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 Several elements must be observed. The following French glossary in English is in no way exhaustive. These words come as examples to illustrate the countless French words that are part of the English language. In this section, examples of French-to-English lexical contributions are classified by field and in chronological order. The periods during which these words were used in the English language are specified as much as possible. It is not always possible to state with certainty the precise period from which a word was borrowed or integrated. The English word is on the left, with its current French equivalent