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
Influence of French on English the century, to Henri VI and Marguerite in the 15th century, all kings of England married French princesses. These marriages made French the language of the English court for several centuries and were decisive in strengthening the use of French in England. This period (12th-15th centuries) is characterized by a massive influx of French words into Old English vocabulary. In 1204, under Philippe Auguste, Normandy was officially annexed to the Capetian royal demesne (previously, Normandy, though part of French kingdom, was largely autonomous, under the authority of its dukes, kings of England), politically isolating England from the continent. Normans who