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
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