Front derailleur won't spring back to lower gears

Question

The front derailleur on my mountainbike sometimes gets stuck in high gears. When this happens and I want to shift down I can nudge it a bit with my foot and it will spring back to the lower gear.

I think the spring is still strong enough because just a small nudge is enough. I haven't been fiddling with the two adjuster screws, and -as I said- if I nudge the derailleur after shifting it jumps to the correct position. The issue seems to be the (admittedly pretty large) amount of gunk that has gotten stuck in the derailleur over the years. I tried applying some WD-40 to the moving parts but two small applications have not really helped remove the gunk. Is this still the way to go or is there a better way to get the gunk out without completely removing the derailleur (which I -for now- am too lazy to do).

This question deals with a similar problem, but it hasn't moved beyond the diagnosis part (which I have already done I think).

[update:]

I tried liberally applying WD-40 a few times over the course of a week, including some (aided by hand on the derailleur) shifting after each application. This mostly removed the issue when shifting from 3 to 2, but 2 to 1 remained. Today I went to my local car-cleaning station and applied a high-pressure hose to the derailleur. This removed all the visible gunk. I applied some oil, now shifting is as smooth as can be given the state of my chain and chainrings.

Answer 1

If you believe you have diagnosed the problem then a clean and a service should be all that is required. You don't have to remove the FD.

WD-40 will not displace mud effectively. I would:

• use a hose with a decent amount of pressure to remove the gunk, wait for it to dry. (be careful not to spray around the bottom bracket)

• apply WD-40 to any moving parts on the derailleur but focus on the pivot points to remove old lube.

• once the WD-40 has evaporated apply some decent chain lube to the pivots.

If this doesn't fix the problem and the cable is moving freely the derailleur may be bent or the spring has lost the required tension.

Answer 2

I would clean the derailleur but also replace the shifter cables and housing. In my experience, it is much more likely for the cables to be a little bit stuck than the actual derailleur itself.

Answer 3

I had exactly the same problem last year due to running into snowy roads for a week or two. The front derailleur clutch jammed. DO the following:

1. Put your gears to 1:1 position. This is the safest position to start with the optimum cable tension. Also, you will have less chances of messing things up.

2. loosen the joint that is holding the derailleur cable for the front derailleur clutch. This is actually located near where your cassettes are (gear coggs).

3. Clean the clutch joints and housings properly. If you have a thin-brissled brush, it is good. Otherwise, use a cleaning cloth.

4. Clean as thoroughly as possible and make sure all the debris and small granules are not blocking any of the intersections/joints.

5. Tighten the cable back in the joint, ideally and exactly where it was before.

6. Check the up/down shifts for all the gear to ensure that you have got the correct tension level.

FUTURE REFERENCE: Depending on how heavy your ride schedule is, you should do it ideally every 4 months or so. In this way, you keep your bike in good condition as well as the safety. You don't want to be in the middle of the traffic and bashing your head wondering why your gear is not shifting down :p

I hope this helps.