A bicycle rear derailleur includes a base member having a first portion and a second portion. The first portion of the base member is mountable to a bicycle frame, and the second portion of the base member is attached to the first portion of the base member and includes at least a portion of a power supply attachment. The bicycle rear derailleur also includes a movable member movably coupled to the first portion of the base member and electrically connected to the second portion of the base member. The bicycle rear derailleur includes a chain guide assembly rotatably connected to the movable member.