Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 8 Post(s)
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A common cause of this is one pedal being just a hair loose on the crank arm, possibly with dirt under the face. It takes a minute to remove, clean the threads and face, grease and remount.
The other easy cause is loose chainring bolts allowing the chainrings to shift a hair under load. use the hex or Torx key and give each bolt a tug and see of ti moves.
If either of the above cures it, you've dodged a ton of PIA diagnostics because everthing else is more complicated, Starting with loose crank/spindle fit, loose BB, spindle play in External BB bearings, BB unit or bearings moving in the BB shell, dry chain, creaking as it settles on the chainring (common with worn chainrings), or any number of things having nothing to do with the BB, including rear hub axle face moving in the dropout, saddle/rails/post, and on and on.
Start with the simple, and use some diagnostics based on timing, frequency, and any other factors which might yield a hint, before you start taking everything apart.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
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