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I have a question about my front derailleur sticking occasionally. I've had this bike for a 1.7 years and have ridden it through 2 winters.

It has only been after this last winter that my front derailleur has been sticking on occasion where it's like grit has jammed in somewhere (which I'm sure it is the case). When I'm on the fly I just knock it with my heel and it will downshift and I can push the shifter hard enough to go back up when I need to.

The first time I decided to overhaul both the front and back ones. Took them apart, cleaned/degreased, regreased the two back cogs, and used WD-40 professional silicone on the rest of the parts as to not attract more dirt.

Then after about a month it got stuck again, and I couldn't see anything that could be jamming it (while it was still stiff as heck). Didn't take it apart this time just used a tooth brush and silicone again and it's fine at the moment.

I'm assuming it may be that since that the roads have been grittier/dirtier from the winter with some recent rain and slush that it may just be normal. I haven't been on the trails yet this year so I know it's not that.

Is this normal, has some kind of bur that I can't see come up and is catching grit?

EDIT: I should also note that this is a hardtail mtb that I use for trails and winter commuting (a lot of salt and grit on the roads).

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  • Does the FD mech move better if you pull the inner wire with your hand, where its exposed on the downtube/top tube? This takes the shifter out of the equation. Can you push the FD mech directly with your hand and have it move smoothly?
    – Criggie ♦
    Commented Apr 1, 2016 at 3:11
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    I thought that one time it happened, but the cable moves easily as I shift it to the lowest gear the cable has a lot of slack, but the cage is frozen in place until I knock it loose.
    – JackJack Attack
    Commented Apr 1, 2016 at 3:34
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    That suggests its not your shifter/cabling, its the derailer mech itself. Take the chain off the chainring and let it dangle, and clean the FD in-place as much as you can. Lube it with something intended for bikes. Let that sit overnight, and wipe off excess in the morning. The cage should move smoothly, with no crunch feeling. It will take one or two hands to counter the big spring and move directly. Do mind your fingers - chains and gears can bite badly. Replace the FD if doesn't it feel right. Not expensive, but fiddly to set up right. Wash your bike after every salty ride.
    – Criggie ♦
    Commented Apr 1, 2016 at 3:47

2 Answers 2

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This problem vexed me as a beginning mechanic. Here's my best guess for a solution.

Flip the bike over so it is resting bottom shell up. You'll see the cables run through a plastic piece called a cable guide. It's plastic and has two open channels for the cables to slide through, as well as gather crud. Loosen the cables, remove the guide (usually just a screw) and inspect it for cracks, etc. If it is ok, then clean it thoroughly with dish soap and a toothbrush. New ones can be had from your LBS. Check the front derailleur for freedom of movement. Clean front derailleur with a solvent and relube if necessary. Be sure to wipe the cables clean and reinstall. DO NOT LUBE THIS AREA. It will only attract dirt.

What happens (and still does for me) is that tiny bits of dirt get caught in the cable guides and cause excess friction for the cables, just enough to prevent proper shifting. I had a front mech stuck the same way you described. It doesn't take a lot to prevent a shift.

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Put some chain lube (Triflow ftw) on the pivot points of the derailleur and go through its full range of motion a few times. You should start feeling a big difference. Also, you may find replacing your cables and housing to be beneficial - very easy to do on your own and relatively cheap to be done at any local bike shop.

Tip: WD-40 is not good for bike components. Use it to free up rusted screws- that's it.

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  • That's what I do already, and while yes WD-40 original would be bad, I'm using WD-40 silicone which is a completely different formula where they call it WD-40 because that's the brand name/recognizable. So it's more comparable to dry Teflon bike chain oil. I know how to unjam it, but I'm wondering if there is anything if there if this happens to others to different variances of frequency.
    – JackJack Attack
    Commented Apr 1, 2016 at 1:24
  • I've been using the same Deore derailleurs since I got my road bike back in 2006, never had any difficulties with it. I've been around that stuff before. It doesn't keep the components wet enough imo and users either have to constantly reapply and run the risk of build up or it ends up sticking again. I think it's also worth noting that you may have dented or misaligned something if you got a little too, uh, zealous, with your manual downshifting.
    – Echo_
    Commented Apr 1, 2016 at 1:35
  • But if it was dented or misaligned it wouldn't work fine for a few weeks, then seize up again, and then be fine again when I reapply and work it through again.
    – JackJack Attack
    Commented Apr 1, 2016 at 1:41
  • Might a dent/misalignment exacerbate the sticking when the lube wears off, though? Not saying it's the cause, just saying it may be something to be aware of that's not helping the main issue.
    – Echo_
    Commented Apr 1, 2016 at 1:46
  • This is more than like an issue with the cables being gunked up. Change your cables, or at least pull the inner and flush the outer housing with chain lube, and see if you still have an issue.
    – zenbike
    Commented Apr 2, 2016 at 5:26

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