Derailleur gears by 13 drive-train. Most road bicycles have two chainrings, and touring bicycles commonly have three. The rear derailleur serves double duty: moving the chain between rear sprockets and taking up chain slack caused by moving to a smaller sprocket at the rear or a smaller chainring by the front derailleur. In order to accomplish this second task, it is positioned in the path of the bottom, slack portion of chain. Sometimes the rear-derailleurs are re-purposed as chain tensioners for single-speed bicycles that cannot adjust chain tension by a different method. Although variations exist, as noted below, most rear derailleurs have
Football (word) brother plays football in the States", it would be clear from context that American football is meant. Canadian French usage parallels English usage, with "le football" usually referring to Canadian or American football, and "le soccer" referring to association football. When there is ambiguity, "le football canadien" or "le football américain" is used. Rugby union football in Canada is almost always referred to simply as "rugby". In most of the English-speaking Caribbean, "football" and "soccer" are both used to refer to association football, but use of the word "football" is far more common. The exception is the Bahamas, where the