Bicycle Mechanics - Adjusters self-adjusting!
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09-16-09, 08:57 AM
I have in-line cable tension adjusters (long barrels) on the cables coming out of my Shimano STI shifters (Sora). While the one for the front derailleur stays put, I find that the adjuster for the rear derailleur regularly loosens and requires re-tightening mid-ride.
What could the reason for this be, please?
09-16-09, 09:26 AM
A. Cable-slippage at the pinch-bolt?
B. Normal-stressing of the cable as you change gears?
09-16-09, 10:34 AM
Check that the ferrule is spinning freely in the adjuster. If not, turning the adjuster will simply wind up the housing like a nipple seized on a spoke. The vibration from riding will eventually cause the housing to untwist and spin the adjuster back to it's original starting point. I only suggest this really odd sounding problem as the cause because it happened to me. Corrosion built up inside of the adjuster causing the ferrule to get stuck. A new ferrule and cleaning out the adjuster solved the problem.
09-19-09, 04:59 PM
Thanks guys. It's definitely not cable slippage on the pinch bolt and the ferrules spin freely in the ends of the adjuster. I wonder if the spring inside the adjuster has snapped or something? I'm assuming there is a spring in there?
09-19-09, 06:05 PM
It's possible that the detents that hold the position of the adjuster are worn. You can try removing the adjuster and filing the grooves deeper to restore the detents.
09-20-09, 06:06 PM
I don't think there are any detents as this is not an indexed adjuster, just a regular threaded one. I've seen in another thread that people have applied Loctite to the threads to keep them from unscrewing, so I will give that a go...
09-20-09, 10:50 PM
There should be a locknut that you can use to lock the assembly. It's a small threaded ring at the end.
09-20-09, 11:21 PM
Most inline cable adjusters don't have a spring. I have the same problem using an inline adjuster with my Nexus internal gear hub. With no spring to provide stable tension, the barrel is free to self-adjust as the bike is shifted and the tension in the cable fluctuates.
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