BICYCLE SPRING

Abstract

Bicycle sprocket (12, 212, 312, 412, 512), comprising: a gear ring element (22, 322) comprising a pivot axis (A1), a gear ring body (24) comprising a radially outer rim arranged around the rotational center axis (A1), and a plurality of toothed teeth (26) arranged at the radial outer edge; a first shift-facilitation projection (42) coupled to the sprocket element (22, 322) to engage with an inner connecting link plate (BC1) of a bicycle chain (BC) when the bicycle chain (BC) is shifted from a smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512); and a second shift relief projection (42, 44, 244) coupled to the sprocket element (22, 322) to engage with an outer connecting link plate (BC2) of the bicycle chain (BC) when the bicycle chain (BC) is shifted from the smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512).

Description

[0001] The present invention relates to a bicycle sprocket.

[0002] Cycling is becoming an increasingly popular form of recreation as well as a means of transportation. Furthermore, cycling 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 undergone extensive redesign is the sprocket.

[0003] DE 691 10 800 T2 discloses a bicycle sprocket having a sprocket element comprising a rotational center axis, a sprocket body, and a plurality of sprocket teeth. The sprocket body includes a radially outer edge arranged around the rotational center axis. The plurality of sprocket teeth are arranged on the radially outer edge. Furthermore, the bicycle sprocket includes a first shift-facilitating projection and a second shift-facilitating projection, each coupled to the sprocket element.

[0004] The object of the present invention is to improve the shifting behavior during a shift operation for shifting the bicycle chain from the smaller sprocket to the bicycle sprocket. SUMMARY OF THE INVENTION

[0005] According to a first aspect of the present invention, a bicycle sprocket comprises a sprocket member, a first shift facilitation protrusion, and a second shift facilitation protrusion. The sprocket member includes a rotational center axis, a sprocket body, and a plurality of sprocket teeth. The sprocket body includes a radially outer edge disposed around the rotational center axis. The plurality of sprocket teeth are disposed at the radially outer edge. The first shift facilitation protrusion is coupled to the sprocket member to engage with an inner link plate of a bicycle chain when the bicycle chain is shifted from a smaller sprocket to the bicycle sprocket. The second shift facilitation protrusion is coupled to the sprocket member to engage with an outer link plate of the bicycle chain when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket.

[0006] With the bicycle sprocket according to the first aspect, the first shifting relief protrusion and the second shifting relief protrusion facilitate a first shifting operation in which the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This improves the shifting performance of the bicycle sprocket.

[0007] According to a second aspect of the present invention, the bicycle sprocket according to the first aspect is configured such that the second switch facilitating projection is provided on a downstream side of the first switch facilitating projection in a rotational direction in which the bicycle sprocket rotates during pedaling, without another switch facilitating projection between the first switch facilitating projection and the second switch facilitating projection in the rotational direction.

[0008] With the bicycle sprocket according to the second aspect, it is possible to effectively facilitate the first shifting operation by using the second shift facilitating protrusion in addition to the first shift facilitating protrusion.

[0009] According to a third aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the first shifting-facilitating projection is spaced apart from the second shifting-facilitating projection by a first pitch in a circumferential direction defined about the rotational center axis. The first pitch is substantially equal to a chain pitch of the bicycle chain.

[0010] With the bicycle sprocket according to the third aspect, it is possible to more effectively facilitate the first shifting operation by using the second shift facilitating protrusion in addition to the first shift facilitating protrusion.

[0011] According to a fourth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the plurality of sprocket teeth includes a first adjacent tooth and a second adjacent tooth. The second adjacent tooth is adjacent to the first adjacent tooth without another tooth in a circumferential direction defined about the rotational center axis. The first adjacent tooth is closest to the first shift facilitating protrusion among the plurality of sprocket teeth. The second adjacent tooth is closest to the second shift facilitating protrusion among the plurality of sprocket teeth.

[0012] With the bicycle sprocket according to the fourth aspect, it is possible to narrow a region in which the first switch facilitating projection and the second switch facilitating projection are provided in the rotational direction.

[0013] According to a fifth aspect of the present invention, the bicycle sprocket according to the fourth aspect is configured such that the plurality of sprocket teeth includes a female tooth adjacent to the first adjacent tooth without another tooth between the female tooth and the first adjacent tooth in the circumferential direction. The female tooth is provided on an upstream side of the first adjacent tooth in a rotational direction in which the bicycle sprocket rotates during pedaling. The female tooth includes a tooth root and a tooth tip. The tooth root is coupled to the radially outer edge of the sprocket body. The tooth root has a first axial center defined in an axial direction parallel to the rotational center axis. The tooth tip is provided radially outward from the tooth root with respect to the rotational center axis. The tooth tip has a second axial center defined in the axial direction.The second axial center is provided at an axial position equal to an axial position of the first axial center in the axial direction.

[0014] With the bicycle sprocket according to the fifth aspect, since the second axial center is provided at the axial position equal to the axial position of the first axial center in the axial direction, the bicycle chain is less likely to hit the tooth tip of the receiving tooth when the bicycle chain is shifted between the bicycle sprocket and the smaller sprocket. Thus, it is possible to keep the bicycle chain stable when a pedaling force is transmitted from the bicycle sprocket to the bicycle chain during pedaling without shifting the bicycle chain.

[0015] According to a sixth aspect of the present invention, the bicycle sprocket according to any one of the fourth and fifth aspects is configured such that the plurality of sprocket teeth includes a female tooth adjacent to the first adjacent tooth without another tooth between the female tooth and the first adjacent tooth in the circumferential direction. The female tooth is provided on an upstream side of the first adjacent tooth in a rotational direction in which the bicycle sprocket rotates during pedaling. The female tooth includes a tooth root and a tooth tip. The tooth root is coupled to the radially outer edge of the sprocket body. The tooth root has a first axial center defined in an axial direction parallel to the rotational center axis. The tooth tip is provided radially outward from the tooth root with respect to the rotational center axis. The tooth tip has a second axial center defined in the axial direction.The second axial center is offset from the first axial center in the axial direction.

[0016] With the bicycle sprocket according to the sixth aspect, it is possible to securely hold the bicycle chain with the receiving tooth, which improves the first shifting operation.

[0017] According to a seventh aspect of the present invention, the bicycle sprocket according to any one of the fifth to sixth aspects is configured such that the second axial center is closer in the axial direction than the first axial center to the first shift facilitating projection.

[0018] With the bicycle sprocket according to the seventh aspect, it is possible to more securely hold the bicycle chain with the receiving tooth, which improves the first shift operation.

[0019] According to an eighth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the first shift facilitation protrusion has a first axial length defined by the sprocket member in an axial direction parallel to the rotational center axis. The second shift facilitation protrusion has a second axial length defined by the sprocket member in the axial direction. The first axial length is smaller than the second axial length.

[0020] With the bicycle sprocket according to the eighth aspect, it is possible to reduce the disturbing interaction between the first shift facilitating projection and the bicycle chain during a second shifting operation in which the bicycle chain is shifted from the bicycle sprocket to the smaller sprocket.

[0021] According to a ninth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the first shifting facilitating projection comprises a first coupling body and a projection portion. The first coupling body is coupled to the sprocket member. The projection portion extends radially outward from the first coupling body with respect to the rotational center axis.

[0022] With the bicycle sprocket according to the ninth aspect, the protrusion can easily catch the bicycle chain when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This facilitates the initial shifting of the bicycle chain.

[0023] According to a tenth aspect of the present invention, the bicycle sprocket according to the ninth aspect is configured such that the protrusion part is spaced apart from the sprocket member in an axial direction parallel to the rotational center axis.

[0024] With the bicycle sprocket according to the tenth aspect, the protrusion portion can hold the inner link plate of the bicycle chain between the protrusion portion and the sprocket member when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This can effectively facilitate the initial shifting operation of the bicycle chain.

[0025] According to an eleventh aspect of the present invention, the bicycle sprocket according to any one of the ninth to tenth aspects is configured such that the plurality of sprocket teeth includes a first adjacent tooth that is closest to the first shift facilitating protrusion among the plurality of sprocket teeth. The maximum axial distance is defined between the protrusion portion and the first adjacent tooth in the axial direction and is greater than an axial width of the inner link plate.

[0026] With the bicycle sprocket according to the eleventh aspect, it is possible to reduce the interference between the protrusion part and the bicycle chain during pedaling without switching the bicycle chain. This can reduce noise caused by the interference between the protrusion part and the bicycle chain.

[0027] According to a twelfth aspect of the present invention, the bicycle sprocket according to the eleventh aspect is configured such that the first shift facilitating projection is arranged to maintain a clearance of at least one of between the projection portion and the inner link plate in the axial direction and between the first adjacent tooth and the inner link plate in the axial direction during pedaling.

[0028] With the bicycle sprocket according to the twelfth aspect, it is possible to reduce a resistance force generated by at least one of the protrusion portion and the inner link plate and the first adjacent tooth and the inner link plate. This can reduce noise caused by the interference between the protrusion portion and the bicycle chain.

[0029] According to a thirteenth aspect of the present invention, the bicycle sprocket according to any one of the eleventh to twelfth aspects is configured such that the maximum axial distance is in a range of 0.5 mm to 4.0 mm.

[0030] With the bicycle sprocket according to the thirteenth aspect, it is possible to safely reduce the drag force. This can effectively reduce the noise caused by the interference between the protrusion part and the bicycle chain.

[0031] According to a fourteenth aspect of the present invention, the bicycle sprocket according to any one of the eleventh to thirteenth aspects is configured such that the maximum axial distance is greater than or equal to 1.0 mm.

[0032] With the bicycle sprocket according to the fourteenth aspect, it is possible to reduce the resistance force more safely. This can more effectively reduce noise caused by the interference between the protrusion part and the bicycle chain.

[0033] According to a fifteenth aspect of the present invention, the bicycle sprocket according to any one of the eleventh to fourteenth aspects is configured such that the maximum axial distance is less than or equal to 3.8 mm.

[0034] With the bicycle sprocket according to the fifteenth aspect, it is possible to reduce the resistance force more safely. This can more effectively reduce noise caused by the interference between the protrusion part and the bicycle chain.

[0035] According to a sixteenth aspect of the present invention, the bicycle sprocket according to any one of the eleventh to fifteenth aspects is configured such that the maximum axial distance is in a range of 1.0 mm to 2.0 mm.

[0036] With the bicycle sprocket according to the sixteenth aspect, it is possible to reduce the resistance force more safely. This can more effectively reduce noise caused by the interference between the protrusion part and the bicycle chain. Furthermore, the smaller maximum axial distance can bring the inner link plate closer to the sprocket element. Thus, it is possible to perform the bicycle chain shifting safely.

[0037] According to a seventeenth aspect of the present invention, the bicycle sprocket according to any one of the ninth to sixteenth aspects is configured such that the protrusion part includes a radially inner end, a radially outer end, and a first inclined surface. The radially inner end is coupled to the first coupling body. The radially outer end is provided radially outward from the radially inner end with respect to the rotational center axis. The first inclined surface faces the sprocket member in the axial direction. The first inclined surface is inclined to gradually approach the sprocket member in the axial direction from the radially outer end to the radially inner end.

[0038] With the bicycle sprocket according to the seventeenth aspect, the first inclined surface of the protrusion portion can guide the bicycle chain toward the sprocket member in the axial direction when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This can easily engage the bicycle chain with the first shifting facilitation protrusion and bring the bicycle chain closer to the sprocket member.

[0039] According to an eighteenth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the second shift facilitating protrusion has a second inclined surface facing an opposite side of the sprocket member in the axial direction. The second inclined surface is inclined to gradually approach the sprocket member in the axial direction with respect to the rotational center axis from a radially inner side to a radially outer side.

[0040] With the bicycle sprocket according to the eighteenth aspect, the second inclined surface of the second shifting facilitating protrusion can guide the bicycle chain in the axial direction away from the sprocket member when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This can incline the bicycle chain to easily engage the plurality of sprocket teeth, effectively facilitating the first shifting operation of the bicycle chain.

[0041] According to a nineteenth aspect of the present invention, the bicycle sprocket according to any one of the ninth to eighteenth aspects is configured such that the protrusion part is arranged to at least partially overlap with one of the plurality of sprocket teeth when viewed from an axial direction parallel to the rotational center axis.

