US Patent 10189542 Bicycle rear derailleur

A bicycle rear derailleur is provided, which includes a base adapted to be mounted on a bicycle frame, a movable member, a linkage assembly pivotally connected to and between the base and the movable member, a pivot shaft provided within and pivotally rotatable relative to the movable member, a chain guide fixed to an end of the pivot shaft, a restriction assembly provided on the pivot shaft, and a friction assembly provided within the movable member to provide a rotational friction on the restriction assembly. Whereby, the chain guide is pivotally awing toward a first direction by a force; when the chain guide swings toward a second direction which is opposite to the first direction by another force, it is forced by a swing resistance.