1. General method: first put down the crank, then put down the central shaft on one side of the crank, and finally remove the whole toothed plate (the idea is to cut off the chain or remove the toothed plate), and then install a new toothed plate as you do.

2. There are three kinds of bicycle tooth plates: square hole, spline and hollow. Hollow is the tooth plate of high-grade car, which is a common square hole and spline for civil use. The three spindles are different, so are the wrenches.