The disclosure provides a bicycle rear derailleur including a linkage assembly, a chain guiding assembly, a first assembling component, a first elastic component and a locking mechanism. The linkage assembly is a four-link mechanism and includes a fixed component, a movable component, a first link and a second link. The chain guiding assembly is pivotably connected to the movable component. The first assembling component is pivotably connected to the movable component and disposed between the first assembling component and the chain guiding assembly. The opposite ends of the first elastic component are respectively fixed to the movable component and the first assembling component so as to provide a torque that allows the first assembling component to be pivotable with respect to the movable component.