Took the Rockhopper into the LBS for its (slightly overdue, erm) Free First Service last week.

Since then, and probably completely coincidentally, I've picked up a squeak. It sounds like the squeal you get from disc brakes, only not quite as severe, and does it on the downstroke of the drivetrain-side crank when under heavy load; ie, it's fine 90% of the time, just does it when I'm out of the seat pumping in too high a gear.

Any ideas?

My money's on BB threads just needing a good greasing.
Take out the BB; liberal application of grease to threads; re-fit.

That was my first thought but, they're Hollowtech II bearings… I'm still feeling my way with modern bike mechanics, but aren't they sealed units?

I may be being dumb but the threads of the BB should not be moving as the should be done up tight. I can see the bearing being the issue as this moves but not the threads.

Seeing as it is since the shop I would run it back to them and ask them find it for you. If you start to go and find it you may get a warranty issue when you do find it.

Try threads on chainring bolt and pedals – greased and tight.

It's worth checking your pedal bearings and that your shoe doesn't rub the crank when you're giving it the berries.

That was my first thought but, they're Hollowtech II bearings… I'm still feeling my way with modern bike mechanics, but aren't they sealed units?

Yes they are but they do not last for ever and will last even less if you keep jet washing and hosing them down. Water gets in and the bearings will rust and wear out. Mind you I would not expect this to happen by the first 6 week service unless it had been abused or not set up correctly from day one. There is a pre-load that you apply to the bearings before doing up the cranks. If you over do this the life of the BB will be greatly reduced. How overdue was it for the free service?

I can see the bearing being the issue as this moves but not the threads.

Do you have experience of what creates noises on bikes?

…and that your shoe doesn't rub the crank when you're giving it the berries

exactly what I was going to say ! happens to me on occassions.

Yep, I have chased down may a creak and squeak on my various bikes.

Ah. Your experience is different to mine (monkey wrench for way too long).

Seeing as it is since the shop I would run it back to them and ask them find it for you.

That might not be a bad idea TBH, I'm back there at the weekend for a warranty job on the OH's bike.

Try threads on chainring bolt and pedals – greased and tight.

Aha, pedals. The pedals that I replaced a while back. Good point, well made.

Yes they are but they do not last for ever and will last even less if you keep jet washing and hosing them down.

… ah. Are they user-servicable, or is it a case of "buy new ones and be more careful"?

How overdue was it for the free service?

Bought just after easter, so quite a while; didn't use the bikes for a bit when they were new due to injury and there didn't seem to be much point in returning virgin bikes, then after that it just slipped my mind. I've done about 200 miles on it.

…and that your shoe doesn't rub the crank when you're giving it the berries

Definitely not the shoes, wrong kind of noise apart from anything else. It sounds like the front disc brake, I'm still not wholly convinced that it isn't other than I can't come up with a train of logic that would explain that.

I think, after a scoot out tonight and a lot of hmmmmming with my head at funny angles, that it's actually my rear brake. God only knows why it's doing it under load, but I'll clean off the rotor and see if it shuts up.

Cheers all for the feedback, appreciated.

Was gonna say the brake, I had the same thing with my front a while ago, it could be the rotors warped it should stop after a bit.

Anyone know why my 20mm bolt thru hope is making an odd creaking noise, a bit like creaking metal?

a pipe bomb!!! hooray! (points available for finding the reference)

…and sometimes it's the quick-release skewers (worth a re-tighten)