[0042] With the bicycle sprocket according to the nineteenth aspect, the protrusion portion is arranged to at least partially overlap one of the plurality of sprocket teeth when viewed from an axial direction parallel to the rotational center axis. This can increase the radial height of the first shifting facilitating protrusion. Accordingly, it is possible to effectively bring the bicycle chain closer to the sprocket member.

[0043] According to a twentieth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the plurality of sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first chain engagement width. The at least one second tooth has a second chain engagement width. The first chain engagement width is smaller than an inner link gap defined between an opposing pair of inner link plates of the bicycle chain. The second chain engagement width is larger than the inner link gap and is smaller than an outer link gap defined between an opposing pair of outer link plates of the bicycle chain.

[0044] With the bicycle sprocket according to the twentieth aspect, it is possible to easily maintain the holding of the bicycle chain with the at least one first tooth and the at least one second tooth.

[0045] According to a twenty-first aspect of the present invention, the bicycle sprocket according to the twentieth aspect is configured such that the at least one first tooth includes a first adjacent tooth that is closest to the first shift facilitating projection among the plurality of sprocket teeth.

[0046] With the bicycle sprocket according to the twenty-first aspect, it is possible to engage the inner link plate of the bicycle chain with the first adjacent tooth during the first shifting operation of the bicycle chain. This causes the inner link plate to engage with the first shift facilitating protrusion during the first shifting operation.

[0047] According to a twenty-second aspect of the present invention, the bicycle sprocket according to the twentieth or twenty-first aspect is configured such that the at least one second tooth includes a second adjacent tooth that is closest to the second shift facilitating projection among the plurality of sprocket teeth.

[0048] With the bicycle sprocket according to the twenty-second aspect, it is possible to engage the outer link plate of the bicycle chain with the second adjacent tooth during the first shifting operation of the bicycle chain. This causes the outer link plate of the bicycle chain to engage with the second shift facilitating protrusion during the first shifting operation.

[0049] According to a twenty-third aspect of the present invention, the bicycle sprocket according to any one of the fourth to twenty-second aspects is configured such that the plurality of sprocket teeth includes a receiving tooth adjacent to the first adjacent tooth without another tooth between the receiving tooth and the first adjacent tooth in a circumferential direction defined about the rotational center axis. The receiving tooth is provided on an upstream side of the first adjacent tooth in a rotational direction in which the bicycle sprocket rotates during pedaling. The receiving tooth has an axial width smaller than the second chain engagement width.

[0050] With the bicycle sprocket according to the twenty-third aspect, it is possible to smoothly engage the bicycle chain on the receiving tooth. This facilitates the initial shifting of the bicycle chain.

[0051] According to a twenty-fourth aspect of the present invention, the bicycle sprocket according to any one of the twenty-second and twenty-third aspects is configured such that the plurality of sprocket teeth includes a receiving tooth adjacent to the first adjacent tooth without another tooth between the receiving tooth and the first adjacent tooth in a circumferential direction defined about the rotational center axis. The receiving tooth is provided on an upstream side of the first adjacent tooth in a rotational direction in which the bicycle sprocket rotates during pedaling. The receiving tooth has a radial length that is smaller than a radial length of the second adjacent tooth.

[0052] With the bicycle sprocket according to the twenty-fourth aspect, it is possible to smoothly mount the bicycle chain on the receiving tooth. This facilitates the initial shifting of the bicycle chain.

[0053] According to a twenty-fifth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the second shift facilitating projection is coupled to the sprocket member to engage with the bicycle chain when the bicycle chain is shifted from the bicycle sprocket to the smaller sprocket.

[0054] With the bicycle sprocket according to the twenty-fifth aspect, it is possible to facilitate a second shifting operation in which the bicycle chain is shifted from the bicycle sprocket to the smaller sprocket.

[0055] According to a twenty-sixth aspect of the present invention, the bicycle sprocket according to any one of the above aspects is configured such that the first shift facilitating projection is arranged not to be sandwiched between an opposing pair of link plates of the bicycle chain when the bicycle chain is shifted from the bicycle sprocket to the smaller sprocket.

[0056] With the bicycle sprocket according to the twenty-sixth aspect, it is possible to smoothly shift the bicycle chain from the bicycle sprocket to the smaller sprocket independently of the first shifting relief projection.

[0057] According to a twenty-seventh aspect of the present invention, a bicycle sprocket comprises a sprocket member and a first shifting facilitation protrusion. The sprocket member includes a rotational center axis, a sprocket body, and a plurality of sprocket teeth. The sprocket body includes a radially outer edge arranged around the rotational center axis. The plurality of sprocket teeth are arranged on the radially outer edge. The first shifting facilitation protrusion is coupled to the sprocket member and is configured to engage between an opposing pair of inner link plates of a bicycle chain when the bicycle chain is shifted from a smaller sprocket to the bicycle sprocket. The first shifting facilitation protrusion includes a first coupling body and a protrusion portion. The first coupling body is coupled to the sprocket member.The projection portion extends radially outward from the first coupling body with respect to the rotational center axis. The plurality of sprocket teeth includes a first adjacent tooth and a receiving tooth. The first adjacent tooth is closest to the first shift facilitating projection among the plurality of sprocket teeth. The receiving tooth is adjacent to the first adjacent tooth without another tooth between the receiving tooth and the first adjacent tooth in a circumferential direction defined about the rotational center axis. The receiving tooth is provided on an upstream side of the first adjacent tooth in a rotational direction in which the bicycle sprocket rotates during pedaling. A maximum axial distance defined between the projection portion and the first adjacent tooth in an axial direction parallel to the rotational center axis is in a range of 0.5 mm to 4.0 mm.

[0058] With the bicycle sprocket according to the twenty-seventh aspect, the maximum axial distance can safely reduce the drag force. This can more effectively facilitate the first gear shift.

[0059] According to a twenty-eighth aspect of the present invention, the bicycle sprocket according to the twenty-seventh aspect is configured such that the maximum axial distance is greater than or equal to 1.0 mm.

[0060] With the bicycle sprocket according to the twenty-eighth aspect, it is possible to reduce the resistance more safely. This can facilitate the first gear shift more effectively.

[0061] According to a twenty-ninth aspect of the present invention, the bicycle sprocket according to the twenty-seventh or twenty-eighth aspect is configured such that the maximum axial distance is less than or equal to 3.8 mm.

[0062] With the bicycle sprocket according to the twenty-ninth aspect, it is possible to reduce the resistance more safely. This can facilitate the first gear shift more effectively.

[0063] According to a thirtieth aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to twenty-ninth aspects is configured such that the maximum axial distance is in a range of 1.0 mm to 2.0 mm.

[0064] With the bicycle sprocket according to the thirtieth aspect, it is possible to reduce the resistance more safely. This can facilitate the first gear shift more effectively.

[0065] According to a thirty-first aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirtieth aspects is configured such that the receiving tooth includes a tooth root and a tooth tip. The tooth root is coupled to the radially outer edge of the sprocket body. The tooth root has a first axial center defined in an axial direction parallel to the rotational center axis. The tooth tip is provided radially outward from the tooth root with respect to the rotational center axis. The tooth tip has a second axial center defined in the axial direction. The second axial center is provided at an axial position equal to an axial position of the first axial center in the axial direction.

[0066] With the bicycle sprocket according to the thirty-first aspect, it is possible to securely accommodate the bicycle chain with the receiving tooth, which improves the first shifting operation.

[0067] According to a thirty-second aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-first aspects is configured such that the receiving tooth includes a root and a tip. The root is coupled to the radially outer edge of the sprocket body. The root has a first axial center defined in an axial direction parallel to the rotational center axis. The tip is provided radially outward from the root with respect to the rotational center axis. The tip has a second axial center defined in the axial direction. The second axial center is offset from the first axial center in the axial direction.

[0068] With the bicycle sprocket according to the thirty-second aspect, it is possible to securely accommodate the bicycle chain with the receiving tooth, which improves the first shifting operation.

[0069] According to a thirty-third aspect of the present invention, the bicycle sprocket according to the thirty-second aspect is configured such that the second axial center is closer in the axial direction than the first axial center to the first shift facilitating projection.

[0070] With the bicycle sprocket according to the thirty-third aspect, it is possible to more securely accommodate the bicycle chain with the receiving tooth, which improves the first shifting operation.

[0071] According to a thirty-fourth aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-third aspects is configured such that the first shift facilitating projection is arranged to maintain a clearance of at least one of between the projection portion and an inner link plate of a bicycle chain in the axial direction and between the first adjacent tooth and the inner link plate in the axial direction during pedaling.

[0072] With the bicycle sprocket according to the thirty-fourth aspect, it is possible to reduce a resistance force generated by at least one of the protrusion portion and the inner link plate and the first adjacent tooth and the inner link plate. This can effectively facilitate the first shifting operation.

[0073] According to a thirty-fifth aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-fourth aspects is configured such that the protrusion part includes a radially inner end, a radially outer end, and a first inclined surface. The radially inner end is coupled to the first coupling body. The radially outer end is provided radially outward from the radially inner end with respect to the rotational center axis. The first inclined surface faces the sprocket member in the axial direction. The first inclined surface is inclined so as to approach the sprocket member in the axial direction from the radially outer end to the radially inner end.

[0074] With the bicycle sprocket according to the thirty-fifth aspect, the first inclined surface of the protrusion portion can guide the bicycle chain in the axial direction toward the sprocket member when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This can effectively facilitate the first shifting operation of the bicycle chain.

[0075] According to a thirty-sixth aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-fifth aspects further comprises a second shift facilitation protrusion coupled to the sprocket member. The second shift facilitation protrusion includes a second inclined surface facing an opposite side of the sprocket member in the axial direction. The second inclined surface is inclined to gradually approach the sprocket member in the axial direction with respect to the rotational center axis from a radially inner side to a radially outer side.

[0076] With the bicycle sprocket according to the thirty-sixth aspect, the second inclined surface of the second shifting facilitating protrusion can guide the bicycle chain in the axial direction away from the sprocket member when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. This can incline the bicycle chain to easily engage the plurality of sprocket teeth, effectively facilitating the first shifting operation of the bicycle chain.

[0077] According to a thirty-seventh aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-sixth aspects is configured such that the protrusion part is arranged to at least partially overlap with one of the plurality of sprocket teeth when viewed from an axial direction parallel to the rotational center axis.

[0078] With the bicycle sprocket according to the thirty-seventh aspect, it is possible to easily hold the inner link plate of the bicycle chain between the projection part and the one of the plurality of sprocket teeth when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket.

[0079] According to a thirty-eighth aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to thirty-seventh aspects is configured such that the plurality of sprocket teeth includes at least one first tooth and at least one second tooth. The at least one first tooth has a first chain engagement width. The at least one second tooth has a second chain engagement width. The first chain engagement width is smaller than an inner link gap defined between an opposing pair of inner link plates of the bicycle chain. The second chain engagement width is larger than the inner link gap and is smaller than an outer link gap defined between an opposing pair of outer link plates of the bicycle chain.

[0080] With the bicycle sprocket according to the thirty-eighth aspect, it is possible to easily maintain the holding of the bicycle chain with the at least one first tooth and the at least one second tooth.

[0081] According to a thirty-ninth aspect of the present invention, the bicycle sprocket according to any one of the fourth to thirty-eighth aspects is configured such that the at least one first tooth includes the first adjacent tooth that is closest to the first shift facilitating projection among the plurality of sprocket teeth.

[0082] With the bicycle sprocket according to the thirty-ninth aspect, it is possible to engage the inner link plate of the bicycle chain with the first adjacent tooth during the first shifting operation of the bicycle chain. This causes the inner link plate to engage with the first shift facilitating protrusion during the first shifting operation.

[0083] According to a fortieth aspect of the present invention, the bicycle sprocket according to any one of the twentieth to thirty-ninth aspects further comprises a second shift facilitation protrusion coupled to the sprocket member. The at least one second tooth includes a second adjacent tooth that is closest to the second shift facilitation protrusion among the plurality of sprocket teeth.

[0084] With the bicycle sprocket according to the fortieth aspect, it is possible to engage the outer link plate of the bicycle chain with the second adjacent tooth during the first shifting operation of the bicycle chain. This causes the outer link plate of the bicycle chain to engage with the second shift facilitating protrusion during the first shifting operation.

