Multi-speed gear system for a chain transmission device of a bicycle

摘要

A multi-speed gear system for a chain transmission device of a bicycle is provided. The system includes a disc having a front plate, a rear plate, and a plurality of tooth series concentrically arranged in the disc and a tooth series selector. Each of the tooth series has a plurality of tooth blocks; the front plate of the disc has a plurality of tooth holes; and the rear plate of the disc has a plurality of rear holes. Each of the tooth blocks is either pushed into a corresponding one of the tooth holes or protrude out of the front plate and the tooth series selector selects one of the tooth series to change speed and makes the tooth blocks of the selected tooth series protrude out of the front plate.