registered usar

I'm adjusting my derailleur right now. So far I got it to shift into every gear with just one click so the indexing works just fine. Now I'm fining tuning. What gear combinations are supposed to rub (considered normal?) ? Right now when I'm in the largest diameter chainring and the smallest diameter cog I get some very light mechanical rubbing noise. I want to adjust everything up to spec but don't know which gear extremities (for cog/chainring) will make some noise. This is the only real area of maintenance that I'm having trouble with. The noise is driving me crazy.

Bill Kapaun

I'm not sure "supposed to rub" is quite the correct term.

You aren't supposed to use the combinations that cause the chain to run at a "severe" angle.
Big-Big & Small-Small.

"Right now when I'm in the largest diameter chainring and the smallest diameter cog I get some very light mechanical rubbing noise."
That combo shouldn't rub.
You should be able to use the ABSOLUTE lowest and highest gear combos without a rub.

chephy

Your chain is rubbing the front derailleur. The large-large and small-small combo are the only ones in which it is acceptable to have some noise (not desirable). The large-small combo should be silent for sure. To fix this you need to adjust the cable tension on the front derailleur. There should be an adjustment barrel by the shifter. Turn it counterclockwise in quarter-turn increments or so until the noise is gone. Don't turn it further than that or you'll mess up front shifting.

You may also have to adjust derailleur delimiter screws to allow the front derailleur to travel as far enough as it has to go to avoid rubbing. To check whether that needs to be done, try pulling the front derailleur away from the bike as far as it'll go and see if that creates sufficient clearance between it and the chain in the large-small combo. If it does, you should be ok.

doctortalk121

xxx

registered usar

Ok, so if I take it to a bike shop and have them tune it up and it still makes noise on certain gear combinations that is normal? I kind of thought a perfectly adjusted bike would be silent except for the faint ever present chain noise as it moves while pedalling.

Tapeworm21

Sometimes you can get it to be rub free. BUT, don't be so picky. Those gears that rub... you're not supposed to be putting that much stress on the chain.... so don't even use them, rub or no rub. If you're using a compact double, forget about it. You're going to get rub in the cross chain. It's the bikes way of saying, "OOOOWWWWWWW!"

chephy

Sometimes you'll have to settle for rub in unadvisable combos (such as 3-1 and 1-8 on a 24-speed bike). But the other gears, in particular the large chainring - small cog and small chainring - large cog combos (3-8 and 1-1), must be completely silent. Rubbing noise there is unacceptable. If you can't adjust the derailleur so as to avoid it, you might have problems with your bike (e.g. bent chainring).

If you read the first post, you'll notice that the OP is not talking about chain rub in cross-chaining combinations. He's talking about chain rub in the highest possible gear on the bike which is completely unacceptable.