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Old 04-15-12, 11:54 AM   #1
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Mystery drivetrain squeak

I've got a hard to locate squeak in the drivetrain of my touring bike. When pedaling under load there is a constant, rapid succession of tiny squeaks. I've also noticed that there seems to be a slight drag. The noise is such that it is very hard to pinpoint while riding. Sounds like a half dozen hamsters running on metal exercise wheels simultaneously, but very soft. Here is what I have found out so far:
  • Noise only occurs under load such as accelerating, uphill or into the wind
  • The noise occurs consistently and constantly under those conditions
  • The noise is only present when pedaling
  • The brakes are properly adjusted and have adequate clearance
  • Both wheels have been serviced and the hubs relubed this spring, no play and they spin freely, no lose spokes and tension fairly equal by ping
  • Cassette and chain have been removed and cleaned, neither is badly worn or damaged
  • No visible damage to chainrings and cranks are tight, noise is a rapid series of fine squeaks rather than the intermittent creak associated with a loose crank
  • With the chain off the crank can be spun freely with no grinding or vibration
  • Pedals are brand new and spin freely by hand without noise, still oozing tiny amount of lubricant at the spindle
  • Bike was in minor endo at low speed earlier this spring but passed inspection by the LBS, chrome moly 1989 Trek 700 frame, has been on the stand and inspected by me several times since and can't find any problems, dropouts are straight and aligned, measurements all equal from one side to the other and lines straight by plumb bob and straight edge
The only thing I haven't done is replace the BB which is a Shimano UN54 that was installed last spring and has about 2200 miles on it. The bike was ridden a lot during the winter including a number of days below zero F and on salted roads in MN but bike was kept clean and well lubed. I have been unable to replicate the noise with the bike on the workstand.

Any other thoughts? Am I missing something?

Last edited by Myosmith; 04-15-12 at 12:00 PM.
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Old 04-15-12, 12:05 PM   #2
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Even harder to guess 2000 miles away.. ride and ignore..
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