derailleur

American  

[dih-rey-ler] / dɪˈreɪ lər /

noun

1. a gear-shifting mechanism on a bicycle that shifts the drive chain from one sprocket wheel to another.

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derailleur British  

/ dəˈreɪljə /

noun

1. 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

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Etymology

Origin of derailleur

1945–50; < French dérailleur literally, a device causing disengagement or derailing, equivalent to déraill ( er ) to derail + -eur -eur

Explanation

The part of your bicycle consisting of a chain that moves from one toothed wheel to another when you shift gears is called a derailleur. The French dérailleur, first used around 1930, was inspired by the way a train derails from its tracks, the wheels slipping off to one side. On a bike, this happens on purpose, part of the process of shifting from one gear into another: The chain "derails" off one sprocket and onto another. Before the invention of this device, cyclists had to change their wheels in order to climb steep hills. Most modern bicycles have two derailleurs, in front and back.

Example Sentences

But Derailleur Brew Works, a craft brewery in the Japanese city of Osaka, is helping transform this unfashionable district with the help of men and women who once thought they were unemployable.

From The Guardian • Jan. 11, 2020

Derailleur has produced 30 varieties of beer over the past two years, including a limited-edition stout, a mixed-juice IPA and Riot Ale, its most popular type.

From The Guardian • Jan. 11, 2020

With a bank loan and instruction on making beer from a sympathetic brewer, Derailleur produced its first batch in 2018 – an American pale ale named Nishinari Riot Ale.

From The Guardian • Jan. 11, 2020

Derailleur employs about 70 people, many of whom have physical and intellectual disabilities.

From The Guardian • Jan. 11, 2020