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Bicycle Repair/Shimano ST-CT15 rear shifter


I recently acquired this bike at a public auction. It is a 21 speed. I brought it home and went out for a test drive. I went through the rear ranges (1-7) and then went to downshift and nothing happened. I thought the cable might have been loose but I did tighten it up and it still would not shift. The lever just moves freely back and forth with no action in the cable at all. The same thing happened to the front shifter. It still works but it has trouble getting into the third and first range. I think the front shifter it might just be the cable being loose, but I'm not sure. It is right now stuck in 14 gear. 2nd range for the front shifter and high gear for the rear shifter.

Bikes that have sat around for a long period of time without any use  commonly exhibit this problem.

What has happened is that the lube/grease in the shifter mechanisms on the handlebars has hardened to the point of preventing the ratcheting pawl mechanism from returning to its rest position

You can try spraying or squirting some kind of degreaser/solvent  (isopropyl, or "rubbing" alcohol is cheap/safe/easy to find) into the "guts" of the shifter mechanisms while working the shifter levers. It may take a while for the alcohol to soften the grease/wax, so give it time.

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James Novak


I can answer most inquiries with respect to bicycle assembly, repair, tuning and maintenance. I am less than inclined to speak on such questions as "What kind of bike should I buy?", &/or "What is this bike worth?", etc. Any answers to these types of questions may correlate poorly to an acceptable "fact/sarcasm" ratio.


7 seasons of "Professional" bicycle service/repair, etc. 4 seasons as Instructor, Professional Bicycle Mechanic training college. n-1 seasons of riding, cracking, crushing, mutilating and breaking bikes of any & all varieties, and thus requiring intense and at-hand skills development, etc.

Certified Professional Bicycle Mechanic; Winterborne Bicycle Institute/Conestoga College

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The Hub Bicycle Shop, Hespeler Winterborne Bicycle Institute

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