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
Glossary of French expressions in English Glossary of French expressions in English Around 45% of English vocabulary is of French origin, most coming from the Anglo-Norman spoken by the upper classes in England for several hundred years after the Norman Conquest, before the language settled into what became Modern English. Thoroughly English words of French origin, such as "art", "competition", "force", "machine", "money", "police", "publicity", "role", "routine" and "table", are pronounced according to English rules of phonology, rather than French, and are commonly used by English speakers without any consciousness of their French origin. This article, on the other hand, covers French words and phrases that