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 English likely to be encountered in general text are "deinstitutionalization" and "counterrevolutionaries", with 22 letters each. A computer study of over a million samples of normal English prose found that the longest word one is likely to encounter on an everyday basis is "uncharacteristically", at 20 letters. The word "internationalization" is abbreviated "i18n", the embedded number representing the number of letters between the first and the last. In his play "Assemblywomen" ("Ecclesiazousae"), the ancient Greek comedic playwright Aristophanes created a word of 171 letters (183 in the transliteration below), which describes a dish by stringing together its ingredients: Henry Carey's farce