自行车如何变速

Bicycles change gears by using a system of gears and derailleurs. The gear system on a bicycle typically consists of a front chainring with multiple teeth sizes and a rear cassette with multiple gears. By shifting the chain between different combinations of front and rear gears, the rider can adjust the resistance and speed at which they are pedaling. This allows the rider to maintain an optimal cadence for different terrains and conditions.

Would you like a code sample or more information on how this works