Derailleur gears several standards in use, and in each the product of the derailleur's actuation ratio and the length of cable pulled must equal the pitch of the rear sprockets. The following standards exist. Some rear derailleurs, especially for mountain bikes, incorporate a clutch to keep the lower length of chain in sufficient tension to prevent the chain from striking the bottom of the chain stay, called "chain slap", and which can damage the chain stay. Clutches are also helpful in preventing the chain from derailing from the chain ring on systems without a front derailleur. The front derailleur only has to
Quebec French lexicon examples of long-standing Anglicisms include: It is also very commonplace for an English word to be used as a nonce word, for example when the speaker temporarily cannot remember the French word. This is particularly common with technical words; indeed, years ago before technical documentation began to be printed in French in Quebec, an English word might be the most common way for a French-speaking mechanic or other technical worker to refer to the mechanisms he or she had to deal with. It is often difficult or impossible to distinguish between such a nonce Anglicism and an English word quoted