Noise/sensation has me stumped
 

A bike that I ride infrequently is perplexing me. It is a Columbus Zonal framed road bike that I built up with Campy Xenon 10 Compact components about 8 years ago. It has what feels like a slight slippage at the pedals and a slight knocking sound (I don't wear my hearing aids when I ride so the sound might be louder than I think). This occurs occasionally in or out of the saddle as my pedaling revolution reaches 2 o'clock on the right and less frequently at 10 o'clock on the left when I am putting more power into the drive train.

It is a sound and sensation that I've associated in the past with worn Speedplay X cleats, and those cleats were worn so I put new cleats on that pair of shoes. Didn't help. I switched the pedals with those from a bike that doesn't have this problem. Didn't help. I tried a different pair of shoes. No help. Thought perhaps the free-hub or cassette was hincky, so I switched the rear wheel and cassette with another bike. No help. Retorqued the crankset on the AC-H square taper sealed cartridge BB, retorqued the chainring bolts. Didn't help. Removed the BB, greased the threads and retorqued it. Didn't help. The square tapers in the crankset look okay and the crankset has never been ridden loose. Inspected the frame. No visible cracks. Thought I might detect a bit of play in the BB although it turns smooth so I ordered and installed a used Token BB from eBay (saved 100 grams!) Still have the same problem.

I have a NOS Veloce Ultra-torque BB/crankset on the way from Taiwan and will order cups but have no reason to believe this will fix the problem. I theorized at one point that I might have a hitch in my pedaling that only becomes apparent when riding the compact crank and allows the freehub pawls to get a bit ahead of the hub ratchets making the noise and sensation occur when the ratchets are re-engaging, but it has the problem (less frequently) in the 50 tooth chainring and in some of the lower cogs as well as in the lowest gear configuration. The Veloce UN-10 chain probably has fewer than 500 miles on it and was installed with a new quick-link.

Any suggestions? Ride it until something really breaks? Possibly on that 60 mile charity ride in the foothills with my older brotherZ:notamused:

have you check your seat rails ? loosen the clamp and add a little grease to the rails and tighten clamp back down . frames can carry sounds from others parts . if you replace the BB and the problem is still there , I would start checking other places .

Thanks. I will give it a shot, but it happens when I'm out of the saddle. BTY another thing I tried was standing and reverse pedaling to see if there was any movement between the two cranks. Nothing.

Instead of grease ,try plumper 's tape on the treads of the seal BB . Try replacing the left crank arm , maybe the hole the axle goes into been enlarge , I know most will tell you not to put grease on the BB 's axle where the crank go , but try it anyway , it wouldn't hurt anything plus it might quite the noise . It might just be flexing of the frame ,but if it was you would notice that before now .