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
French corsairs of the French Crown, if captured by the enemy, they could in principle claim treatment as prisoners of war, instead of being considered pirates. Because corsairs gained a swashbuckling reputation, the word "corsair" is also used generically as a more romantic or flamboyant way of referring to privateers, or even to pirates. The Barbary pirates of North Africa as well as the Ottoman Empire were sometimes called "Turkish corsairs". The word "corsair" comes directly from the French word "corsaire", itself borrowed from the Italian "corsaro". This derives from the Latin "cursus", meaning "course" (as in journey or expedition). The French