Can't select smallest chainring on triple

Slurp

My front derailleur has stopped shifting to the smallest of chainwheels on my triple setup. It worked for several years without a problem, but has recently just stopped. Nothing else on the bike has changed.

I tried the radical idea of cleaning the mechanism and lubricating, but that doesn't seem to have had an effect.

I can *manually* shift it down if I get off the bike and push the mechanism, which feels quite stiff, but that's not always the most convenient approach.

I believe that loosening the cable is meant to let the chain slip down, but am surprised at this turn of events. Surely the cable would have stretched naturally and at this stage I'd need to tighten it, not the other way round? Is this a signal that this is time to change the cable? Change the derailleur?

ColinJ

I think that your derailleur is probably starting to wear.

I had the same problem mid-ride on my Basso and it was starting to really bug me. I sorted it out in about 5 seconds by squeezing the outermost part of the derailleur 'cage' in by a couple of mm, just enough to counteract the wear. That did the trick and I'm still using the same derailleur months later, no problem.

alfablue

This is a long shot, but it happened to me and stumped me for a while, had me thinking it was "new mech time". My rear mudguard had moved on the chainstay bridge by about 5mm and it was stopping the mech moving to the lowest gear. Probably not your issue, just thought I would chip in just in case.

Jamey

I also had problems with my rear mudguard obstructing the front mech but rather than having moved the problem was actually that the LBS (prior to me picking the bike up when I bought it) had fitted mudguards that were one size too wide for the tyres.

My solution was perhaps slightly drastic but I ended up using one of those small, hand-held Dremel sanders to grind away a section of the mudguard so that it no longer obstructs the mech.

I could have cut a piece out instead of grinding it away but the end result looks nicer (I think) having used the sander. It's more of a rounded, crescent-y type shape than a rough square with jagged edges.

John.T

It sounds as if the mech is begining to sieze up. A good dose of WD40 and a lot of working it (by hand if need be) followed by some drylube. Then keep it lubed. You probably do not use the granny much so it has clogged up a bit.

John C.

I agree with John T , fairly typical problem this time of year with all the salt on the road, especcially if it isn't used very much. I tend to use engine oil from an oil can rather than dry lube but that's up to you.

John.T

I find that drylube goes in better due to the 'carrier' solvent in it. Once it is free you can use anything you like.

Slurp

Thanks all for the observations. I'll try the WD40, work it and lube approach first I think. I know there's no obstruction and I don't really want to deform the mech unless the alternative is a complete replacement, which I'd rather avoid.

oldwelshman

Release the cable completey. If it still does not go down, remove it and soak it in diesel or more enviromentally friendly de greaser to release tension spring.