[0085] According to a forty-first aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to fortieth aspects is configured such that the receiving tooth has an axial width smaller than the second chain engagement width.

[0086] With the bicycle sprocket according to the forty-first aspect, it is possible to smoothly engage the bicycle chain on the receiving tooth. This facilitates the initial shifting of the bicycle chain.

[0087] According to a forty-second aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to forty-first aspects is configured such that the receiving tooth has a radial length smaller than a radial length of the second adjacent tooth.

[0088] With the bicycle sprocket according to the forty-second aspect, it is possible to smoothly engage the bicycle chain on the receiving tooth. This facilitates the initial shifting of the bicycle chain.

[0089] According to a forty-third aspect of the present invention, the bicycle sprocket according to any one of the twenty-seventh to forty-second aspects is configured such that the first shift facilitating projection is arranged not to be sandwiched between an opposing pair of link plates of the bicycle chain when the bicycle chain is shifted from the bicycle sprocket to the smaller sprocket.

[0090] With the bicycle sprocket according to the forty-third aspect, it is possible to switch the bicycle chain smoothly from the bicycle sprocket to the smaller sprocket independently of the first shifting relief projection.

[0091] According to a forty-fourth aspect of the present invention, a bicycle sprocket comprises a sprocket member and at least one shift facilitation protrusion. The sprocket member includes a rotational center axis, a sprocket body, and a plurality of sprocket teeth. The sprocket body includes a radially outer edge disposed around the rotational center axis. The plurality of sprocket teeth are disposed at the radially outer edge. The at least one shift facilitation protrusion is coupled to the sprocket member to engage a link plate of a bicycle chain when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. The plurality of sprocket teeth includes at least one first tooth and at least one second tooth. The at least one first tooth has a first chain engagement width. The at least one second tooth has a second chain engagement width.The first chain engagement width is smaller than an inner link gap defined between an opposing pair of inner link plates of the bicycle chain. The second chain engagement width is larger than the inner link gap and is smaller than an outer link gap defined between an opposing pair of outer link plates of the bicycle chain. The plurality of sprocket teeth includes a receiving tooth configured to first engage the bicycle chain when the bicycle chain is shifted from the smaller sprocket to the bicycle sprocket. The receiving tooth is provided on an upstream side of the at least one shift facilitating projection in a rotational direction in which the bicycle sprocket rotates during pedaling. The receiving tooth includes a tooth root and a tooth tip.The tooth root is coupled to the radially outer edge of the ring gear body. The tooth root has a first axial center defined in an axial direction parallel to the rotational center axis. The tooth tip is positioned radially outward from the tooth root with respect to the rotational center axis. The tooth tip has a second axial center defined in the axial direction. The second axial center is offset from the first axial center in the axial direction.

[0092] With the bicycle sprocket according to the forty-fourth aspect, it is possible to securely accommodate the bicycle chain with the receiving tooth, which improves the first shifting operation.

[0093] According to a forty-fifth aspect of the present invention, the bicycle sprocket according to the forty-fourth aspect is configured such that the second axial center is closer in the axial direction than the first axial center to the at least one shift facilitating projection.

[0094] With the bicycle sprocket according to the forty-fifth aspect, it is possible to accommodate the bicycle chain more securely with the receiving tooth, which improves the first shifting operation.

[0095] According to a forty-sixth aspect of the present invention, the bicycle sprocket according to the forty-fourth or forty-fifth aspect is configured such that the second axial center is farther away in the axial direction from the at least one shift facilitating projection than the first axial center.

[0096] According to a forty-seventh aspect of the present invention, the bicycle sprocket according to any one of the forty-fourth to forty-sixth aspects is configured such that the receiving tooth has a radial length that is smaller than a radial length of the at least one second tooth.

[0097] With the bicycle sprocket according to the forty-seventh aspect, it is possible to smoothly mount the bicycle chain on the receiving tooth. This facilitates the initial shifting of the bicycle chain. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] A more complete appreciation of the invention and many of its attendant advantages will be obtained as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. Fig. 1 is a side view of a bicycle sprocket assembly including a bicycle sprocket according to a first embodiment. Fig. 2 is another side view of the Fig. 1 shown bicycle sprocket assembly. Fig. 3 is a perspective view of the Fig. 1, wherein a sprocket mounting element is omitted. Fig. 4 is another perspective view of the Fig. 1, with the sprocket mounting member omitted. Fig. 5 is a side view of the bicycle sprocket shown in Fig. 1 shown bicycle sprocket assembly. Fig. 6 is a cross-sectional view of the bicycle sprocket along the line VI-VI of Fig. 5. Fig. 7 is a cross-sectional view of the bicycle sprocket along the line VII-VII of Fig. 5. Fig. 8 is a side view of a smaller gear ring of the Fig. 1 shown bicycle sprocket assembly. Fig. 9 is a cross-sectional view of the smaller gear ring along the line IX-IX of Fig. 8. Fig. 10 is a cross-sectional view of the smaller gear ring along the line XX of Fig. 8. Fig. 11 is a side view of the Fig. 1 shown bicycle sprocket assembly. Fig. 12 is a partial perspective view of the Fig. 1 shown bicycle sprocket assembly. Fig. 13 is another partial perspective view of the Fig. 1 shown bicycle sprocket assembly. Fig. 14 is a side view of the Fig. 1 shown bicycle sprocket assembly with a bicycle chain (an upshift mechanism). Fig. 15 is a cross-sectional view of the bicycle sprocket assembly taken along line XV-XV of Fig. 14 (the upshift operation). Fig. 16 is a cross-sectional view of the bicycle sprocket assembly taken along line XVI-XVI of Fig. 14 (the upshift operation). Fig. 17 is a partially enlarged perspective view of the Fig. 1 shown bicycle sprocket assembly. Fig. 18 is another partially enlarged perspective view of the Fig. 1 shown bicycle sprocket assembly. Fig. 19 is an enlarged partial cross-sectional view of the Fig. 16 shown bicycle sprocket assembly. Fig. 20 is a cross-sectional view of the bicycle sprocket assembly (a downshift actuator). Fig. 21 is a partially enlarged cross-sectional view of the bicycle sprocket assembly (the downshifting mechanism). Fig. 22 is a partial cross-sectional view of the bicycle sprocket assembly taken along line XXII-XXII of Fig. 14 (the upshift operation). Fig. 23 is a plan view of the Fig. 1 shown bicycle sprocket assembly with the bicycle chain (the upshift mechanism). Fig. 24 is a partially enlarged cross-sectional view of the bicycle sprocket assembly (after downshifting operation). Fig. 25 is a side view of the Fig. 1 shown bicycle sprocket assembly with the bicycle chain (the downshift mechanism). Fig. 26 is a plan view of the Fig. 1 shown bicycle sprocket assembly with the bicycle chain (the downshift mechanism). Fig. 27 is a side view of a bicycle sprocket assembly including a bicycle sprocket according to a second embodiment. Fig. 28 is a partial side view of the Fig. 27 shown bicycle sprocket assembly. Fig. 29 is a partial perspective view of the Fig. 27 shown bicycle sprocket assembly. Fig. 30 is a partially enlarged perspective view of the Fig. 27 shown bicycle sprocket assembly. Fig. 31 is another partially enlarged perspective view of the Fig. 27 shown bicycle sprocket assembly. Fig. 32 is a partial cross-sectional view of the bicycle sprocket assembly taken along line XXXII-XXXII of Fig. 28 (the upshift operation). Fig. 33 is a partial cross-sectional view of the bicycle sprocket assembly taken along line XXXIII-XXXIII of Fig. 28 (the upshift operation). Fig. 34 is a side view of a bicycle sprocket assembly including a bicycle sprocket according to a third embodiment. Fig. 35 is a partial cross-sectional view of the bicycle sprocket assembly taken along line XXXV-XXXV of Fig. 34 (the upshift operation). Fig. 36 is a side view of a bicycle sprocket assembly including a bicycle sprocket according to a fourth embodiment. Fig. 37 is a partial perspective view of the Fig. 36 shown bicycle sprocket assembly. Fig. 38 is a partial cross-sectional view of the bicycle sprocket assembly taken along line XXXVIII-XXXVIII of Fig. 37 (the downshift operation). Fig. 39 is a partial perspective view of a bicycle sprocket assembly according to a modification of the fourth embodiment. DESCRIPTION OF THE EMBODIMENTS

[0099] The embodiment(s) will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. First embodiment

[0100] If one initially refers to Fig. 1, a bicycle sprocket assembly 10 includes a bicycle sprocket 12 according to a first embodiment. The bicycle sprocket 12 has a rotational center axis A1. The bicycle sprocket 12 is rotatable relative to a bicycle frame (not shown) about the rotational center axis A1. The bicycle sprocket 12 engages with a bicycle chain BC to transmit a rotational drive force F1 to the bicycle chain BC. The bicycle sprocket assembly 10 includes a smaller sprocket 14. The smaller bicycle sprocket 14 engages with the bicycle chain BC to transmit the rotational drive force F1 to the bicycle chain BC. The smaller sprocket 14 has an outer diameter that is smaller than an outer diameter of the bicycle sprocket 12.While the bicycle sprocket assembly 10 in this embodiment includes the bicycle sprocket 12 and the smaller sprocket 14, the bicycle sprocket assembly 10 may include at least one additional sprocket in addition to the bicycle sprocket 12 and the smaller sprocket 14. In this embodiment, the bicycle sprocket assembly 10 is a front sprocket assembly. However, structures of the bicycle sprocket assembly 10 may be applied to a rear sprocket assembly. The bicycle chain BC is switched between the bicycle sprocket 12 and the smaller sprocket 14 by a switching device such as a derailleur (not shown).

[0101] In the present application, the following directional terms "front," "rear," "forward," "backward," "left," "right," "across," "upward," and "downward," as well as any other similar directional terms, refer to those directions determined based on a user (e.g., a rider) sitting on a saddle (not shown) of a bicycle, for example, facing bicycle handlebars (not shown). Accordingly, as used to describe the bicycle sprocket 12 of the bicycle sprocket assembly 10, these terms should be interpreted relative to the bicycle equipped with the bicycle sprocket 12 as being in an upright riding position on a horizontal surface.

[0102] As in the Fig. 1 and Fig. As shown in Figure 2, the bicycle sprocket assembly 10 includes a sprocket mounting member 16, a crank axle CA1, a right crank arm CA2, and a left crank arm CA3. The sprocket mounting member 16 includes crank connecting arms 18. The bicycle sprocket 12 includes crank mounting portions 19. The smaller sprocket 14 includes additional crank mounting portions 20. The crank connecting arms 18 are each attached to the crank mounting portions 19 by attachment members such as bolts (not shown). The additional crank mounting portions 20 are attached to the sprocket mounting member 16 by attachment members such as bolts (not shown).

[0103] The right crank arm CA2 and the left crank arm CA3 are attached to the crank axle CA1. The right crank arm CA2 and the left crank arm CA3 are mounted on the bicycle frame via the crank axle CA1 so as to be rotatable about the rotational center axis A1. The sprocket mounting member 16 is mounted on the right crank arm CA2 so as to be integrally rotatable with the right crank arm CA2 about the rotational center axis A1. The sprocket mounting member 16 may also be provided integrally with the right crank arm CA2 as a one-piece, unitary member. Namely, the bicycle sprocket 12 is integrally rotatable about the rotational center axis A1 with the sprocket mounting member 16 and the right crank arm CA2. The bicycle sprocket 12 is rotatable about the rotational center axis A1 in a rotational direction D11 during pedaling. The rotational direction D11 is defined along a circumferential direction D1 defined around the rotational center axis A1.

[0104] As in the Fig. 3 and Fig. 4, the smaller sprocket 14 is adjacent to the bicycle sprocket 12, without another sprocket between the smaller sprocket 14 and the bicycle sprocket 12. The smaller sprocket 14 is adjacent to the bicycle sprocket 12 in an axial direction D2 that is parallel to the rotational center axis A1, without another sprocket between the smaller sprocket 14 and the bicycle sprocket 12.

