Noise From Bottom Bracket

[Seight_Returns]

I have an ’06 Specialized Sirrus hybrid bike that I use for my daily 10 mile round trip commute. It’s developed a creak/click noise that sounds like it’s coming from the bottom bracket that’s driving me mad.

Noise only happens when pedalling hard or climbing and appears to be once per crank rotation.

There’s no perceptible movement of the crank, chainset or bottom bracket. The drive train feels completely smooth, even when the creaking is happening, no other signs that something is wrong except the noise. If I stand alongside the bike with it stationary, put my foot on either pedal and push hard so as to make the frame flex, I hear the noise also.

Here’s what I’ve tried so far, all to no effect:

- Removed and refitted BB cartridge and crankarm/chainset, re-torqueing to spec
- Removed BB cartridge, applied grease and ptfe tape to threads – no effect
- Fitted new BB cartridge – no effect
- Changed pedals and greased pedal thread – no effect
- Verified that the noise still happens with seatpost removed (read somewhere that these noises sometime originate from seatpost)

The only thing that makes a difference is doing the crankarm bolts up really, really tight, far in excess of the recommended torque. If I get them as tight as I can, literally by standing on a 9” allen wrench, it quietened it down for a few miles, but then it came back again. Now no amount of tightening can make it go away.

I can only think of 2 possibilities
- The noise is coming from the frame itself, but I can’t see any cracking around the BB
- The holes in the crankarm and chainset have been damaged by my attempts to overtighten, resulting in them not fitting properly, hence the noise.


Only thing I can think of is to buy a new chainset/crankarm and see if that resolves the problem. Any thoughts before I go to this expense ?

Current BB is a square taper. I have a Trutaviv Powerspline BB of the correct size that I bought by mistake – tempted to try a Powerspline Chainset rather than a square taper one in the hope that it might prevent a recurrence of this problem. Any opinions of Powerspline vs Conventional square taper ?

Any help much appreciated, this is driving me nuts !

Edited by Seight_Returns on Thursday 18th September 17:59

[Parrot of Doom]

Remove the lot, put a bit of wood through the BB hole, and stand on that. See if the frame creaks.

[snotrag]

Chainring bolts... easily missed, often noisy...

[cjs]

Try changing your chain lube! I was using a dry lube, I now use Finish line wet lube.

I had the same problem on my Spec Epic. I had fitted a new Shimano BB, crankset and chain. It ran fine for a week and then had the same symptoms as yours. I was convinced it was the BB and stripped it down and rebuilt, also tried the seat post, noise was still there. On advice I changed the lube on my chain and the noise went, worth a try maybe?

[Seight_Returns]

Found it !

I had a bottle cage attached to the down tube, this was creaking/clicking as the frame flexed under load. Tightening the attachment bolts made the creak but not the click go away. Removing it made all the noise dissapear.

Was driving me mad because the noise was quite loud but I couldn't "feel" anything and felt I'd checked all the the obvious things. Had convinced myself that I had a crack in the frame and was off to Evans at lunchtime to look at new bikes.

Thanks for your help chaps.