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
Longest word in French Longest word in French This article lists some of the longest words in the French language. The longest word listed below, "hippopotomonstrosesquippedaliophobie" (36 letters) is the fear (or phobia) of long words. The word is formed from the Latin word "sesquipedalia" (singular "sesquipedalis"), which the Ancient Roman poet Horace used in "Ars Poetica" to describe excessively long words; literally, it means "a foot-and-a-half long". The length of the word "hippopotomonstrosesquippedaliophobie" is embellished with the prefix "hippopotomonstro" ("monster hippopotamus"), which is a characterisation of the feared words. Like the other phobias in the list, "hippopotomonstrosesquippedaliophobie" can be pluralised by adding the