shift facilitating protrusion 70. In the present embodiment, as shown in fig. 67, the plurality of sprocket teeth 432 include offset teeth 582.

As shown in fig. 68, the offset teeth 582 have a maximum axial width W513 defined along the axial direction D2. In this embodiment, the deflecting teeth 582 include a sixth chain engaging surface 582A and a sixth surface 582B. The sixth chain engagement surface 582A faces the axial direction D2 and is contactable with a bicycle chain C (e.g., an outer link plate C2). The sixth surface 582B faces the axial direction D2 and is disposed on the opposite side of the sixth chain engagement surface 582A in the axial direction D2. A maximum axial width W513 is defined between the sixth chain engagement surface 582A and the sixth surface 582B in the axial direction D2.

The offset teeth 582 have an offset tooth center plane CP513, the offset tooth center plane CP513 defined as a maximum axial width W513 bisecting the offset teeth 582 along the axial direction D2. The offset tooth center plane CP513 is perpendicular to the center axis of rotation a 1. The offset tooth center plane CP513 is offset from the reference tooth center plane CP43 of the reference tooth 462 in the axial direction D2 toward the smaller sprocket 414. However, the offset tooth center plane CP513 may coincide with the first reference center plane CP10 in the axial direction D2.

The offset teeth 582 include a sixth tooth tip portion 582C having an offset tooth tip center plane CP 514. The offset tip center plane CP514 is perpendicular to the center axis of rotation a 1. The offset tooth tip center plane CP514 is offset from the smaller sprocket 414 in the axial direction D2 from the first reference center plane CP10 and the offset tooth center plane CP 513. The offset tip center plane CP514 is disposed between the first reference center plane CP10 and the offset tooth center plane CP513 in the axial direction D2. However, the offset tip center plane CP514 may coincide with at least one of the first reference center plane CP10 and the offset tooth center plane CP513 in the axial direction D2. The offset teeth 582 have an asymmetrical shape in the axial direction D2 relative to the offset tooth center plane CP 513. However, the offset teeth 582 may have a symmetrical shape with respect to the offset tooth center plane CP513 along the axial direction D2.

In the present embodiment, as seen in fig. 67, the bicycle sprocket 512 includes at least one raised portion 600 disposed in at least one drive promoting area FA 2. The at least one raised portion 600 includes a pair of raised portions 560. However, the total number of the convex portions 560 is not limited to the present embodiment. The convex portion 600 has substantially the same structure as the convex portion 60 of the first embodiment.

The at least one raised portion 600 is disposed on a downstream side of the offset teeth 582 in the driving rotation direction D11, and the bicycle sprocket 512 rotates in the driving rotation direction D11 during pedaling. The second tooth 436X is closest to the raised portion 600 among the plurality of sprocket teeth 432. The second tooth 436X is disposed on the downstream side of the deviating tooth 582 in the driving rotational direction D11 without additional teeth between the second tooth 436X and the deviating tooth 582.

The convex portion 600 is disposed on a downstream side of the first tooth 34X in the driving rotation direction D11 to reduce interference between the first tooth 34X and the bicycle chain C in the second shifting operation. The raised portion 600 moves the bicycle chain C away from the deviating teeth 582 in the second shifting operation. The function of the convex portion 600 is substantially the same as that of the convex portion 60. Therefore, for the sake of brevity, it will not be described in detail herein.

It will be apparent to those skilled in the bicycle art from this disclosure that the above-described embodiments can be combined with one another, at least in part, if needed and/or desired. For example, the bicycle sprockets 12, 212, 312, 412 and 512 can be combined with each of the smaller sprocket 14 and the smaller sprocket 414.

The term "comprises/comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers, and/or steps. This concept also applies to words having similar meanings such as the terms, "having", "including" and their derivatives.

The terms "member," "section," "portion," "element," "body" and "structure," when used in the singular can have the dual meaning of a single part or a plurality of parts.

Ordinal numbers such as "first" and "second" recited in this application are merely labels and do not have other meanings, e.g., a particular order, etc. Further, for example, the term "first element" does not itself imply the presence of "second element," and the term "second element" does not itself imply the presence of "first element.

the term "pair" as used herein may include configurations in which a pair of elements have different shapes or structures from each other, except for configurations in which a pair of elements have the same shape or structure as each other.

The terms "a", "an", "one or more" and "at least one" may be used interchangeably herein.

Finally, terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.