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 states like New-Brunswick, Quebec, Ivory Coast, Benin, Togo, Guinea, Cameroon, Congo, Democratic Republic of the Congo, Madagascar, Mauritius, Tchad, Djibouti, Senegal, Morocco, Algeria, Tunisia, Lebanon, France, Belgium, Switzerland, Luxembourg, Monaco, Aosta Valley, French Polynesia, New Caledonia, and Vanuatu adopting it as their official language. This geographical diversity has led to many different contacts with vernacular dialects, regional and international languages, from which French has often been enriched locally. In a number of countries and regions where French shares co-officiality with English (Cameroon, Canada, Jersey, Mauritius, Rwanda, Vanuatu), particular lexical regionalisms are observed where French and English terms are used interchangeably.