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 Several elements must be observed. The following French glossary in English is in no way exhaustive. These words come as examples to illustrate the countless French words that are part of the English language. In this section, examples of French-to-English lexical contributions are classified by field and in chronological order. The periods during which these words were used in the English language are specified as much as possible. It is not always possible to state with certainty the precise period from which a word was borrowed or integrated. The English word is on the left, with its current French equivalent