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
The Big Machine The Big Machine The Big Machine is the fourth studio album by French singer, composer and producer Émilie Simon, released on 14 September 2009, by Barclay. The album is completely in English; no French songs were included on the album. However, some songs have fragments in French. Four viral videos have been posted on her official MySpace page. The videos include the same artwork used on her official website, created by AATOAA. The first one includes the full album version of "Dreamland" which is the lead single of the album. The second one includes a 36-second instrumental sample of "Chinatown".