1、 Solution: Method 1: Replace the old flywheel and old chain together; Method 2: Forcibly ride and run in for a period of time in the case of tooth jumping and chain jumping , The running‑in time is long or short, depending on the wear of the chain.2、 Flywheel material: Steel, wear‑resistant, fine stamping tooth profile, 3‑layer nickel‑chromium electroplated silver anti‑rust, easy climbing, precise positioning, tooth profile rigid and wear‑resistant, effective transmission, exquisite high‑end, no rust!3、 The mountain flywheel is made of high‑strength steel and adopts hardening technology, which has greater resistance, durability and wear resistance. The mud drain hole makes it easier to drain the mud, which is convenient for the cleaning and maintenance of the box body.4、 Easy to install: This bicycle flywheel is easy to install, without any adjustment, is more convenient to use, and effectively saves your time.5、 If your chain riding time is too long, it is recommended not to replace the flywheel at will. Replacement of a new flywheel will cause the tooth jumping and chain jumping, which will affect normal riding