[0105] As in Fig. 5, the bicycle sprocket 12 includes a sprocket member 22. The sprocket member 22 includes the rotational center axis A1, a sprocket body 24, and a plurality of sprocket teeth 26. The sprocket member 22 is rotatable relative to the bicycle frame (not shown) in the rotational direction D11 during pedaling. The sprocket body 24 includes a radially outer edge disposed around the rotational center axis A1. The plurality of sprocket teeth 26 are disposed at the radially outer edge of the sprocket body 24. The plurality of sprocket teeth 26 are coupled to the sprocket body 24 to engage the bicycle chain BC to transmit the rotational drive force F1 to the bicycle chain BC. The plurality of sprocket teeth 26 includes at least one first tooth 28 and at least one second tooth 30. In this embodiment, the plurality of sprocket teeth 26 includes a plurality of first teeth 28 and a plurality of second teeth 30.Preferably, the first teeth 28 and the second teeth 30 are arranged alternately in the circumferential direction D1 of the bicycle sprocket 12.

[0106] As in Fig. 6, the at least one first tooth 28 has a first chain engagement width W1. Each of the first teeth 28 has the first chain engagement width W1. As shown in Fig. 7, the at least one second tooth 30 has a second chain engagement width W2. Each of the second teeth 30 has the second chain engagement width W2. As shown in the Fig. 6 and Fig. As seen in Figure 7, the first chain engagement width W1 is smaller than an inner link gap BC11 defined between an opposing pair of inner link plates BC1 of the bicycle chain BC. The second chain engagement width W2 is larger than the inner link gap BC11 and is smaller than an outer link gap BC21 defined between an opposing pair of outer link plates BC2 of the bicycle chain BC. The inner link plate BC1 may also be referred to as a link plate BC1. The outer link plate BC2 may also be referred to as a link plate BC2. The sprocket member 22 includes a first axial surface S1 and a second axial surface S2 opposite the first axial surface S1 in the axial direction D2.The first axial surface S1 is closer to the smaller gear ring 14 in the axial direction D2 than the second axial surface S2.

[0107] As in Fig. 6, the at least one first tooth 28 includes a first axial end 28A and a first opposite axial end 28B opposite the first axial end 28A in the axial direction D2. The first axial end 28A and the first opposite axial end 28B can be brought into contact with the inner link plate BC1 of the bicycle chain BC. The first chain engagement width W1 is defined between the first axial end 28A and the first opposite axial end 28B in the axial direction D2. In this embodiment, each of the first teeth 28 includes the first axial end 28A and the first opposite axial end 28B opposite the first axial end 28A in the axial direction D2. For each of the first teeth 28, the first chain engagement width W1 is defined between the first axial end 28A and the first opposite axial end 28B in the axial direction D2.The first axial end 28A is disposed on the first axial surface S1. The first opposite axial end 28B is disposed on the second axial surface S2.

[0108] As in Fig. 7, the at least one second tooth 30 includes a second axial end 30A and a second opposite axial end 30B opposite the second axial end 30A in the axial direction D2. The second axial end 30A and the second opposite axial end 30B can be brought into contact with the outer link plate BC2 of the bicycle chain BC. The second chain engagement width W2 is defined between the second axial end 30A and the second opposite axial end 30B in the axial direction D2. In this embodiment, each of the second teeth 30 includes the second axial end 30A and the second opposite axial end 30B opposite the second axial end 30A in the axial direction D2. For each of the second teeth 30, the second chain engagement width W2 is defined between the second axial end 30A and the second opposite axial end 30B in the axial direction D2.The second axial end 30A is disposed on the first axial surface S1. The second opposite axial end 30B is disposed on the second axial surface S2.

[0109] As in Fig. As shown in Figure 8, the smaller sprocket 14 includes an additional sprocket body 32 and a plurality of additional sprocket teeth 36. The additional sprocket body 32 has an annular shape. The plurality of additional sprocket teeth 36 are arranged on the radially outer edge of the additional sprocket body 32. The plurality of additional sprocket teeth 36 are coupled to the additional sprocket body 32 to engage with the bicycle chain BC to transmit the rotational drive force F1 to the bicycle chain BC. The plurality of additional sprocket teeth 36 are arranged at a constant pitch in the circumferential direction D1.

[0110] The plurality of additional sprocket teeth 36 includes at least one first additional tooth 38 and at least one second additional tooth 40. In this embodiment, the plurality of additional sprocket teeth 36 includes a plurality of first additional teeth 38 and a plurality of second additional teeth 40. Preferably, the first additional teeth 38 and the second additional teeth 40 are arranged alternately in the circumferential direction D1, which is defined around the rotational center axis A1. A total number of the plurality of additional sprocket teeth 36 of the smaller sprocket 14 is smaller than a total number of the plurality of sprocket teeth 26 of the bicycle sprocket 12.

[0111] As in Fig. 9, the at least one first additional tooth 38 has a third chain engagement width W3. The third chain engagement width W3 is defined in the axial direction D2, as is the first chain engagement width W1 of the first tooth 28. Each of the first additional teeth 38 has the third chain engagement width W3. As shown in Fig. 10, the at least one second additional tooth 40 has a fourth chain engagement width W4. The fourth chain engagement width W4 is defined in the axial direction D2, as is the second chain engagement width W2 of the second tooth 30. Each of the second additional teeth 40 has the fourth chain engagement width W4. As shown in the Fig. 9 and Fig. As can be seen in Figure 10, the third chain engagement width W3 is smaller than the inner link gap BC11. The fourth chain engagement width W4 is larger than the inner link gap BC11 and smaller than the outer link gap BC21.

[0112] As in Fig. 11, the bicycle sprocket 12 includes a first switch relief projection 42 and a second switch relief projection 44. As shown in Fig. As shown in Figure 5, in this embodiment, the bicycle sprocket 12 includes a plurality of first shift facilitation protrusions 42 and a plurality of second shift facilitation protrusions 44. However, the total number of the first shift facilitation protrusions 42 is not limited to this embodiment. The total number of the second shift facilitation protrusions 44 is not limited to this embodiment.

[0113] As in the Fig. 12 and Fig. 13, the first switch facilitation protrusion 42 is coupled to the gear ring member 22. The second switch facilitation protrusion 44 is coupled to the gear ring member 22. In this embodiment, each of the first switch facilitation protrusion 42 and the second switch facilitation protrusion 44 is a separate member from the gear ring member 22. However, at least one of the first switch facilitation protrusion 42 and the second switch facilitation protrusion 44 may be provided integrally with the gear ring member 22 as a one-piece, unitary member. Further, the first switch facilitation protrusion 42 is a separate member from the second switch facilitation protrusion 44. However, the first switch facilitation protrusion 42 may be provided integrally with the second switch facilitation protrusion 44 as a one-piece, unitary member.The first switch relief protrusion 42 may also be referred to as a switch relief protrusion 42. The second switch relief protrusion 44 may also be referred to as a switch relief protrusion 44.

[0114] The second shift facilitation protrusion 44 is provided on a downstream side of the first shift facilitation protrusion 42 in the rotational direction D11 in which the bicycle sprocket 12 rotates during pedaling, without another shift facilitation protrusion between the first switch facilitation protrusion 42 and the second switch facilitation protrusion 44 in the rotational direction D11. However, the arrangement of the first and second switch facilitation protrusions 42 and 44 is not limited to this embodiment. The second switch facilitation protrusion 44 may be provided on an upstream side of the first switch facilitation protrusion 42 in the rotational direction D11, without another switch facilitation protrusion between the first switch facilitation protrusion 42 and the second switch facilitation protrusion 44 in the rotational direction D11.Furthermore, a further switch facilitating projection may be arranged between the first and second switch facilitating projections 42 and 44.

[0115] As in the Fig. 11 to 13, the plurality of ring gear teeth 26 includes a first adjacent tooth 46 and a second adjacent tooth 48. The at least one first tooth 28 includes the first adjacent tooth 46 that is closest to the first switch facilitating projection 42 of the plurality of ring gear teeth 26. The at least one second tooth 30 includes the second adjacent tooth 48 that is closest to the second switch facilitating projection 44 of the plurality of ring gear teeth 26. The second adjacent tooth 48 is adjacent to the first adjacent tooth 46 without another tooth in the circumferential direction D1 with respect to the rotational center axis A1. The first adjacent tooth 46 is closest to the first switch facilitating projection 42 of the plurality of ring gear teeth 26. The second adjacent tooth 48 is closest to the second switch facilitating projection 44 of the plurality of ring gear teeth 26.The first adjacent tooth 46 is disposed radially outward from the first switch facilitating projection 42. The second adjacent tooth 48 is disposed radially outward from the second switch facilitating projection 44.

[0116] Fig. 14 shows a positional relationship between the bicycle chain BC, the bicycle sprocket 12, and the smaller sprocket 14 during a shifting operation (an upshifting operation) in which the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. As shown in Fig. As can be seen in Figure 14, the first shift relief protrusion 42 is spaced apart from the second shift relief protrusion 44 by a first pitch P1 in the circumferential direction D1 defined about the rotational center axis A1. The first pitch P1 is substantially equal to a chain pitch of the bicycle chain BC. However, the first pitch P1 may differ from the chain pitch of the bicycle chain BC.

[0117] As in the Fig. 14 and Fig. 15, the second shift facilitation protrusion 44 is coupled to the sprocket member 22 to engage with the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. In this embodiment, the second shift facilitation protrusion 44 is coupled to the sprocket member 22 to engage with the outer link plate BC2 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The second shift facilitation protrusion 44 is coupled to the sprocket member 22 to engage with an intermediate portion BC23 ( Fig. 14) of the outer link plate BC2 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The second shift facilitating projection 44 is partially inserted into the outer link gap BC21 of the opposing pair of outer link plates BC2 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

[0118] As in the Fig. 14 and Fig. 16, the first shift facilitation protrusion 42 is coupled to the sprocket member 22 to engage with the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. In this embodiment, the first shift facilitation protrusion 42 is coupled to the sprocket member 22 to engage with the inner link plate BC1 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The first shift facilitation protrusion 42 is coupled to the sprocket member 22 to engage with an intermediate portion BC13 ( Fig. 14) of the inner link plate BC1 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The first shift facilitating projection 42 is partially inserted into the inner link space BC11 of the opposed pair of inner link plates BC1 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

[0119] As in Fig. 16, the first switch facilitating protrusion 42 has a first axial length L1 defined by the ring gear member 22 in the axial direction D2, which is parallel to the rotational center axis A1. The second switch facilitating protrusion 44 has a second axial length L2 defined by the ring gear member 22 in the axial direction D2. The first axial length L1 is less than the second axial length L2. In this embodiment, the first axial length L1 is defined by the first axial end 28A of the first tooth 28 (the first adjacent tooth 46) in the axial direction D2. The second axial length L2 is defined by the first axial end 28A of the first tooth 28 (the first adjacent tooth 46) in the axial direction D2.

[0120] As in the Fig. 17 to 19, the first shift facilitating protrusion 42 includes a first coupling body 42A and a protrusion portion 42B. The first coupling body 42A is coupled to the sprocket member 22. The protrusion portion 42B extends radially outward from the first coupling body 42A with respect to the rotational center axis A1. The protrusion portion 42B is spaced from the sprocket member 22 in the axial direction D2, which is parallel to the rotational center axis A1. In this embodiment, the protrusion portion 42 is spaced from the first tooth 28 (the first adjacent tooth 46) in the axial direction D2. The protrusion portion 42B can be brought into contact with the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

[0121] The first coupling body 42A comprises a first base body 42A1, a first head part 42A2 and a first connecting part 42A3 (see Fig. 19). The first base body 42A1 is arranged on the first axial surface S1. The protrusion part 42B extends radially outward from the first base body 42A1 with respect to the rotational center axis A1. The first base body 42A1 can be brought into contact with the inner link plate BC1 of the bicycle chain BC. The first head part 42A2 is arranged on the second axial surface S2. The first connecting part 42A3 connects the first head part 42A2 to the first base body 42A1 and extends through a first fastening hole 22A of the sprocket member 22. The first coupling body 42A has a first center axis A4 extending in the axial direction D2. While the first center axis A4 of the first coupling body 42A is parallel to the axial direction D2 in this embodiment, the first center axis A4 may be non-parallel to the axial direction D2.The first base body 42A1 has an outer diameter that is larger than an outer diameter of the first connecting part 42A3. The first head part 42A2 has an outer diameter that is larger than the outer diameter of the first head part 42A3. The first base body 42A1, the first head part 42A2, and the first connecting part 42A3 constitute a rivet. However, the first switch facilitating projection 42 can be coupled to the gear ring element 22 with other coupling structures.

