A self-contained change speed apparatus for use on a bicycle. It has fixed shaft, a hub body rotatably supported on the fixed shaft, a change speed device controlled to turn the hub body about the fixed shaft at one of a series of speeds, and a power input member adapted to provide driving power, A clutch is moved between an active position and a non-active position and adapted to transmit driving power from the power input member to the change speed device. A control mechanism changes the speed ratio of the change speed device, advances the clutch to the non-active position before changing the speed of the change speed device, and delays the movement of the clutch to the active position, for permitting driving power to be returned to the change speed device after a change of the speed ratio of the change speed device.