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.