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
Influence of French on English linguist Henriette Walter, words of French origin represent more than two thirds of the English vocabulary. It is estimated by linguist Anthony Lacoudre that over 40 000 English words are directly French and may be understood without orthographical change by French speakers. At the beginning of 11th century, the English language did not have a well-defined status. Indeed, the inhabitants of what would become Great Britain did not have a language that allowed them to communicate with each other. There were many different dialectal forms. Great Britain, in which various Celtic idioms had coexisted since the fourth century, had experienced