[0122] As in Fig. As seen in Fig. 19, the first switch relief projection 42 is arranged to maintain a clearance of at least one of between the projection portion 42B and the inner link plate BC1 in the axial direction D2 and between the first adjacent tooth 46 and the inner link plate BC1 in the axial direction D2 during pedal operation. A maximum axial distance L3 defined between the projection portion 42B and the first adjacent tooth 46 in the axial direction D2 is greater than an axial width W5 of the inner link plate BC1.

[0123] The maximum axial distance L3 is in a range from 0.5 mm to 4.0 mm. The maximum axial distance L3 is preferably greater than or equal to 1.0 mm. The maximum axial distance L3 is preferably less than or equal to 3.8 mm. The maximum axial distance L3 is preferably in a range from 1.0 mm to 2.0 mm. However, the maximum axial distance L3 may be in a range that differs from the above ranges.

[0124] As in the Fig. 17 to 19, the projection part 42B includes a radially inner end 42C, a radially outer end 42D, and a first inclined surface 42E. The radially inner end 42C is coupled to the first coupling body 42A. The radially outer end 42D is provided radially outward from the radially inner end 42C with respect to the rotational center axis A1. The first inclined surface 42E faces the sprocket member 22 in the axial direction D2. The first inclined surface 42E is inclined so as to gradually approach the sprocket member 22 in the axial direction D2 from the radially outer end 42D to the radially inner end 42C. The first inclined surface 42E guides the inner link plate BC1 of the bicycle chain BC to the first adjacent tooth 46 in the axial direction D2 when the first shift facilitating projection 42 engages with the bicycle chain BC.

[0125] As in Fig. As can be seen in Figure 11, the protrusion portion 42B is arranged to at least partially overlap one of the plurality of ring gear teeth 26 when viewed from the axial direction D2, which is parallel to the rotational center axis A1. In this embodiment, the protrusion portion 42B is arranged to partially overlap the first adjacent tooth 46 when viewed from the axial direction D2, which is parallel to the rotational center axis A1.

[0126] As in Fig. As shown in Fig. 19, the first shift facilitating protrusion 42 is engaged between an opposing pair of connecting link plates of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. In this embodiment, the first shift facilitating protrusion 42 is engaged between the opposing pair of inner connecting link plates BC1 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

[0127] As in Fig. As shown in Fig. 20, the first shift facilitation protrusion 42 is arranged not to be interposed between an opposing pair of connecting link plates of the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. In this embodiment, the first shift facilitation protrusion 42 is arranged not to be interposed between the opposing pair of inner connecting link plates BC1 of the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14 (i.e., during a downshift operation).

[0128] As in the Fig. 17, Fig. 18 and Fig. As seen in Fig. 21, the second shift facilitating protrusion 44 includes a second inclined surface 44E facing an opposite side of the sprocket member 22 in the axial direction D2. The second inclined surface 44E is inclined to gradually approach the sprocket member 22 in the axial direction D2 with respect to the rotational center axis A1 from a radially inner side to a radially outer side. The second inclined surface 44E guides the outer link plate BC2 of the bicycle chain BC away from the second adjacent tooth 48 in the axial direction D2 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12.

[0129] The second switch facilitating protrusion 44 has a second central axis A5 and protrudes from the gear ring member 22 along the second central axis A5. In this embodiment, the second central axis A5 extends in the axial direction D2. While the second central axis A5 of the second switch facilitating protrusion 44 is parallel to the axial direction D2 in this embodiment, the second central axis A5 may be non-parallel to the axial direction D2. The second switch facilitating protrusion 44 includes a second coupling body 44A, an intermediate portion 44B, and an additional protrusion portion 44C. The second coupling body 44A includes the second inclined surface 44E. In this embodiment, the additional protrusion portion 44C has a ring shape, and the second inclined surface 44E includes a tapered surface arranged around the second central axis A5. As shown in Fig. As can be seen in Figure 14, the first pitch P1 is defined between the first central axis A4 and the second central axis A5.

[0130] As in the Fig. 17, Fig. 18 and Fig. 21, the intermediate part 44B protrudes from the second coupling body 44A along the second center axis A5 toward an opposite side of the ring gear member 22. The additional protrusion part 44C protrudes radially outward from the intermediate part 44B. The additional protrusion part 44C has an annular shape and includes a third inclined surface 44C1 facing the ring gear member 22. The third inclined surface 44C1 is inclined to gradually approach the ring gear member 22 in the axial direction D2 with respect to the rotational center axis A1 from the radially outer side to the radially inner side. In this embodiment, the third inclined surface 44C1 includes a tapered surface arranged around the second center axis A5. The second inclined surface 44E, the third inclined surface 44C1, and the intermediate part 44B define an annular groove 44F.

[0131] The second coupling body 44A includes a second base body 44A1, a second head portion 44A2, and a second connecting portion 44A3. The second base body 44A1 is disposed on the first axial surface S1. The intermediate portion 44B protrudes from the second base body 44A1 along the second center axis A5 toward an opposite side of the sprocket member 22. The second base body 44A1 can be brought into contact with the outer link plate BC2 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The second base body 44A1 includes the second inclined surface 44E. The second head portion 44A2 is disposed on the second axial surface S2. The second connecting part 44A3 connects the second head part 44A2 to the second base body 44A1 and extends through a second mounting hole 22B of the gear ring element 22.The second base body 44A1 has an outer diameter that is larger than an outer diameter of the second connecting part 44A3. The second head part 44A2 has an outer diameter that is larger than the outer diameter of the second connecting part 44A3. The second base body 44A1, the second head part 44A2, and the second connecting part 44A3 constitute a rivet. However, the second switch facilitating projection 44 can be coupled to the gear ring element 22 with other coupling structures.

[0132] As in the Fig. 5 and Fig. As shown in Figure 11, the plurality of sprocket teeth 26 includes a receiving tooth 50 adjacent to the first adjacent tooth 46 without another tooth between the receiving tooth 50 and the first adjacent tooth 46 in the circumferential direction D1 defined about the rotational center axis A1. The receiving tooth 50 is provided on an upstream side of the first adjacent tooth 46 in the rotational direction D11 in which the bicycle sprocket 12 rotates during pedaling.

[0133] As in Fig. 14, the receiving tooth 50 is configured to first engage the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The receiving tooth 50 is provided on an upstream side of the at least one shift facilitation projection 42 and / or 44 in the rotational direction D11 in which the bicycle sprocket 12 rotates during pedaling. In this embodiment, the receiving tooth 50 is provided on the upstream side of the shift facilitation projections 42 and 44 in the rotational direction D11. More specifically, the receiving tooth 50 is provided on the upstream side of the first adjacent tooth 46 in the rotational direction D11 so as to be adjacent to the first adjacent tooth 46 without another tooth between the receiving tooth 50 and the first adjacent tooth 46.However, the receiving tooth 50 may be provided on the upstream side of only one of the switch facilitating projections 42 and 44 in the rotation direction D11.

[0134] As in Fig. As seen in Figure 22, the receiving tooth 50 includes a tooth root 50A and a tooth tip 50B. The tooth root 50A is coupled to the radially outer edge of the ring gear body 24. The tooth root 50A has a first axial center AC1 defined in the axial direction D2, which is parallel to the rotational center axis A1. The tooth tip 50B is provided radially outward from the tooth root 50A with respect to the rotational center axis A1. The tooth tip 50B has a second axial center AC2 defined in the axial direction D2. The second axial center AC2 is provided at an axial position equal to an axial position of the first axial center AC1 in the axial direction D2. In other words, the tooth tip 50B (the second axial center AC2) is not substantially offset from the first axial center AC1 in the axial direction D2. The receiving tooth 50 has an axial width W6 which is smaller than the second chain engagement width W2.The receiving tooth 50 may have an axial width that is less than or equal to the first chain engagement width W1.

[0135] As in the Fig. 5 and Fig. 11, the plurality of sprocket teeth 26 includes a shear tooth 51 adjacent to the second adjacent tooth 48 without another tooth between the shear tooth 51 and the second adjacent tooth 48 in the circumferential direction D1. The shear tooth 51 is provided on a downstream side of the second adjacent tooth 48 in the rotational direction D11. More specifically, the shear tooth 51 is provided on the downstream side of the second adjacent tooth 48 in the rotational direction D11 so as to be adjacent to the second adjacent tooth 48 without another tooth between the shear tooth 51 and the second adjacent tooth 48. The shear tooth 51 is configured to first shear the bicycle chain BC from the bicycle sprocket 12 when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. The ejection tooth 51 is provided on a downstream side of the at least one switch facilitating projection 42 and / or 44 in the direction of rotation D11.In this embodiment, the ejection tooth 51 is provided on the downstream side of the switch facilitating projections 42 and 44 in the rotation direction D11. However, the ejection tooth 51 may be provided on the downstream side of only one of the switch facilitating projections 42 and 44 in the rotation direction D11.

[0136] As in Fig. As shown in Figure 11, the receiving tooth 50 has a radial length L4 that is less than a radial length L5 of the second adjacent tooth 48. However, the radial length L4 of the receiving tooth 50 may be greater than or equal to the radial length L5 of the second adjacent tooth 48. The radial length L4 of the receiving tooth 50 is less than a radial length L6 of the first adjacent tooth 46. However, the radial length L4 of the receiving tooth 50 may be greater than or equal to the radial length L6 of the first adjacent tooth 46. The radial length L6 of the first adjacent tooth 46 is less than the radial length L5 of the second adjacent tooth 48.

[0137] The gear ring element 22 comprises a plurality of tooth bases 52 (see Fig. 11). Each of the plurality of tooth roots 52 is arranged between the first tooth 28 and the second tooth 30 in the circumferential direction D1. The plurality of tooth roots 52 defines a root circle RC. The radial length L4 of the receiving tooth 50 is defined radially from the root circle RC to a radially outermost end of the receiving tooth 50. The radial length L5 of the second adjacent tooth 48 is defined radially from the root circle RC to a radially outermost end of the second adjacent tooth 48. The radial length L6 of the first adjacent tooth 46 is defined radially from the root circle RC to a radially outermost end of the first adjacent tooth 46.

[0138] As in Fig. 14, the gear element 22 comprises side recesses 54 ( Fig. 5) to reduce the interference between the sprocket member 22 and the bicycle chain BC, and to guide the bicycle chain BC toward the sprocket teeth 26 of the bicycle sprocket 12 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The side recesses 54 are provided on the sprocket body 24. The second shift facilitating projection 44 is provided between the side recess 54 and the first shift facilitating projection 42 in the circumferential direction D1.

[0139] An upshift operation of the bicycle chain BC in the bicycle sprocket assembly 10 is described below with reference to the Fig. 14, Fig. 23 and Fig. 24 described.

[0140] As in the Fig. 14 and Fig. 23, the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12 by a front derailleur (not shown) in the upshift operation. This engages the second shift facilitation projection 44 with the outer link plate BC2A of the bicycle chain BC. The opposing pair of link plates BC2A and BC2B are moved upward by the second switch facilitation projection 44 in response to the rotation of the bicycle sprocket assembly 10 in a state where the second switch facilitation projection 44 is engaged with the outer link plate BC2A. At this time, the inner link plate BC1A is guided by the first inclined surface 42E of the first switch facilitation projection 42 to the first adjacent tooth 46 in the axial direction D2.Thus, the opposing pair of inner link plates BC1A and BC1B is moved by the first switch facilitating projection 42 toward the first adjacent tooth 46 in the axial direction D2, causing the first switch facilitating projection 42 to be inserted into the inner link space BC11A of the opposing pair of inner link plates BC1A and BC1B.

[0141] In this state, the outer link plate BC2A is guided by the second inclined surface 44E of the second shift facilitation protrusion 44 to move away from the sprocket member 22 in the axial direction D2. Thus, the opposing pair of outer link plates BC2A and BC2B are further inclined relative to the sprocket member 22. This helps the inner link plate BC1A to be guided by the first switch facilitation protrusion 42 to the first adjacent tooth 46 in the axial direction D2. The opposing pair of outer link plates BC2C and BC2D are initially received by the receiving tooth 50 as the bicycle sprocket assembly 10 continues to rotate about the rotational center axis A1 in the rotational direction D11.The opposing pair of outer link plates BC2C and BC2D are arranged on an upstream side of the switch facilitating projection 44 in the rotation direction D11 so as to be adjacent to the second switch facilitating projection 44 without another outer link plate between the second switch facilitating projection 44 and the opposing pair of outer link plates BC2C and BC2D.

