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
Word sort Students do not need to have strong phonics skills in order to engage in sound sorts. This can be a beginning phonemic awareness activity because students need only to identify the sound in order to complete the sort. Letter knowledge is not required, and phonemic development can mature as students do acquire more print knowledge. Picture sorts are one component of word study and are used to help beginning readers develop Concept of Word, phonological awareness, and phonics. Picture sorts most often begin with focusing on initial sound (single consonant, digraphs, or blends). By using picture sorts teachers are able