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
English claims to the French throne of Aquitaine. However, in 1337, Edward, in his capacity as Duke of Aquitaine, refused to pay homage to Philip. The French king's response was to confiscate what was left of lands in English held Aquitaine, namely Gascony, thus precipitating the Hundred Years' War and Edward's revival of his claim to the throne and title of King of France in 1340. The decision to assume the title of "King of France" was made at the solicitation of his Flemish allies, who had signed a treaty that they would no longer attack the French king. They said that if Edward took the