The working principle of its single-stage flywheel: when the pedal is stepped forward, the chain drives the flywheel to rotate forward. At this time, the inner teeth of the flywheel are combined with the kilo. The rotating force of the flywheel is transmitted to the core through the kilo. The core drives the rear axle and rear wheel to rotate, and the bicycle moves forward.

Single-stage flywheel, also known as single-chain wheel flywheel, is mainly composed of outer sleeve, flat block and core, jack, jack spring, washer, wire block, steel ball and other parts.