Medic Zero

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Curious about the signs and symptoms of front derailleur pivots being worn out.

I never would've thought it really being a possibility, but I once had a bike mechanic I trusted helping me build up a used bike and he said that was the case with the FD, so I swapped it for one from my parts pool.

Now, on my commuter, I've been having problems where the bike shifts itself into the smallest chainring and when I try and shift it back up it won't stay there. Acts like there is a spring or tension pulling it back down. Sometimes, if I hold the (friction) shifter in place, in the position of the middle or large chainring, it'll stay, sometimes (usually) it won't.

I've tried replacing the cable and housing, because at first I thought the shifter had ingested a bit of rubber band, and that was causing it, but the problem persists with the new cable and housing and a thorough cleaning of the shifter, although I suppose there's a small possibility that there is a bit of rubber hiding in there causing the issue.

Friction shifting, triple, bottom pull. Don't recall the provenance of this particular derailler from my parts pool, but it was used before I started using it, and I've put right about 5,000 miles on it since then. It worked fine for first couple of years of those miles. FWIW, I shift a LOT.

Is there any other possiblity here, or is it just time for a new FD?


Many thanks!

dsbrantjr

It sounds like you are having a problem with your shifter not staying in place, not with the derailleur. Most of them have an adjustment screw which needs to be tightened to hold the shifter setting. This screw often needs a lot of force to tighten it sufficiently. Many friction shifters have small plastic parts inside, one of which may be defective.

cny-bikeman

Agreed. The derailleur stays in place for as long as it is held there by the cable. Worn pivots (very rare) would only affect the efficiency of shifting.

Hoopdriver

Should be pretty easy to see slop due to worn pivots; however I would think that other reasons are more likely for your issue. Assuming that your shifters are functioning correctly, a FD with worn pivots would still stay where you put it.

I wonder how frequent pivots wear out in FDs anyway. Unless you are set up for half-step shifts (a pattern that I really have learned to appreciate), the FD gets only a small proportion of use compared to the RD.

Try a different shifter to see what happens. Also curious to your reference of rubber bands - I have no idea what this is about. Where would these rubber bands come from?

dsbrantjr

An improvised repair, trying to make a slipping shifter hold, would be my bet.

Medic Zero

My Airzoundz horn is mounted right next to the shifter. The horns mount became worn over time and was loose. I was using a rubber band wrapped around it to hold it in place. This rubber band ran around the front of the shifter unit. Sun and weather did a number on it, and it decayed into pieces, one of which appeared to have been ingested by the shifter. Initially I had hoped that this was the issue. Hate to think it's the nice old Suntour shifter failing, but from everyone's responses (THANKS!) it sounds like that's the issue. I've got some lower quality shifters kicking around in the parts boxes somewhere, I'll dig one of them up this week, and give that a try.

THANKS EVERYONE!





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