a mechanism for changing gear on bicycles, consisting of a device that lifts the driving chain from one sprocket wheel to another of different size
Word origin
French dérailleur derailer
derailleur in American English
(dəˈreɪlər)
noun
a gear-shifting mechanism on a bicycle for controlling its speed by shifting the sprocket chain from one to another of a set of different-sized sprocket wheels
Word origin
Fr dérailleur, derailer, with reference to the “derailing” of the chain from the sprocket