derailleur

剑桥词典

a type of bicycle gear that works by moving the bicycle chain from one sprocket wheel (= a wheel with a row of tooth-like parts ) to another
（自行車的）換擋裝置，變速器
Set the rear derailleur in the lowest gear , with the chain on the biggest sprocket wheel at the back. 把後輪的變速器調到最低擋，就是讓鏈條在後麪連到最大的鏈齒上。
derailleur gears 換擋齒輪 返回 derailleur