Abstract: A bicycle speed change mechanism in which five speeds are obtained with mechanism contained internally within the hub of a bicycle wheel. A pair of planetary gear mechanisms are mounted on a hub axle within a hub body, and two separate speed change rods are provided to selectively and separately control operation of the planetary gear mechanisms to obtain five numerically-different drive ratios. The separate speed change rods are manipulated at the control of the bicycle rider to select gear ratios ranging from the lowest to the highest available gear.

Abstract: The present invention relates to an internally accommodated three-stage speed change mechanism and an internally accommodated five-stage speed mechanism applicable to a bicycle, in which inside a hub body incorporating a portion of a speed change mechanism a first planetary gear mechanism is accommodated and a first speed changing rod is provided for controlling the first planetary gear mechanism, the ring gear of which is slidably moved by first the speed changing rod and the planetary gear of which remains axially fixed regardless of the first speed change rod.Further, a second planetary gear mechanism is assembled additionally to the aforesaid planetary gear mechanism and a second speed changing rod controlling the revolution and torque transmitting process of a sun gear of the second planetary gear mechanism is provided.