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
Names for the number 0 in English Names for the number 0 in English Zero is the usual name for the number 0 in English. In British English "nought" is also used. In American English "naught" is used occasionally for zero, but as with British English, "naught" is more often used as an archaic word for nothing. "Nil", "love", and "duck" are used by different sports for scores of zero. It is quite common in English to describe decades with a plural of the first year of the decade for example "the nineties" which can be written as "the 90s". There was a debate on what to