A derailleur basically includes a base member, a movable member and a linkage assembly. The base member includes a first base member connecting section and a second base member connecting section. The movable member includes a first movable member connecting section and a second movable member connecting section. The linkage assembly includes an inner link member and an outer link member. The outer link is pivotally coupled to the second base member connecting section about a third pivot axis. The outer link is pivotally coupled to the second movable member connecting section about a fourth pivot axis. The outer link member has a power source receiving part that is configured to be arranged such that the power source receiving part traverses a reference line extending between the third pivot axis and the fourth pivot axis.

A bicycle rear derailleur is configured to be mounted on a wheel shaft on a bicycle frame. The bicycle rear derailleur includes a base component, a movable component, a linkage assembly, a chain guide, and a mount assembly. The base component is configured to be mounted on the bicycle frame. Two opposite ends of the linkage assembly are pivotally disposed on the base component and the movable component respectively. The chain guide is pivotally disposed on the movable component. The mount assembly includes an adapter, a bushing, and a fastener. The adapter is configured to be fixed on the bicycle frame. The base component is stacked on the adapter. The bushing is configured to be disposed through the bicycle frame, the adapter and the base component and is configured for an insertion of the wheel shaft. The fastener is fastened on the bushing.

A bicycle rear derailleur is configured to be mounted on a wheel shaft on a bicycle frame. The bicycle rear derailleur includes a base component, a movable component, a linkage assembly, a chain guide, and a mount assembly. The base component is configured to be mounted on the bicycle frame. Two opposite ends of the linkage assembly are pivotally disposed on the base component and the movable component respectively. The chain guide is pivotally disposed on the movable component. The mount assembly includes an adapter, a bushing, and a fastener. The adapter is configured to be fixed on the bicycle frame. The base component is stacked on the adapter. The bushing is configured to be disposed through the bicycle frame, the adapter and the base component and is configured for an insertion of the wheel shaft. The fastener is fastened on the bushing.

A rear gearshift mechanism for installation on a bicycle frame coaxial with a rear-wheel axis has a base element, a pivot mechanism, a movable element and a chain guide. The base element includes an attachment end for installation on the bicycle frame. A first arm and a second arm of the attachment end are arranged spaced apart from one another in an axial direction and, by an associated adapter which has a thread, are configured for the installation of the gearshift mechanism on an associated bracket portion, in particular a dropout or frame hanger. The first arm is arranged on an inner side of the bracket portion, and the second arm is arranged on an outer side of the bracket portion. The base element is designed with a setting device by which the base element can be pivoted in a chain tensioning direction.

A rear gearshift mechanism for installation on a bicycle frame coaxial with a rear-wheel axis has a base element, a pivot mechanism, a movable element and a chain guide. The base element includes an attachment end for installation on the bicycle frame. A first arm and a second arm of the attachment end are arranged spaced apart from one another in an axial direction and, by an associated adapter which has a thread, are configured for the installation of the gearshift mechanism on an associated bracket portion, in particular a dropout or frame hanger. The first arm is arranged on an inner side of the bracket portion, and the second arm is arranged on an outer side of the bracket portion. The base element is designed with a setting device by which the base element can be pivoted in a chain tensioning direction.

A bicycle gearshift is operated by imposing on the chain guide a primary displacement in the axial direction with respect to a cogset, to move the chain between the sprockets. Simultaneously with imposing on the primary displacement imposing on the chain guide a secondary displacement in the radial direction with respect to the cogset. The secondary displacement is of a greater size when the primary displacement takes place in the area of the cogset with the larger sprockets whereas it is of a smaller size when the primary displacement takes place in the area of the cogset with the smaller sprockets.

A bicycle gearshift is operated by imposing on the chain guide a primary displacement in the axial direction with respect to a cogset, to move the chain between the sprockets. Simultaneously with imposing on the primary displacement imposing on the chain guide a secondary displacement in the radial direction with respect to the cogset. The secondary displacement is of a greater size when the primary displacement takes place in the area of the cogset with the larger sprockets whereas it is of a smaller size when the primary displacement takes place in the area of the cogset with the smaller sprockets.

A bicycle rear derailleur comprises a base member, a linkage structure, a movable member, a first pulley assembly, and a second pulley assembly. The first pulley assembly includes a first pulley support and a first toothed pulley. The first pulley support is pivotally coupled to the movable member about a first pivot axis. The first toothed pulley is rotatably coupled to the first pulley support about a first pulley axis spaced apart from the first pivot axis. The second pulley assembly includes a second pulley support, a second toothed pulley, and a third toothed pulley. The second pulley support is pivotally coupled to the movable member about a second pivot axis. The second toothed pulley is rotatably coupled to the second pulley support about a second pulley axis. The third toothed pulley is rotatably coupled to the second pulley support about a third pulley axis.

A bicycle derailleur mechanism is provided which accommodates larger radial spacing and/or smaller radial spacing having a non-uniform value over the respective winding region. The derailleur mechanism cable pull transmission device may provide over its rotational angular range about the rotational axis, which is effective during operation, a variable transmission ratio as a function of the rotational position of the cable pull transmission device relative to the base component.

A bicycle derailleur mechanism is provided which accommodates larger radial spacing and/or smaller radial spacing having a non-uniform value over the respective winding region. The derailleur mechanism cable pull transmission device may provide over its rotational angular range about the rotational axis, which is effective during operation, a variable transmission ratio as a function of the rotational position of the cable pull transmission device relative to the base component.