[0142] The first switch facilitating projection 42 is released from the inner link plate BC1A once when the bicycle sprocket assembly 10 continues to rotate about the rotational center axis A1 in the rotational direction D11. As shown in Fig. 24, the first adjacent tooth 46 is then inserted into the inner link space BC11A of the opposing pair of inner link plates BC1A and BC1B in the chain engagement region. This engages the opposing inner link plates BC1A and BC1B with the first adjacent tooth 46.

[0143] A downshift operation of the bicycle chain BC in the bicycle sprocket assembly 10 is described below with reference to the Fig. 25 and Fig. 26 described.

[0144] As in the Fig. 25 and Fig. As can be seen in Figure 26, the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14 by the front derailleur (not shown) during the downshift operation. The pair of inner link plates BC1E and BC1F are ejected from the bicycle sprocket 12 at the ejection tooth 51 during the downshift operation. As shown in Fig. 25, at this time, the outer link plate BC2E is engaged with the second shift facilitating projection 44 in a state where the pair of inner link plates BC1E and BC1F are thrown off the throw-off tooth 51. This adjusts (extends in this embodiment) a chain downshift pitch RT1 ( Fig. 25) of the bicycle chain BC, which is defined from the bicycle sprocket 12 to the smaller sprocket 14, such that the bicycle chain BC engages with a tooth of the smaller sprocket 14 without undesirably running on a tip of the tooth of the smaller sprocket 14, compared to a chain downshift distance RT2 ( Fig. 25) in a case where the bicycle sprocket 12 does not include the second shift facilitating protrusion 44. Accordingly, it is possible to smooth the downshifting operation from the bicycle sprocket 12 to the smaller sprocket 14.

[0145] The bicycle sprocket 12 has the following features. (1) The first shift facilitation protrusion 42 is coupled to the sprocket member 22 to engage with the inner link plate BC1 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The second shift facilitation protrusion 44 is coupled to the sprocket member 22 to engage with the outer link plate BC2 of the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. The first shift facilitation protrusion 42 and the second shift facilitation protrusion 44 facilitate a first shifting operation (e.g., the upshifting operation) in which the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. This improves the shifting performance of the bicycle sprocket 12. (2) The second switch facilitation protrusion 44 is provided on the downstream side of the first switch facilitation protrusion 42 in the rotation direction D11, without another switch facilitation protrusion between the first switch facilitation protrusion 42 and the second switch facilitation protrusion 44 in the rotation direction D11. Accordingly, it is possible to effectively facilitate the first switching operation by using the second switch facilitation protrusion 44 in addition to the first switch facilitation protrusion 42. (3) The first shift facilitation protrusion 42 is spaced apart from the second shift facilitation protrusion 44 by the first pitch P1 in the circumferential direction D1. The first pitch P1 is substantially equal to a chain pitch of the bicycle chain BC. Accordingly, it is possible to more effectively facilitate the first shift operation by using the second shift facilitation protrusion 44 in addition to the first shift facilitation protrusion 42. (4) The first adjacent tooth 46 is closest to the first switch facilitating protrusion 42 among the plurality of ring gear teeth 26. The second adjacent tooth 48 is closest to the second switch facilitating protrusion 44 among the plurality of ring gear teeth 26. Accordingly, it is possible to narrow the area where the first switch facilitating protrusion 42 and the second switch facilitating protrusion 44 are provided in the rotation direction D11. (5) The tooth root 50A of the female tooth 50 has the first axial center AC1 defined in the axial direction D2. The tooth tip 50B of the female tooth 50 has the second axial center AC2 defined in the axial direction D2. The second axial center AC2 is provided at an axial position equal to an axial position of the first axial center AC1 in the axial direction D2. Accordingly, the bicycle chain BC is less likely to land on the tooth tip 50B of the female tooth 50 when the bicycle chain BC is shifted between the bicycle sprocket 12 and the smaller sprocket 14. Thus, it is possible to keep the bicycle chain BC stable when a pedaling force is transmitted from the bicycle sprocket 12 to the bicycle chain BC during pedaling without shifting the bicycle chain BC. (6) The first axial length L1 of the first shift facilitation protrusion 42 is smaller than the second axial length L2 of the second switch facilitation protrusion 44. Accordingly, it is possible to reduce the interference between the first switch facilitation protrusion 42 and the bicycle chain BC during a second shifting operation (e.g., the downshifting operation) in which the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. (7) The first shift facilitating protrusion 42 includes the first coupling body 42A and the protrusion part 42B. The first coupling body 42A is coupled to the sprocket member 22. The protrusion part 42B extends radially outward from the first coupling body 42A with respect to the rotational center axis A1. Thus, the protrusion part 42B can easily catch the bicycle chain BC when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. This facilitates the first shifting operation of the bicycle chain BC. (8) The protrusion portion 42B is spaced apart from the sprocket member 22 in the axial direction D2, which is parallel to the rotational center axis A1. Accordingly, the protrusion portion 42B can hold the inner link plate of the bicycle chain BC between the protrusion portion 42B and the sprocket member 22 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. This can effectively facilitate the first shifting operation of the bicycle chain BC. (9) The maximum axial distance L3 defined between the protrusion portion 42B and the first adjacent tooth 46 in the axial direction D2 is larger than the axial width W5 of the inner link plate BC1. Accordingly, it is possible to reduce the interference between the protrusion portion 42B and the bicycle chain BC during pedaling without switching the bicycle chain BC. This can reduce noise caused by the interference between the protrusion portion 42B and the bicycle chain BC. (10) The first shift relief protrusion 42 is arranged to maintain the clearance of at least one of between the protrusion part 42B and the inner link plate BC1 in the axial direction D2 and between the first adjacent tooth 46 and the inner link plate BC1 in the axial direction D2 during pedaling. Accordingly, it is possible to reduce a resistance force generated by at least one of between the protrusion part 42B and the inner link plate BC1 and between the first adjacent tooth 46 and the inner link plate BC1. This can reduce noise caused by the interference between the protrusion part 42B and the bicycle chain BC. (11) Since the maximum axial clearance L3 is within a range of 0.5 mm to 4.0 mm, it is possible to safely reduce the resistance force. This can effectively reduce noise caused by the interference between the protrusion portion 42B and the bicycle chain BC. (12) Since the maximum axial distance L3 is greater than or equal to 1.0 mm, it is possible to reduce the resistance force more safely. This can more effectively reduce noise caused by the interference between the protrusion part 42B and the bicycle chain BC. (13) Since the maximum axial distance L3 is less than or equal to 3.8 mm, it is possible to reduce the resistance force more safely. This can more effectively reduce noise caused by the interference between the protrusion part 42B and the bicycle chain BC. (14) Since the maximum axial distance L3 is in a range of 1.0 mm to 2.0 mm, it is possible to more safely reduce the resistance force. This can more effectively reduce noise caused by the interference between the protrusion portion 42B and the bicycle chain BC. Furthermore, the smaller maximum axial distance L3 can bring the inner link plate BC1 closer to the sprocket member 22. Thus, it is possible to safely perform the switching of the bicycle chain BC. (15) The first inclined surface 42E of the protrusion portion 42B can guide the bicycle chain BC toward the sprocket member 22 in the axial direction D2 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. This can easily engage the bicycle chain BC with the first shift facilitating protrusion 42 and bring the bicycle chain BC closer to the sprocket member 22. (16) The second inclined surface 44E of the second shift facilitating protrusion 44 can guide the bicycle chain BC in the axial direction D2 away from the sprocket member 22 when the bicycle chain BC is shifted from the smaller sprocket 14 to the bicycle sprocket 12. This can incline the bicycle chain BC to easily engage with the plurality of sprocket teeth 26, effectively facilitating the first shifting operation of the bicycle chain BC. (17) The protrusion portion 42B is arranged to at least partially overlap one of the plurality of sprocket teeth 26 when viewed from the axial direction D2 parallel to the rotational center axis A1. This can increase a radial height of the first shift facilitating protrusion 42. Accordingly, it is possible to effectively bring the bicycle chain BC closer to the sprocket member 22. (18) The second chain engagement width W2 is larger than the inner link gap BC11 and smaller than an outer link gap BC21 defined between an opposing pair of outer link plates BC2 of the bicycle chain BC. Accordingly, it is possible to easily maintain the engagement of the bicycle chain BC with the at least one first tooth 28 and the at least one second tooth 30. (19) Since the at least one first tooth 28 includes the first adjacent tooth 46, it is possible to engage the inner link plate of the bicycle chain BC with the first adjacent tooth 46 during the first shifting operation of the bicycle chain BC. This causes the inner link plate BC to be engaged with the first shift facilitating projection 42 during the first shifting operation. (20) Since the at least one second tooth 30 includes the second adjacent tooth 48, it is possible to engage the outer link plate of the bicycle chain BC with the second adjacent tooth 48 during the first shifting operation of the bicycle chain BC. This causes the outer link plate of the bicycle chain BC to be engaged with the second shift facilitating projection 44 during the first shifting operation. (21) The receiving tooth 50 has an axial width W5 that is smaller than the second chain engagement width W2. Accordingly, it is possible to smoothly receive the bicycle chain BC on the receiving tooth 50. This facilitates the first shifting operation of the bicycle chain BC. (22) The receiving tooth 50 has the radial length L4, which is smaller than the radial length L5 of the second adjacent tooth 48. Accordingly, it is possible to smoothly receive the bicycle chain BC on the receiving tooth 50. This facilitates the first shifting operation of the bicycle chain BC. (23) The second shift facilitating protrusion 44 is coupled to the sprocket member 22 to engage with the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. Accordingly, it is possible to facilitate the second shifting operation (e.g., the downshifting operation) in which the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. (24) The first shifting facilitation protrusion 42 is arranged not to be interposed between an opposing pair of link plates of the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. Accordingly, it is possible to smoothly shift the bicycle chain BC from the bicycle sprocket 12 to the smaller sprocket 14 independently of the first shifting facilitation protrusion 42. Second embodiment

[0146] A bicycle sprocket assembly 210 comprising a bicycle sprocket 212 according to a second embodiment is described below with reference to Fig. 27 to 33. The bicycle sprocket 212 has the same structure and / or configuration as that of the bicycle sprocket 12, with the exception of the second shift facilitating projection 44. Thus, elements having substantially the same function as those in the first embodiment are numbered the same here and will not be described and / or illustrated in detail again for the sake of brevity.

[0147] As in the Fig. As seen in FIGS. 27 to 33, the bicycle sprocket 212 includes the sprocket member 22, the first switch facilitation protrusion 42, and a second switch facilitation protrusion 244. In this embodiment, the bicycle sprocket 212 includes the plurality of first switch facilitation protrusions 42 and a plurality of second switch facilitation protrusions 244. The second switch facilitation protrusion 244 has substantially the same structure as that of the second switch facilitation protrusion 44 of the first embodiment. The second switch facilitation protrusion 244 has a different shape from the second switch facilitation protrusion 44. The intermediate portion 44B and the additional protrusion portion 44C are omitted from the second switch facilitation protrusion 244.

[0148] With the bicycle sprocket 212, it is possible to achieve substantially the same effects as those of the bicycle sprocket 12 of the first embodiment. Third embodiment

[0149] A bicycle sprocket assembly 310 comprising a bicycle sprocket 312 according to a third embodiment is described below with reference to Fig. 34 and Fig. 35. The bicycle sprocket 312 has the same structure and / or configuration as that of the bicycle sprocket 12, with the exception of the receiving tooth 50. Thus, elements that have substantially the same function as those in the above embodiments are numbered the same here and will not be described and / or illustrated in detail again for the sake of brevity.

[0150] As in Fig. 34, the bicycle sprocket 312 includes a sprocket member 322, the first shift facilitation protrusion 42, and the second shift facilitation protrusion 44. The sprocket member 322 has substantially the same structure as that of the sprocket member 22 of the first embodiment. In the sprocket member 322, the plurality of sprocket teeth 26 includes a receiving tooth 350 adjacent to the first adjacent tooth 46 without another tooth between the receiving tooth 350 and the first adjacent tooth 46 in the circumferential direction D1. The receiving tooth 350 is provided on an upstream side of the first adjacent tooth 46 in the rotational direction D11. The receiving tooth 350 has substantially the same structure as that of the receiving tooth 50 of the first embodiment.

