A bicycle sprocket wheel unit includes multiple section units connected to each other. Each section unit has teeth formed on the outer periphery thereof. Each section unit has at least one fixing device that is connected to a mounting unit. The mounting unit is made by way of pressing to form an integral ring plate which includes a hub connection hole defined in the center thereof. A first disk, a second disk and a third disk are connected to the mounting unit and share the center of the hub connection hole. A first sprocket wheel and a second sprocket wheel are respectively located on two sides of the third disk. The second disk is connected to a third sprocket wheel and a fourth sprocket wheel. The third disk is riveted to the first and second sprocket wheels along the whole face thereof to reinforce lateral strength of the sprocket wheels.

A bicycle sprocket wheel unit includes multiple section units connected to each other. Each section unit has teeth formed on the outer periphery thereof. Each section unit has at least one fixing device that is connected to a mounting unit. The mounting unit is made by way of pressing to form an integral ring plate which includes a hub connection hole defined in the center thereof. A first disk, a second disk and a third disk are connected to the mounting unit and share the center of the hub connection hole. A first sprocket wheel and a second sprocket wheel are respectively located on two sides of the third disk. The second disk is connected to a third sprocket wheel and a fourth sprocket wheel. The third disk is riveted to the first and second sprocket wheels along the whole face thereof to reinforce lateral strength of the sprocket wheels.

A bicycle having a rear wheel including an axle, a hub shell, a torque element including a torque output portion and a torque input portion, and a rear cog coupled to the torque input portion. The torque output portion is a first radial distance from the torque input portion. The position sensor measures a rotational position of the torque input portion relative to the torque output portion. In one embodiment, the position sensor includes a displacement indicator (e.g., a radial tab mounted to the torque output portion) and a displacement sensor (e.g., an inductive sensor mounted to the torque input portion). The inductive sensor preferably has two sensing coils positioned on each side of the displacement indicator. The hub assembly can further comprise a wireless transmitter adapted to transmit data from the position sensor. The hub shell preferably includes a window that facilitates data transmission from the wireless transmitter.

A bicycle sprocket comprises a sprocket body and a plurality of chain-driving teeth. The plurality of chain-driving teeth comprises a first tooth and a second tooth. The first tooth has a first radial length radially defined from a reference line to a first radially outermost end. The second tooth has a second radial length radially defined from the reference line to a second radially outermost end. The second radial length is in a range of 1.5 mm to 2.9 mm. A shortest distance is defined between the downstream circumferential surface and a first intersection point of the circumferential center plane and an additional reference line. The shortest distance is equal to or larger than 2.0 mm. The additional reference line is defined at a reference position radially outward spaced apart from the reference line by 1.5 mm.

A bicycle sprocket comprises a sprocket body and a plurality of chain-driving teeth. The plurality of chain-driving teeth comprises a first tooth and a second tooth. The first tooth has a first radial length radially defined from a reference line to a first radially outermost end. The second tooth has a second radial length radially defined from the reference line to a second radially outermost end. The second radial length is in a range of 1.5 mm to 2.9 mm. A shortest distance is defined between the downstream circumferential surface and a first intersection point of the circumferential center plane and an additional reference line. The shortest distance is equal to or larger than 2.0 mm. The additional reference line is defined at a reference position radially outward spaced apart from the reference line by 1.5 mm.

A first sprocket includes a first opening having a first diameter smaller than a radially outer diameter of a sprocket support portion of a bicycle rear hub assembly. A lock member includes a main body, a male thread portion, and a radial projection. The main body has a first axial end configured to pass through the first opening and a second axial end opposite to the first axial end in an axial direction. The male thread portion is provided to the first axial end and configured to engage with a female thread portion of the bicycle rear hub assembly in a state where a bicycle rear sprocket assembly is mounted to the bicycle rear hub assembly. The radial projection extends radially outwardly from the second axial end to restrict axial displacement of the first sprocket with respect to the sprocket support portion in the state.

A first sprocket includes a first opening having a first diameter smaller than a radially outer diameter of a sprocket support portion of a bicycle rear hub assembly. A lock member includes a main body, a male thread portion, and a radial projection. The main body has a first axial end configured to pass through the first opening and a second axial end opposite to the first axial end in an axial direction. The male thread portion is provided to the first axial end and configured to engage with a female thread portion of the bicycle rear hub assembly in a state where a bicycle rear sprocket assembly is mounted to the bicycle rear hub assembly. The radial projection extends radially outwardly from the second axial end to restrict axial displacement of the first sprocket with respect to the sprocket support portion in the state.

A bicycle sprocket includes a first sprocket body and a plurality of first sprocket teeth. The first sprocket teeth include a plurality of tooth tip portions and a plurality of tooth bottom portions. The tooth bottom portions include at least one first tooth bottom portion and at least one second tooth bottom portion. The at least one first tooth bottom portion has a first tooth bottom shape. The at least one second tooth bottom portion has a second tooth bottom shape. The first tooth bottom shape is different from the second tooth bottom shape.

A bicycle sprocket includes a first sprocket body and a plurality of first sprocket teeth. The first sprocket teeth include a plurality of tooth tip portions and a plurality of tooth bottom portions. The tooth bottom portions include at least one first tooth bottom portion and at least one second tooth bottom portion. The at least one first tooth bottom portion has a first tooth bottom shape. The at least one second tooth bottom portion has a second tooth bottom shape. The first tooth bottom shape is different from the second tooth bottom shape.

Chain-rings sets for power transmission systems, where at least one of the chain-rings is formed by independent segments provided with axial displacement means, where the segmentation is optimum both for shifts to a bigger chain-ring or a smaller chain-ring through a relative configuration between chain-rings, especially between the teeth involved in the power transmission during the shift, that ensure a smooth shift, efficient in the power transmission and reducing as possible the friction and the wear of the components.