I've searched these forums, Sheldon Brown's forums, and visited my LBS but cannot unravel this mystery.
Normally, my drivetrain is virtually silent -- I avoid cross-chaining, re-lube with wet and wipe down my chain after almost every ride, and keep derailler adjustments dialed in. However, occasionally when climbing at low cadence in my largest cluster gear (28 tooth), I will hear a squeaky "chattering" or shuddering sound. I have a triple chainring, and the sound can occur when I'm on my smallest or middle front gear.
The chain is not rubbing the front derailler. The sound does not have a "clicking" component. It sounds squeaky, almost like fingernails on a chalkboard. If you've ever heard a cat chatter when stalking a bird, that's the sound. The chattering frequency is higher than my pedaling cadence. It stops when I stop pedaling. I can't feel the sound in my feet.
I can't repeat the sound on the stand or at the LBS -- it just comes up on long climbs.
My equipment is:
- 2008 Specialized Roubaix Elite Triple, appoximately 10,000 miles -- I am second owner
- 11/28 Ultregra 10 speed rear cluster -- replaced with last chain
- DuraAce 10 speed triple chain - between .50 and .75 of stretch (closer to .5)
- Gossamer FSA crank and triple chainrings - never replaced
- Gossamer FSA MegaExo bottom bracket - never replaced
I'm thinking the bottom bracket bearings my be starting to age -- it sounds like lack of lubrication.
Any advice is must appreciated!