derailleur
noun
de·rail·leur
di-ˈrā-lər 
: a mechanism for shifting gears on a bicycle that operates by moving the chain from one set of exposed gears to another
Examples of derailleur in a Sentence
Recent Examples on the Web
That dynamo in turn charges a lithium-ion capacitor, which powers the derailleur's gear-shifting actuator.
—
Ben Coxworth, New Atlas, 5 June 2025
External derailleurs—the fiddly fragile mechanisms that shift a chain between cogs—are easily damaged, are hard to service in the field, and don’t work well in muddy or dusty conditions.
—Carlton Reid, Forbes.com, 11 Apr. 2025
The cranks typically have two chainrings and drive a chain that runs under the seat and to the rear axle, where there's a standard derailleur.
—John Timmer, Ars Technica, 12 May 2024
Lectric Rounding out the key specs, an 8-speed Shimano Altus derailleur provides an extra cog compared to the previous model, a suspension fork absorbs some of the bumps along the way, and 20-inch rims wear 3-inch mixed-terrain tires with custom tread and slime (for puncture resistance).
—Paul Ridden
may 07, New Atlas, 7 May 2025
See All Example Sentences for derailleur
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Ben Coxworth, New Atlas, 5 June 2025
External derailleurs—the fiddly fragile mechanisms that shift a chain between cogs—are easily damaged, are hard to service in the field, and don’t work well in muddy or dusty conditions.
—Carlton Reid, Forbes.com, 11 Apr. 2025
The cranks typically have two chainrings and drive a chain that runs under the seat and to the rear axle, where there's a standard derailleur.
—John Timmer, Ars Technica, 12 May 2024
Lectric Rounding out the key specs, an 8-speed Shimano Altus derailleur provides an extra cog compared to the previous model, a suspension fork absorbs some of the bumps along the way, and 20-inch rims wear 3-inch mixed-terrain tires with custom tread and slime (for puncture resistance).
—Paul Ridden
may 07, New Atlas, 7 May 2025
See All Example Sentences for derailleur
Cite this Entry
“Derailleur.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/derailleur. Accessed 10 Jul. 2025.
Copy CitationKids Definition
derailleur
noun
de·rail·leur
di-ˈrā-lər
: a device for shifting gears on a bicycle that operates by moving the chain from one set of exposed gears to another
Etymology
from French dérailleur "gear changing device," from dérailler "to derail"
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