[0151] As in Fig. As shown in Figure 35, the receiving tooth 350 includes the tooth root 50A and a tooth tip 350B. The tooth tip 350B is positioned radially outward from the tooth root 50A with respect to the rotational center axis A1. The tooth tip 350B has a second axial center AC32 defined in the axial direction D2. The second axial center AC32 is offset from the first axial center AC1 in the axial direction D2. In this embodiment, the tooth tip 350B is a radially outermost surface of the receiving tooth 350.

[0152] The second axial center AC32 is closer in the axial direction D2 than the first axial center AC1 to the at least one shift facilitation protrusion 42 and / or 44. In this embodiment, the second axial center AC32 is closer in the axial direction D2 than the first axial center AC1 to the first shift facilitation protrusion 42. More specifically, the second axial center AC32 is closer in the axial direction D2 than the first axial center AC1 to the protrusion portion 42B of the first shift facilitation protrusion 42. If the second axial center AC32 is arranged closer than the first axial center AC1 to one of the shift facilitation protrusions 42 and 44, it is possible to omit one of the shift facilitation protrusions 42 and 44 from the bicycle sprocket 312 for the upshift operation. Preferably, in such a configuration, the first shift facilitation protrusion 42 can be omitted.However, it is preferred that the bicycle sprocket 312 includes both of the first and second shift facilitating protrusions 42 and 44 for better upshift operation.

[0153] With the bicycle sprocket 312, it is possible to achieve substantially the same effects as those of the bicycle sprocket 12 of the first embodiment.

[0154] Furthermore, the second axial center AC32 is offset from the first axial center AC1 in the axial direction D2. Accordingly, it is possible to securely receive the bicycle chain BC with the receiving tooth 350, which improves the first shifting operation (e.g., the upshifting operation).

[0155] The second axial center AC32 is closer in the axial direction D2 than the first axial center AC1 to the at least one shift facilitating projection 42 and / or 44. Accordingly, it is possible to more securely receive the bicycle chain BC with the receiving tooth 350, which improves the first shifting operation.

[0156] In this embodiment, the second axial center AC32 is closer in the axial direction D2 than the first axial center AC1 to the at least one switch facilitating projection 42 and / or 44. However, the second axial center AC32 may be farther in the axial direction D2 than the first axial center AC1 from the at least one switch facilitating projection 42 and / or 44, if needed and / or desired. Fourth embodiment

[0157] A bicycle sprocket assembly 410 comprising a bicycle sprocket 412 according to a fourth embodiment is described below with reference to Fig. 36 to 38. The bicycle sprocket 412 has the same structure and / or configuration as that of the bicycle sprocket 12, except for a third shift facilitating protrusion. Thus, elements that have substantially the same function as those in the above embodiments are numbered the same here and, for the sake of brevity, will not be described and / or illustrated in detail again.

[0158] As in the Fig. 36 to 38, the bicycle sprocket 412 includes the sprocket member 22, the first shift facilitation protrusion 42, the second shift facilitation protrusion 44, and a third shift facilitation protrusion 445. Unlike the first embodiment, the second shift facilitation protrusion 44 does not engage the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14. In this embodiment, the third shift facilitation protrusion 445 is coupled to the sprocket member 22 to engage the bicycle chain BC when the bicycle chain BC is shifted from the bicycle sprocket 12 to the smaller sprocket 14.

[0159] As in Fig. 37, the plurality of ring gear teeth 26 includes a third adjacent tooth 447. The at least one second tooth 30 includes the third adjacent tooth 447 that is closest to the third switch facilitating projection 445 among the plurality of ring gear teeth 26. In the embodiment shown, the shear tooth 51 is disposed between the first adjacent tooth 46 and the third adjacent tooth 447 in the circumferential direction D1. The shear tooth 51 is disposed between the receiving tooth 50 and the third adjacent tooth 447 in the circumferential direction D1. The third switch facilitating projection 445 is provided on an upstream side of the first switch facilitating projection 42 in the rotational direction D11. The third adjacent tooth 447 is provided on an upstream side of the shedding tooth 51 in the rotation direction D11 so as to be adjacent to the shedding tooth 51 without another tooth between the third adjacent tooth 447 and the shedding tooth 51.The shedding tooth 51 is provided between the first adjacent tooth 46 and the third switch facilitating projection 445 in the circumferential direction D1 (in the rotational direction D11).

[0160] As in Fig. 38, the third switch facilitating projection 445 has a third axial length L7 defined by the gear ring member 22 in the axial direction D2, which is parallel to the rotational center axis A1. The third axial length L7 is smaller than the first axial length L1 and the second axial length L2. In this embodiment, the third axial length L7 is from the first axial end 28A ( Fig. 19) of the first tooth 28 (the first adjacent tooth 46) in the axial direction D2.

[0161] The third switch facilitation protrusion 445 has a third central axis A7 extending in the axial direction D2. While the third central axis A7 of the third switch facilitation protrusion 445 is parallel to the axial direction D2 in this embodiment, the third central axis A7 may be non-parallel to the axial direction D2. The third switch facilitation protrusion 445 includes a third base body 445A, a third head portion 445B, and a third connecting portion 445C. The third base body 445A is disposed on the first axial surface S1. The third base body 445A can be brought into contact with the outer link plate BC2 of the bicycle chain BC. The third head portion 445B is disposed on the second axial surface S2. The third connecting part 445C connects the third head part 445B to the third base body 445A and extends through a third mounting hole 22C of the gear ring element 22.The third base body 445A has an outer diameter that is larger than an outer diameter of the third connecting part 445C. The third head part 445B has an outer diameter that is larger than the outer diameter of the third connecting part 445C. The third base body 445A, the third head part 445B, and the third connecting part 445C constitute a rivet. However, the third switch facilitating projection 445 can be coupled to the gear ring member 22 with other coupling structures.

[0162] With the bicycle sprocket 412, it is possible to achieve substantially the same effects as those of the bicycle sprocket 12 of the first embodiment.

[0163] In the present application, it is possible to at least partially combine the structures described in the above embodiments. For example, in a bicycle sprocket 512 of a bicycle sprocket assembly 510 described in Fig.39, the third switch facilitating projection 445 may be applied to the bicycle sprocket 312 of the third embodiment.

[0164] As used herein, the term "comprising" and its derivatives are intended to be open-ended terms that indicate the presence of the specified features, elements, components, groups, numbers, and / or steps, but do not exclude the presence of other, unspecified features, elements, components, groups, numbers, and / or steps. This concept also applies to words of similar meaning, for example, the terms "comprise," "include," and their derivatives.

[0165] The terms “component”, “section”, “portion”, “part”, “element”, “body” and “structure”, when used in the singular, can have the dual meaning of a single part or a plurality of parts.

[0166] The atomic numbers, such as "first" and "second," used in this application are merely designations and do not have any other meanings, such as a specific order, etc. Furthermore, the term "first element" itself does not imply the existence of a "second element," nor does the term "second element" itself imply the existence of a "first element."

[0167] The term "pair of" as used herein may include the formation in which the pair of elements have different shapes or structures from each other, in addition to the formation in which the pair of elements have the same shapes or structures.

[0168] Finally, terms of extent, such as “substantially,” “approximately,” and “approximately,” as used herein, mean a reasonable degree of deviation from the term being qualified, such that the final result is not significantly changed.

