A bicycle rear sprocket assembly comprises a sprocket support and a first sprocket. The sprocket support includes a hub engagement part configured to engage with a bicycle hub assembly. The sprocket support includes a plurality of sprocket attachment members extending radially outwardly from the hub engagement part with respect to a rotational center axis of the bicycle rear sprocket assembly. The first sprocket is attached to the plurality of sprocket attachment members. The first sprocket includes a first sprocket body and a plurality of first sprocket teeth which extends radially outwardly from the first sprocket body with respect to the rotational center axis and a total number of which is equal to or larger than thirty-four. The first sprocket has a plurality of shifting facilitation areas. A total number of the plurality of shifting facilitation areas is a divisor of a total number of the plurality of sprocket attachment members.

A bicycle rear sprocket assembly comprises a sprocket support and a first sprocket. The sprocket support includes a hub engagement part configured to engage with a bicycle hub assembly. The sprocket support includes a plurality of sprocket attachment members extending radially outwardly from the hub engagement part with respect to a rotational center axis of the bicycle rear sprocket assembly. The first sprocket is attached to the plurality of sprocket attachment members. The first sprocket includes a first sprocket body and a plurality of first sprocket teeth which extends radially outwardly from the first sprocket body with respect to the rotational center axis and a total number of which is equal to or larger than thirty-four. The first sprocket has a plurality of shifting facilitation areas. A total number of the plurality of shifting facilitation areas is a divisor of a total number of the plurality of sprocket attachment members.

A bicycle hub assembly comprises a hub axle, a hub body, a sprocket support structure, and a brake-rotor support structure. The sprocket support structure includes a first torque-transmitting profile and a first externally-threaded portion. The first torque-transmitting profile is configured to transmit a rotational force between the sprocket support structure and a bicycle sprocket assembly. The first externally-threaded portion is configured to threadedly engage with a first internally-threaded portion of a first lock member. The brake-rotor support structure includes a radially external surface, a radially internal surface, and a second torque-transmitting profile configured to transmit a rotational force between the brake-rotor support structure and a brake rotor. The second torque-transmitting profile is provided on the radially external surface.

A bicycle hub assembly comprises a hub axle, a hub body, a sprocket support structure, and a brake-rotor support structure. The sprocket support structure includes a first torque-transmitting profile and a first externally-threaded portion. The first torque-transmitting profile is configured to transmit a rotational force between the sprocket support structure and a bicycle sprocket assembly. The first externally-threaded portion is configured to threadedly engage with a first internally-threaded portion of a first lock member. The brake-rotor support structure includes a radially external surface, a radially internal surface, and a second torque-transmitting profile configured to transmit a rotational force between the brake-rotor support structure and a brake rotor. The second torque-transmitting profile is provided on the radially external surface.

A hub for bicycles or the like including a hub shell which is rotatably supported relative to a hub axle, a rotor rotatably supported relative to the hub axle, and a freewheel device having two interacting freewheel components namely, a hub-side freewheel component and a rotor-side freewheel component. The two freewheel components each contain axial engagement components. The hub-side freewheel component is non-rotatably and axially fixedly connected with the hub shell. The rotor-side freewheel component is non-rotatably connected with the rotor and is movable in the axial direction relative to the rotor and the hub shell between a freewheel position and an engagement position. Rolling members are provided for defined accommodation in the hub-side freewheel component to support the hub shell relative to the hub axle. The hub-side freewheel component is connected with the hub shell through a multiple thread having at least two separate, axially spaced apart thread grooves.

A bicycle hub includes a housing, in which a first ratchet device, a second ratchet device, and an elastic device are received. The first ratchet device is rotated freely in the housing, and the second ratchet device is fixed to the housing. The first ratchet device has a first ratchet portion, the second ratchet device has a second ratchet portion, and the elastic device urges the first ratchet portion to engage the second ratchet portion of the second ratchet device when the first ratchet device is rotated in a direction. A driving device is connected to the first ratchet device to rotate at an end of the housing while the first and the second ratchet portions are located at an opposite end of the housing.

A bicycle hub includes a housing, in which a first ratchet device, a second ratchet device, and an elastic device are received. The first ratchet device is rotated freely in the housing, and the second ratchet device is fixed to the housing. The first ratchet device has a first ratchet portion, the second ratchet device has a second ratchet portion, and the elastic device urges the first ratchet portion to engage the second ratchet portion of the second ratchet device when the first ratchet device is rotated in a direction. A driving device is connected to the first ratchet device to rotate at an end of the housing while the first and the second ratchet portions are located at an opposite end of the housing.

A final drive seal guard for a track-type tractor comprising a base component adapted to be stationarily fixed to the tractor and to surround a portion of a spindle housing of the final drive, a sprocket component adapted to be carried on and surround a portion of a sprocket hub of the final drive that rotates about an axis, and an intermediate component adapted to be bolted over the exterior of one of said base and sprocket components and surround portions of both of said base and sprocket components, the intermediate component and another of said base or sprocket components being mutually arranged to form a radially extending sealing gap at a potential path of debris into the guard at a location free of a relatively long axial gap upstream in said potential path.

A final drive seal guard for a track-type tractor comprising a base component adapted to be stationarily fixed to the tractor and to surround a portion of a spindle housing of the final drive, a sprocket component adapted to be carried on and surround a portion of a sprocket hub of the final drive that rotates about an axis, and an intermediate component adapted to be bolted over the exterior of one of said base and sprocket components and surround portions of both of said base and sprocket components, the intermediate component and another of said base or sprocket components being mutually arranged to form a radially extending sealing gap at a potential path of debris into the guard at a location free of a relatively long axial gap upstream in said potential path.

A bicycle rear wheel adapter has an annular body that abuts a sprocket-carrying body that extends in an axially outer direction and receives sprockets in radially peripheral positions. A coupling element on the annular body couples with the sprocket-carrying body so the adapter rotates as a unit with the sprocket-carrying body, and a sprocket-receiving seat on the annular body couples with a sprocket so the adapter rotates as a unit with the sprocket. The adapter is suitable for cogsets with small sprockets grouped in a monolithic grouping.