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
Oxford-Hachette French Dictionary: French–English English–French Oxford-Hachette French Dictionary: French–English English–French The Oxford-Hachette French to English/English to French Dictionary is one of the most comprehensive and recent bilingual French–English/English–French dictionaries. It was the first such dictionary to be written using a computerized corpus and it contains 555,000 translations as well as 360,000 words and expressions. The work was first published in 1994, with its second, third and fourth editions appearing in 1997, 2001 and 2007 respectively. Though the dictionary is entirely bilingual, it is marketed under two different names, one for French, one for English: Its version is also available in a concise or condensed version.