CG125 motorcycle reduction gear, gear number, shaft hole size and CG125 transmission/transmission system fully match, directly replace the original reduction gear, compatible with the corresponding transmission parts, without the need to modify the system structure; It adopts the integrated design of large and small double teeth, which can accurately connect the transmission parts of different speeds, ensure the smoothness of power transmission, and avoid slipping and abnormal sound during transmission. Using high quality alloy steel forging + surface hardening treatment, tooth surface hardness, wear resistance, can withstand long-term transmission load and impact, service life and the original factory; Precise tooth shape processing can improve power transmission efficiency, reduce transmission loss, so that the vehicle power output is smoother.