This has puzzled me (and several bike mechanics) for some time. I keep hoping that my bottom bracket will start clicking so I'll know what the problem is, but it's been about two years and I'm sure the BB would have gone by now.

Anyway, the best way to describe the problem is a "crunching" sound -- actually more of a feeling -- with every pedal revolution.

Just some random notes:

1. It's almost as if the Hyperglide chain isn't exactly aligned with the Hyperglide chain rings or cogs and the chain is just missing the teeth. The chain and cassette are brand new, by the way, but this has been going on for a long time.

2. I thought I had found the problem about a year ago in that the inside buckles of my toe clips were catching the crank with each revolution. I removed the toe clips for a while, used straight platform pedals, and the problem went away. Then it came back.

So I'm back on the bike every day now and I'm heading out on a yearly multi-day trip next month, so I want to fix this problem once and for all. More than one bike shop mechanic has told me it's not the bottom bracket, not the pedals, and not the cranks.

Any ideas?