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Rear derailleur touching spokes(8 posts)

Rear derailleur touching spokescxr600
Jan 6, 2004 3:33 AM
My rear derailleur is touching spokes when under power in the bottom gear.
The bike did this from new but I got round the problem by adjusting the limit screw on the dreailleur and pulling the wheel over with spoke tension.
After having the rear wheel trued and a couple of spokes replaced, the problem has returned.
I dont think I can center the wheel in both the chain stays and the seat stays, and also have spoke clearence for the derailleur.
Im now thinking of making do with a washer as a spacer on the drive side of the axel, but would like to know what the proper fix would be.
Spacer inside the cassette? This is all very weird,Spunout
Jan 6, 2004 4:16 AM
I think you should have a look over by a better mechanic. If the wheel is in good shape, the derailleur or dropout might be bent.

Or, drive side spokes may be laced incorrectly such that they poke out too much.
re: Rear derailleur touching spokesWoof the dog
Jan 6, 2004 7:03 AM
mmm, it actually happened to me too, it was barely rubbing on the spokes when riding 23/39 up a steep incline and rocking a bike some. It is not THAT uncommon (my secret feeling is that a lot more bikes do it than people think). You can adjust the limit screw to the limit where you still have an ok shifting. But it seems that what determines whether your der rubs is the cog you use. With 25 or 27, there is no rub on my bike, as the der is lower and away from the spokes. Also, it depends on how flexy is the wheel. Since rim strength is important for laterally stiff wheels, a flimsy rim will flex more and cause a rub like yours, I think.

If it really rubs, then there is something wrong, but getting a spacer is just stupid, I don't even understand how it would work... does that mean your lockring won't be in fully? that's just creating more problems.

woof.
re: Rear derailleur touching spokescxr600
Jan 6, 2004 8:17 AM
The spacer idea wasnt for the freehub but the axel. Like an additional washer on the cone or similar.
This would splay the frame out slightly at the dropout and maybe give a bit more derailleur clearence to the spokes.
I could bend out the hanger (which is not damaged), but this just does the same thing as adjusting the limit screw and thats allready set so that the bike only just makes it to the largest sprocket. The wheel is built correctly, if I move the wheel over using spoke tension to give more spoke clearence for the derailleur, then I dont think I can have the rim centered between both chain stays and seat stays. When I tried this when I first got the bike, I think it resulted in an unbalanced wheel - hence the 2 snapped spokes when the bike was sitting in the house.
I dont think there is actually anything wrong with the bike, frame or otherwise, I just think there is insuficient clearence which is noticable when the bike flexes.
re: Rear derailleur touching spokesWoof the dog
Jan 6, 2004 11:11 AM
so you said your hanger is not damaged. are you sure? its not hard to push it in without noticing.

woof.
You need to find a competent mechanic.Spoke Wrench
Jan 6, 2004 3:15 PM
Dropout alignment problems are common. Adjusting the dropout IS NOT the same as adjusting the limit screw. Adjusting the dropout changes the angle of the derailleur from the vertical. Frankly, I suspect that's your problem.

Everybody wants to screw around with spacers and limit screws. If the baseline isn't right, that isn't going to fix it. All those adjustments do is add one more problem for the mechanic to solve. A bicycle is a simple machine. It's amasing how many mechanical problems go away when you start with the basics and systematically make sure each part is right. The more "shade tree mechanics" who have fooled with the bike, the longer it takes to find and solve all the problems.
First, check the default settings.Spoke Wrench
Jan 6, 2004 8:29 AM
1. Check the rear wheel for trueness and dish.
2. Check the dropout for trueness.
3. Start at the very beginning and check your derailleur adjustment.

This is a problem that I have encountered several times and, in every single case, one of the above solved the problem. It's important to do them in order because you use the wheel to check the dropout alignment and if the dropout is wrong the derailleur adjustment can't be right.
I'd put a spacer between the cassette and freehub.dzrider
Jan 6, 2004 11:44 AM
Also look to see that the screw holding the upper pulley isn't sticking out the back.