The multi-stage flywheel is based on the single-stage flywheel, adding several flywheel plates and combining them with the sprocket on the central shaft to form various transmission ratios, thus changing the speed of the bicycle.

The chain, also known as vehicle chain and roller chain, is installed on the coupling wheel and flywheel. Its function is to transfer the pedal force from the crank and sprocket to the flywheel and rear wheel to drive the bicycle forward.