A bicycle sprocket comprises sprocket teeth. The sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of a bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width which is smaller than the second distance. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.

A bicycle sprocket comprises sprocket teeth. The sprocket teeth include at least one first tooth and at least one second tooth. The at least one first tooth has a first radial-tooth height. The at least one first tooth has a first chain-engaging axial width which is smaller than a first distance defined between opposed outer link plates of a bicycle chain and which is larger than a second distance defined between opposed inner link plates of the bicycle chain. The first radial-tooth height is greater than the first chain-engaging axial width. The at least one second tooth has a second radial-tooth height. The at least one second tooth has a second chain-engaging axial width which is smaller than the second distance. The second radial-tooth height is greater than the second chain-engaging axial width. The first radial-tooth height is greater than the second radial-tooth height.

A connecting device for a chainring of a bicycle is disclosed, including a connecting disc, a shaft, and a crank. The connecting disc is adapted to be engaged with a chainring, and has an axial bore, a bulging portion bulging from a central portion of the connecting disc, and a surrounding portion, which is flat, and surrounds an outer periphery of the bulging portion. The shaft passes through the axial bore to be fixedly engaged with the connecting disc. The shaft has a connecting end. The crank has a connecting end engaged with the connecting end of the shaft, and a bearing end adapted to bear an external force to make the crank rotate around the shaft. Whereby, the amount of materials used to make the connecting device is decreased. At the same time, the manufacturing cost, the size, and the weight of the connecting device are all reduced.

A connecting device for a chainring of a bicycle is disclosed, including a connecting disc, a shaft, and a crank. The connecting disc is adapted to be engaged with a chainring, and has an axial bore, a bulging portion bulging from a central portion of the connecting disc, and a surrounding portion, which is flat, and surrounds an outer periphery of the bulging portion. The shaft passes through the axial bore to be fixedly engaged with the connecting disc. The shaft has a connecting end. The crank has a connecting end engaged with the connecting end of the shaft, and a bearing end adapted to bear an external force to make the crank rotate around the shaft. Whereby, the amount of materials used to make the connecting device is decreased. At the same time, the manufacturing cost, the size, and the weight of the connecting device are all reduced.

A rotatable assembly, such as a crankshaft or camshaft assembly, includes a first rotatable component and a second rotatable component coupled to the first rotatable component. The first rotatable component includes a first body and defines a plurality of recesses extending into the first body. The second rotatable component includes a second body and defines a plurality of protrusions extending from the second body. The protrusions are disposed inside the respective recesses to allow the second rotatable component to rotate in unison with the first rotatable component.

A rotatable assembly, such as a crankshaft or camshaft assembly, includes a first rotatable component and a second rotatable component coupled to the first rotatable component. The first rotatable component includes a first body and defines a plurality of recesses extending into the first body. The second rotatable component includes a second body and defines a plurality of protrusions extending from the second body. The protrusions are disposed inside the respective recesses to allow the second rotatable component to rotate in unison with the first rotatable component.

A bicycle sprocket includes a sprocket body, and a plurality of sprocket teeth. At least one of the sprocket teeth includes a first layered member, a second layered member and a third layered member. The first layered member has a first axial surface and a second axial surface. The second layered member is attached to the first axial surface such that the first and second layered members overlap each other in an axial direction as viewed parallel to a rotational axis of the sprocket body. The third layered member is attached to the second axial surface such that the first and third layered members overlap each other in the axial direction as viewed parallel to the rotational axis of the sprocket body. The first layered member has a specific gravity that is less than those of the second layered member and the third layered member.

A transmission mechanism has a set of two composite sprockets, each having pinion sprockets (210) supported movably in a radial direction with respect to a rotation shaft 1 that inputs or outputs power and a movement mechanism radially moving the pinion sprockets (210) in synchronization with each other while maintaining equidistance of the pinion sprocket (210) from a shaft center (C.sub.1) of the rotation shaft 1, and a chain wound around the two composite sprockets. Transmission ratio is changed by changing a circumcircle radius that is a radius of a circle encircling and circumscribing all the pinion sprockets (210). The pinion sprocket (210) is formed into a sector gear shape having a teeth portion (212) that is arranged along a circumference of a minimum radius circumcircle (A.sub.1) and meshes with the chain. With this configuration, torque can surely be transmitted.

Transmission mechanism has set of two composite sprockets (5, 5), each having pinion sprockets (20) supported movably in radial direction with respect to rotation shaft (1) inputting or outputting power and movement mechanism radially moving pinion sprockets (20) in synchronization with each other while maintaining equidistance of pinion sprocket (20) from shaft center (C.sub.1) of rotation shaft (1), and chain (6) wound around two composite sprockets. Transmission ratio is changed by changing circumcircle radius that is radius of circle encircling and circumscribing all the pinion sprockets (20). Each guide rod (29) has first guide rod (291) guiding chain (6) all the time regardless of circumcircle radius size, and second guide rod (292) guiding chain (6) at least when circumcircle radius is a maximum and positioned at radial direction inner side with respect to first guide rod (291) when circumcircle radius is a minimum. With this, ratio coverage can be expanded.

Provided is a zipper chain. The zipper chain includes a plurality of chain portions arranged to face each other and engaged with each other at one point while making linear movements. Each chain portion includes a plurality of upper plates connected to each other; a plurality of lower plates arranged to respectively face the upper plates, respectively spaced apart from the upper plates, and connected to each other; a plurality of connecting portions each connecting one of the upper plates to a corresponding one of the lower plates and connecting adjacent upper plates among the plurality of upper plates or adjacent lower plates among the plurality of lower plates; and a plurality of protrusions respectively protruding from the plurality of connecting portions.