A derailleur comprises a base member, a movable member, a linkage structure, a pulley assembly, and a rotational force control structure configured to control rotational force of the pulley assembly relative to the movable member. The pulley assembly is pivotally movable relative to the movable member about a pivot axis in first and second directions. The pulley assembly is configured to move in the first direction upon moving from a second pivotal position toward a first pivotal position. The rotational force control structure includes a cam member having a first cam surface, an abutment member configured to abut the first cam surface, and a biasing member configured to bias the abutment member. The abutment member is configured to abut the first cam surface by the biasing member to apply first additional force to the pulley assembly in the first direction while the pulley assembly is in the first pivotal position.

A derailleur comprises a base member, a movable member, a linkage structure, a pulley assembly, and a rotational force control structure configured to control rotational force of the pulley assembly relative to the movable member. The pulley assembly is pivotally movable relative to the movable member about a pivot axis in first and second directions. The pulley assembly is configured to move in the first direction upon moving from a second pivotal position toward a first pivotal position. The rotational force control structure includes a cam member having a first cam surface, an abutment member configured to abut the first cam surface, and a biasing member configured to bias the abutment member. The abutment member is configured to abut the first cam surface by the biasing member to apply first additional force to the pulley assembly in the first direction while the pulley assembly is in the first pivotal position.

A bicycle gearshift mechanism has a base element, a pivot mechanism, a movable element, and a chain guide arrangement. The pivot mechanism connects the base element to the movable element. The chain guide arrangement is connected, rotatably about a rotary axle, to the movable element. The base element comprises a first attachment end, which is coaxial with respect to the rear-wheel axle or axis, and a second attachment end for coupling to the pivot mechanism

A bicycle gearshift mechanism has a base element, a pivot mechanism, a movable element, and a chain guide arrangement. The pivot mechanism connects the base element to the movable element. The chain guide arrangement is connected, rotatably about a rotary axle, to the movable element. The base element comprises a first attachment end, which is coaxial with respect to the rear-wheel axle or axis, and a second attachment end for coupling to the pivot mechanism

A bicycle rear derailleur has a base member mountable to a bicycle frame, a movable member movably coupled to the base member, a chain guide assembly rotatably connected to the movable member for rotation about a rotational axis, a biasing element configured and arranged to bias the chain guide assembly for rotation in a first rotational direction with respect to the movable member, and a fluid damper having a fluid cavity containing a volume of fluid. The fluid damper is operatively disposed between the chain guide assembly and the movable member to apply a damping force to the chain guide assembly when the chain guide assembly rotates in a second rotational direction opposite to the first rotational direction. The fluid damper has a guide wheel configured to route a chain and rotatable about the rotational axis.

A bicycle rear derailleur has a base member mountable to a bicycle frame, a movable member movably coupled to the base member, a chain guide assembly rotatably connected to the movable member for rotation about a rotational axis, a biasing element configured and arranged to bias the chain guide assembly for rotation in a first rotational direction with respect to the movable member, and a fluid damper having a fluid cavity containing a volume of fluid. The fluid damper is operatively disposed between the chain guide assembly and the movable member to apply a damping force to the chain guide assembly when the chain guide assembly rotates in a second rotational direction opposite to the first rotational direction. The fluid damper has a guide wheel configured to route a chain and rotatable about the rotational axis.

A rear derailleur assembly for mounting to a bicycle having a frame. The rear derailleur assembly includes an upper body portion configured to operationally engage the rear derailleur assembly to the frame, a controller portion pivotally connected to the upper body, a lower body portion pivotally connected to the upper body and pivotally connected to the controller portion, and a chain cage assembly. The chain cage assembly includes at least two pulleys configured to engage a chain of the bicycle, and a one-piece chain cage configured to retain each pulley at a particular fixed position. Each pulley is rotatable relative to the one-piece chain cage at the particular fixed position of the pulley. The lower body portion is operationally connected to the one-piece chain cage and configured to allow the one-piece chain cage to pivot relative to the lower body portion.

A rear derailleur assembly for mounting to a bicycle having a frame. The rear derailleur assembly includes an upper body portion configured to operationally engage the rear derailleur assembly to the frame, a controller portion pivotally connected to the upper body, a lower body portion pivotally connected to the upper body and pivotally connected to the controller portion, and a chain cage assembly. The chain cage assembly includes at least two pulleys configured to engage a chain of the bicycle, and a one-piece chain cage configured to retain each pulley at a particular fixed position. Each pulley is rotatable relative to the one-piece chain cage at the particular fixed position of the pulley. The lower body portion is operationally connected to the one-piece chain cage and configured to allow the one-piece chain cage to pivot relative to the lower body portion.

A bicycle rear derailleur includes a base member including a mounting portion configured to be attached to a bicycle frame, the mounting portion having a mounting opening through which a central axis of a hub axle passes in a mounting state of the bicycle rear derailleur. The mounting portion includes a single joint or is free of any joint. Also included is a movable member movably coupled relative to the base member and a linkage structure operatively connecting the movable member to the base member. Also included is at least one of a motor, a first wireless communication unit, and an electrical connector. The at least one of the motor, the first wireless communication unit, and the electrical connector are disposed on at least one of the base member, the movable member, and the linkage structure.

The derailleur has a damper that breaks the angular movements of a chain guide. Variable volume chambers in the damper are filled with a damping fluid and connected through a controlled fluid passage system so that fluid flows between chambers in response to angular movement of the chain guide. The damper comprises a dividing body in a mobile body coaxial to the axis X, mechanically constrained so that each rotation of the dividing body about the axis X is accompanied by a translation of the dividing body along the axis X. The dividing body is mechanically constrained to the chain guide and moves with it in the angular direction about the axis X. The chambers are formed in the mobile body on opposite sides of the dividing body and change volume in opposite directions when the dividing body moves along the axis X.