3rd cog noise, please help.

[kalewillis]

Ok so Ive been hearing some noise and been putting it off. So I did some adjustment and cleaned all the debris out of the chain and gears, and it shifts better and it purrs like it's new. But my 3rd cog in the back sounds like it's grinding, and it doesn't matter what chainring I'm in. I don't see any obstruction, and the gears before and after it are all perfect. Also when the wheel spins freely, the cassette wobbles a little bit, is that normal? This is a 2012 caad 10 105. Any input is appreciated

 

[daveryanwyoming]

I'd start by pulling the rear wheel off and seeing if the cassette body wobbles in your hands. If so it's likely that either the lockring is loose or the thin spacer is missing that should be placed between the freehub body and the cassette during installation. It is also possible with some hub designs that the freehub itself is loose and the entire freehub is wobbling. Whatever the cause, take care of any freehub wobble first.

Also check the chain to see if it's worn or 'stretched' from wear. Chains don't literally stretch but the roller bushings wear and the chains elongate. When that happens the chain won't always mesh well with the cogs and that can cause noise. It also slowly wears the cogs and then when you put a fresh chain on the most worn cogs won't mesh well with the new chain so check for chain stretch and if necessary replace the chain. If the chain is badly stretched you may have already worn your most frequently used cogs and they may jump or be noisy with the new chain.

If all that is o.k. then it's likely a small derailleur adjustment as in a small turn of the barrel adjuster to adjust cable tension. If your bike has fallen over or been involved in a crash, even a very low energy crash like tipping over while leaned up against a wall it's possible your derailleur hanger is slightly bent which can make it tough to get clean shifting in all gears.

So a few possibilities, some easier and less expensive to resolve than others but start by investigating the apparent cassette wobble.

-Dave

 

[kalewillis]

Much appreciated Dave, that's good advice, I'll check into it!