Claims

[1] Bicycle sprocket (12, 212, 312, 412, 512), comprising: a gear ring element (22, 322) comprising a central axis of rotation (A1), a ring gear body (24) comprising a radially outer edge arranged around the rotational center axis (A1), and a plurality of ring gear teeth (26) arranged on the radially outer edge; a first shift facilitating projection (42) coupled to the sprocket member (22, 322) for engaging an inner link plate (BC1) of a bicycle chain (BC) when the bicycle chain (BC) is shifted from a smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512); and a second shift facilitating projection (42, 44, 244) coupled to the sprocket member (22, 322) for engaging an outer link plate (BC2) of the bicycle chain (BC) when the bicycle chain (BC) is shifted from the smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512). [2] The bicycle sprocket (12, 212, 312, 412, 512) according to claim 1, wherein the second switch facilitating projection (44, 244) is provided on a downstream side of the first switch facilitating projection (42) in a rotational direction in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, without another switch facilitating projection (42, 44) between the first switch facilitating projection (42) and the second switch facilitating projection (42, 44, 244) in the rotational direction. [3] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 1 or 2, wherein the first shift facilitating projection (42) is spaced from the second shift facilitating projection (42, 44, 244) by a first pitch in a circumferential direction (D1) defined about the rotational center axis (A1), and the first pitch is substantially equal to a chain pitch of the bicycle chain (BC). [4] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 3, wherein the plurality of toothed ring teeth (26) comprises a first adjacent tooth (46), and a second adjacent tooth (48) adjacent to the first adjacent tooth (46) without another tooth in a circumferential direction (D1) defined about the rotational center axis (A1), the first adjacent tooth (46) of the plurality of gear teeth (26) is closest to the first switch relief projection (42), and the second adjacent tooth (48) of the plurality of gear teeth (26) is closest to the second switch relief projection (42, 44, 244). [5] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 4, wherein the plurality of gear teeth (26) comprises a receiving tooth (50, 350) adjacent to the first adjacent tooth (46) without another tooth between the receiving tooth (50, 350) and the first adjacent tooth (46) in the circumferential direction (D1), the receiving tooth (50, 350) is provided on an upstream side of the first adjacent tooth (46) in a direction of rotation in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, the receiving tooth (50, 350) comprises a tooth root (50A) coupled to the radially outer edge of the ring gear body (24), the tooth root (50A) having a first axial center (AC1) defined in an axial direction (D2) parallel to the rotational center axis (A1), and a tooth tip (350B) provided radially outward from the tooth root (50A) with respect to the rotational center axis (A1), the tooth tip (350B) having a second axial center (AC2) defined in the axial direction (D2), and the second axial center (AC2) is provided at an axial position which is equal to an axial position of the first axial center (AC1) in the axial direction (D2). [6] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 4 to 5, wherein the plurality of gear teeth (26) comprises a receiving tooth (50, 350) adjacent to the first adjacent tooth (46) without another tooth between the receiving tooth (50, 350) and the first adjacent tooth (46) in the circumferential direction (D1), the receiving tooth (50, 350) is provided on an upstream side of the first adjacent tooth (46) in a direction of rotation in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, the receiving tooth (50, 350) comprises a tooth root (50A) coupled to the radially outer edge of the ring gear body (24), the tooth root (50A) having a first axial center (AC1) defined in an axial direction (D2) parallel to the rotational center axis (A1), and a tooth tip (350B) provided radially outward from the tooth root (50A) with respect to the rotational center axis (A1), the tooth tip (350B) having a second axial center (AC2) defined in the axial direction (D2), and the second axial center (AC2) is offset from the first axial center (AC1) in the axial direction (D2). [7] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 5 to 6, wherein the second axial center (AC2) is closer in the axial direction (D2) than the first axial center (AC1) to the first shift facilitating projection (42). [8] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 7, wherein the first switch relief projection (42) has a first axial length defined by the gear ring element (22, 322) in an axial direction (D2) parallel to the rotational center axis (A1), the second switch relief projection (44, 244) has a second axial length defined by the gear ring element (22, 322) in the axial direction (D2), and the first axial length is smaller than the second axial length. [9] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 8, wherein the first switch relief projection (42) comprises a first coupling body (42A) coupled to the gear ring element (22, 322), and a projection part (42B) extending radially outward from the first coupling body (42A) with respect to the rotational center axis (A1). [10] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 9, wherein the projection part (42B) is spaced from the sprocket element (22, 322) in an axial direction (D2) parallel to the rotational center axis (A1). [11] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 9 to 10, wherein the plurality of gear teeth (26) includes a first adjacent tooth (46) that is closest to the first switch relief projection (42) of the plurality of gear teeth (26), and a maximum axial distance (L3) defined between the projection part (42B) and the first adjacent tooth (46) in the axial direction (D2) is greater than an axial width of the inner link plate (BC1). [12] The bicycle sprocket (12, 212, 312, 412, 512) according to claim 11, wherein the first shift facilitating projection (42) is arranged to maintain a clearance of at least one of between the projection part (42B) and the inner link plate (BC1) in the axial direction (D2) and between the first adjacent tooth (46) and the inner link plate (BC1) in the axial direction (D2) during pedaling. [13] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 11 to 12, wherein the maximum axial distance (L3) is in a range of 0.5 mm to 4.0 mm. [14] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 11 to 13, wherein the maximum axial distance (L3) is greater than or equal to 1.0 mm. [15] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 11 to 14, wherein the maximum axial distance (L3) is less than or equal to 3.8 mm. [16] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 11 to 15, wherein the maximum axial distance (L3) is in a range of 1.0 mm to 2.0 mm. [17] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 9 to 16, wherein the projection part (42B) comprises a radially inner end (42C) coupled to the first coupling body (42A), a radially outer end (42D) provided radially outward from the radially inner end (42C) with respect to the rotational center axis (A1), and a first inclined surface (42E) facing the gear ring member (22, 322) in the axial direction (D2), the first inclined surface (42E) being inclined so as to gradually approach the gear ring member (22, 322) in the axial direction (D2) from the radially outer end (42D) to the radially inner end (42C). [18] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 17, wherein the second switch facilitating projection (44, 244) comprises a second inclined surface (44E) facing an opposite side of the gear ring element (22) in the axial direction (D2), and the second inclined surface (44E) is inclined so as to gradually approach the ring gear member (22, 322) in the axial direction (D2) with respect to the rotational center axis (A1) from a radially inner side to a radially outer side. [19] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 9 to 18, wherein the projection part (42B) is arranged to at least partially overlap with one of the plurality of sprocket teeth (26) when viewed from an axial direction (D2) parallel to the rotational center axis (A1). [20] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 19, wherein the plurality of toothed ring teeth (26) comprises at least one first tooth (28) having a first chain engagement width (W1), and at least one second tooth (30) having a second chain engagement width (W2), the first chain engagement width (W1) is smaller than an inner link gap (BC11) defined between an opposing pair of inner link plates (BC1) of the bicycle chain (BC), and the second chain engagement width (W2) is larger than the inner link gap (BC11) and smaller than an outer link gap (BC21) defined between an opposing pair of outer link plates of the bicycle chain (BC). [21] The bicycle sprocket (12, 212, 312, 412, 512) of claim 20, wherein the at least one first tooth (28) comprises a first adjacent tooth (46) that is closest to the first shift facilitating projection (42) of the plurality of sprocket teeth (26). [22] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 20 to 21, wherein the at least one second tooth (30) comprises a second adjacent tooth (48) which is closest to the second shift facilitating projection (42, 44, 244) of the plurality of sprocket teeth (26). [23] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 4 to 22, wherein the plurality of gear teeth (26) comprises a receiving tooth (50, 350) adjacent to the first adjacent tooth (46) without another tooth between the receiving tooth (50, 350) and the first adjacent tooth (46) in a circumferential direction (D1) defined about the rotational center axis (A1), the receiving tooth (50, 350) is provided on an upstream side of the first adjacent tooth (46) in a direction of rotation in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, and the receiving tooth (50, 350) has an axial width which is smaller than the second chain engagement width (W2). [24] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 22 to 23, wherein the plurality of gear teeth (26) comprises a receiving tooth (50, 350) adjacent to the first adjacent tooth (46) without another tooth between the receiving tooth (50, 350) and the first adjacent tooth (46) in a circumferential direction (D1) defined about the rotational center axis (A1), the receiving tooth (50, 350) is provided on an upstream side of the first adjacent tooth (46) in a direction of rotation in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, and the receiving tooth (50, 350) has a radial length which is smaller than a radial length of the second adjacent tooth (48). [25] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 24, wherein the second shift facilitating projection (44, 244) is coupled to the sprocket member (22, 322) to engage with the bicycle chain (BC) when the bicycle chain (BC) is shifted from the bicycle sprocket (12, 212, 312, 412, 512) to the smaller sprocket (14). [26] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 1 to 25, wherein the first shift facilitating projection (42) is arranged not to be inserted between an opposing pair of link plates of the bicycle chain (BC) when the bicycle chain (BC) is shifted from the bicycle sprocket (12, 212, 312, 412, 512) to the smaller sprocket (14). [27] Bicycle sprocket (12, 212, 312, 412, 512), comprising: a gear ring element (22, 322) comprising a central axis of rotation (A1), a ring gear body (24) comprising a radially outer edge arranged around the rotational center axis (A1), and a plurality of gear teeth (26) arranged on the radially outer edge; and a first shift facilitating projection (42) coupled to the sprocket member (22, 322) and configured to engage between an opposing pair of inner connecting plates (BC1) of a bicycle chain (BC) when the bicycle chain (BC) is shifted from a smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512), wherein the first shift facilitating projection (42) comprises a first coupling body (42A) coupled to the gear ring element (22, 322), and a projection part (42B) extending radially outward from the first coupling body (42A) with respect to the rotational center axis; wherein the plurality of gear teeth (26) comprises a first adjacent tooth (46) which is closest to the first switch relief projection (42) of the plurality of gear teeth (26), and a receiving tooth (50, 350) adjacent to the first adjacent tooth (46) without another tooth between the receiving tooth (50, 350) and the first adjacent tooth (46) in a circumferential direction (D1) defined about the rotational center axis (A1), wherein the receiving tooth (50, 350) is provided on an upstream side of the first adjacent tooth (46) in a rotational direction in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling; and a maximum axial distance (L3) defined between the protrusion portion (42B) and the first adjacent tooth (46) in an axial direction (D2) parallel to the rotational center axis (A1) is in a range of 0.5 mm to 4.0 mm. [28] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 27, wherein the maximum axial distance (L3) is greater than or equal to 1.0 mm. [29] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 27 or 28, wherein the maximum axial distance (L3) is less than or equal to 3.8 mm. [30] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 29, wherein the maximum axial distance (L3) is in a range of 1.0 mm to 2.0 mm. [31] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 30, wherein the receiving tooth (50, 350) comprises a tooth root (50A) coupled to the radially outer edge of the ring gear body (24), the tooth root (50A) having a first axial center (AC1) defined in the axial direction (D2), and a tooth tip (350B) provided radially outward from the tooth root (50A) with respect to the rotational center axis (A1), the tooth tip (350B) having a second axial center (AC2) defined in the axial direction (D2), and the second axial center (AC2) is provided at an axial position which is equal to an axial position of the first axial center (AC1) in the axial direction (D2). [32] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 31, wherein the receiving tooth (50, 350) comprises a tooth root (50A) coupled to the radially outer edge of the ring gear body (24), the tooth root (50A) having a first axial center (AC1) defined in the axial direction (D2), and a tooth tip (350B) provided radially outward from the tooth root (50A) with respect to the rotational center axis (A1), the tooth tip (350B) having a second axial center (AC2) defined in the axial direction (D2), and the second axial center (AC2) is offset from the first axial center (AC1) in the axial direction (D2). [33] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 32, wherein the second axial center (AC2) is closer in the axial direction (D2) than the first axial center (AC1) to the first shift facilitating projection (42). [34] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 33, wherein the first shift facilitating projection (42) is arranged to maintain a clearance of at least one of between the projection part (42B) and an inner link plate (BC1) of the bicycle chain (BC) in the axial direction (D2) and between the first adjacent tooth (46) and the inner link plate (BC1) in the axial direction (D2) during pedaling. [35] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 34, wherein the projection part (42B) comprises a radially inner end coupled to the first coupling body (42A), a radially outer end provided radially outward from the radially inner end with respect to the rotational center axis (A1), and a first inclined surface facing the gear ring member (22, 322) in the axial direction (D2), the first inclined surface being inclined so as to approach the gear ring member (22, 322) in the axial direction (D2) from the radially outer end to the radially inner end. [36] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 35, further comprising: a second switch facilitating projection (42, 44, 244) coupled to the gear ring member (22, 322), the second switch facilitating projection (44, 244) comprising a second inclined surface (44E) facing an opposite side of the gear ring member (22) in the axial direction (D2), and the second inclined surface (44E) is inclined so as to gradually approach the ring gear member (22, 322) in the axial direction (D2) with respect to the rotational center axis (A1) from a radially inner side to a radially outer side. [37] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 36, wherein the projection part (42B) is arranged so as to at least partially overlap with one of the plurality of sprocket teeth (26) as viewed from the axial direction (D2). [38] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 37, wherein the plurality of toothed ring teeth (26) comprises at least one first tooth (28) having a first chain engagement width (W1), and at least one second tooth (30) having a second chain engagement width (W2), the first chain engagement width (W1) is smaller than an inner link gap (BC11) defined between an opposing pair of inner link plates (BC1) of the bicycle chain (BC), and the second chain engagement width (W2) is larger than the inner link gap (BC11) and smaller than an outer link gap (BC21) defined between an opposing pair of outer link plates of the bicycle chain (BC). [39] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 4 to 38, wherein the at least one first tooth (28) comprises the first adjacent tooth (46) that is closest to the first shift facilitating projection (42) of the plurality of sprocket teeth (26). [40] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 20 to 39, further comprising: a second switch relief projection (42, 44, 244) coupled to the gear ring element (22, 322), wherein the at least one second tooth (30) comprises a second adjacent tooth (48) which is closest to the second switch facilitating projection (42, 44, 244) of the plurality of gear teeth (26). [41] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 40, wherein the receiving tooth (50, 350) has an axial width which is smaller than the second chain engagement width (W2). [42] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 41, wherein the receiving tooth (50, 350) has a radial length which is smaller than a radial length of the second adjacent tooth (48). [43] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 27 to 42, wherein the first shift facilitating projection (42) is arranged not to be inserted between the opposing pair of inner link plates of the bicycle chain (BC) when the bicycle chain (BC) is shifted from the bicycle sprocket (12, 212, 312, 412, 512) to the smaller sprocket (14). [44] Bicycle sprocket (12, 212, 312, 412, 512), comprising: a gear ring element (22, 322) comprising a central axis of rotation (A1), a ring gear body (24) comprising a radially outer edge arranged around the rotational center axis (A1), and a plurality of gear teeth (26) arranged on the radially outer edge; and at least one shift facilitating projection (42, 44) coupled to the sprocket element (22, 322) to engage with a connecting link plate of a bicycle chain (BC) when the bicycle chain (BC) is shifted from a smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512), wherein the plurality of gear teeth (26) comprises at least one first tooth (28) having a first chain engagement width (W1), and at least one second tooth (30) having a second chain engagement width (W2), wherein the first chain engagement width (W1) is smaller than an inner link gap (BC11) defined between an opposing pair of inner link plates (BC1) of the bicycle chain (BC), and the second chain engagement width (W2) is larger than the inner link gap (BC11) and smaller than an outer link gap (BC21) defined between an opposing pair of outer link plates of the bicycle chain (BC), the plurality of sprocket teeth (26) comprises a receiving tooth (50, 350) which is designed to first engage with the bicycle chain (BC) when the bicycle chain (BC) is shifted from the smaller sprocket (14) to the bicycle sprocket (12, 212, 312, 412, 512), wherein the receiving tooth (50, 350) is provided on an upstream side of the at least one shift facilitating projection (42, 44) in a rotational direction in which the bicycle sprocket (12, 212, 312, 412, 512) rotates during pedaling, wherein the receiving tooth (50, 350) comprises a tooth root (50A) coupled to the radially outer edge of the ring gear body (24), the tooth root (50A) having a first axial center (AC1) defined in an axial direction (D2) parallel to the rotational center axis (A1), and a tooth tip (350B) provided radially outward from the tooth root (50A) with respect to the rotational center axis (A1), the tooth tip (350B) having a second axial center (AC2) defined in the axial direction (D2), and wherein the second axial center (AC2) is offset from the first axial center (AC1) in the axial direction (D2). [45] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 44, wherein the second axial center (AC2) is closer in the axial direction (D2) than the first axial center (AC1) to the at least one shift facilitating projection (42, 44). [46] Bicycle sprocket (12, 212, 312, 412, 512) according to claim 44 or 45, wherein the second axial center (AC2) is further away from the at least one shift facilitating projection (42, 44) in the axial direction (D2) than the first axial center (AC1). [47] Bicycle sprocket (12, 212, 312, 412, 512) according to one of claims 44 to 46, wherein the receiving tooth (50, 350) has a radial length which is smaller than a radial length of the at least one second tooth (30).

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