一、前言 近年来,多级变速车在国外发展迅速,日新月异,并且在不久的将来,自行车很可能从整体上发生“革命性”的变化。我国虽为自行车大国,但变速性能优良的赛车,则多从国外进口。由于我国多级变速车技术发展相对落后,其外变速系统性能不佳,加之其他零部件的加工质量及尺寸未统一,导致多 I. INTRODUCTION In recent years, multi-speed vehicles have developed rapidly abroad and are changing with each passing day, and in the near future, bicycles are likely to undergo “revolutionary” changes as a whole. Although China is a big country in bicycles, racing cars with excellent gear shift performance are imported from abroad. As China’s multi-speed vehicle technology is relatively backward, its external transmission system performance is poor, and the processing quality and dimensions of other components are not uniform, resulting in many