Derailleur gears by 13 drive-train. Most road bicycles have two chainrings, and touring bicycles commonly have three. The rear derailleur serves double duty: moving the chain between rear sprockets and taking up chain slack caused by moving to a smaller sprocket at the rear or a smaller chainring by the front derailleur. In order to accomplish this second task, it is positioned in the path of the bottom, slack portion of chain. Sometimes the rear-derailleurs are re-purposed as chain tensioners for single-speed bicycles that cannot adjust chain tension by a different method. Although variations exist, as noted below, most rear derailleurs have
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".