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 French royal title, then the Flemish would be able to keep their honor, since they would not be attacking the "true King of France" (Edward III). Edward continued to use this title until the Treaty of Brétigny on 8 May 1360, when he abandoned his claims in return for substantial lands in France. After the resumption of hostilities between the English and the French in 1369, however, Edward resumed his claim and the title of King of France. His successors also used the title until the Treaty of Troyes on 21 May 1420, in which the English recognised Charles VI