Derailleur gears operates the lever while pedalling, the change in cable tension moves the chain-guide from side to side, "derailing" the chain onto different sprockets. For more information about the choice of particular gear ratios and sprocket sizes, see Bicycle gearing. "Derailleur" is a French word, spelled "dérailleur" in French, derived from the derailment of a train from its tracks. Its first recorded use was 1930. At least one notable bicycle industry author has attempted to promote the anglicized spelling of "derailer". As of 2013, however, neither Merriam-Webster nor the Oxford English Dictionary has an entry for "derailer". Various derailleur systems were
Glossary of French expressions in English Glossary of French expressions in English Around 45% of English vocabulary is of French origin, most coming from the Anglo-Norman spoken by the upper classes in England for several hundred years after the Norman Conquest, before the language settled into what became Modern English. Thoroughly English words of French origin, such as "art", "competition", "force", "machine", "money", "police", "publicity", "role", "routine" and "table", are pronounced according to English rules of phonology, rather than French, and are commonly used by English speakers without any consciousness of their French origin. This article, on the other hand, covers French words and phrases that