Mysterious squeaky sound

Question

I have noticed that my bike makes a high pitched squeaky sound when pedalling on my 12th tooth cassette cog (second smallest), especially when going a bit faster ( over 30 km/h or 18 mph) and applying a bit of torque. The cassette is a Shimano 105 10 speed.

It just happened in that cog. I disassembled the cassette because I noticed it was a bit loose, cleaned it all up, lubed it (with drip lube), same for the chain. After a few tens of kms I noticed that the sound reappeared though much less pronounced and much less frequent.

After another inspection, I noticed that if I rotated hard the cassette it would budge a little, so I decided to tighten much better the cassette and now it appears to not move at all. I do not have a torque wrench so I just did it hard by hand.

The problem now is that I'm back at square 1. The noise has become again very frequent when I pedal at high velocity and applying torque.

I have ridden about 2000 km with this bike (give or take) and the mysterious thing for me it that it happens just at that particular cog (which i would use frequently before). I had the impression that after retightening, maybe the squeak also migrated to the neighboring cogs but I don't think so anymore.

I realise that my comments aren't very precise but I'm quite lost here.

Should I change the chain, because it might be the culprit? Should I change the cassette? Should I grease the cassette using actual grease instead of drip lube?

Thank you very much.

Answer 1

Hmmmm, it sounds like (to me) that you may have a spacer missing behind the cassette on the freehub body for the whole thing to be moving a bit. Also try unscrewing your high limiter screw ever so slightly (about a quarter of a turn) just to see if the noise starts to disappear. (Note, you'll have to change gear and then back in again to get it to deadzone as I call it.)

(I usually call the highest gear a dead-zone gear because there is no force from the cable acting on the derailleur to keep it there, making it rest against the limiter screw.)

It may or may not also be from the derailleur jockey wheels being so far away from the cogs; Has your B-tension screw been set accurately? The tooth of the jockey wheel should be about two millimeters away from the cog when it's on the lowest gear, depending on where you're looking at the reference point. I'd personally reccommend taking it to an LBS if you still can't figure it out; It can take a fair bit of experience to try and diagnose things like this, but if you're not face-to-face with the problem, there's not much that can be gleaned from this. What you perceive as a tapping could be a ticking to me. Or a squeak could be a squeal. It's how each person would personally describe a sound, which is what makes online assistance hard.

If you want to test to see if it's the spacer that's causing the problem as a temporary check method, get a pop bottle, cut it and lay it flat, cut a circle the correct size to fit on the freehub body and test it.

Actually, whlist you're at it, check your rear derailleur hanger; if it's out of whack slightly, it could mean something is rubbing where it wouldn't normally, and may not be to do with the hub at all. (Though, the cassettes moving still does cause concern.)

When reassembling the cassette onto the freehub body, I redidculously highly recommend using Lithium Grease on each component, between where each plastic spacer meets the cogs of the cassette. This grease is very, very light, does not clump as much as others, and is very handy for the fact it's bright white, so you can clean it off of your brake components if ever it flicks, which it shouldn't if you put a thin layer on. :)

Answer 2

Buying a new cassette or freehub body should eliminate the noise. ( With a new cassette comes a new chain too)

But before buying anything, you should check your freehub body for indents in the splines. If there are big indents it's a sign that you should replace the freehub body. If the indents are small, you can try to file them. Check if you have the correct amount of spacers behind the cassette. If a spacer is missing, it's possible that you tighten the lockring, but it won't tighten the cassette.

And last but not least: if do 30km/h on the 12 tooth cog, assuming that you have a double on the front, then you're cross chaining, in the worst possible way, which you should always avoid. The chain tension will be smaller and the chain might rub itself under the rear mech if it's a bit long. In an extreme case, the chain can even rub on the big ring. And also you accelerate wear and lose energy in this case.