First, I'm not a great mechanic, although I take care of a lot of things on my bikes. Any help pointing me in the right direction will be much appreciated.
The complaint is a "clicking" that I can feel and now hear, although it first began as something I could only feel. It only happens when riding the bike, and I cannot duplicate it on a stand. It can happen whether sitting or standing. It does not happen during the entire ride -- only at various times. It seems to be getting more frequent and noticeable. When it happens, it is always at every 2-something pedal revolutions -- never with each pedal revolution -- always 2 or more.
Chainrings are 53t and 39t. Cassette is 12-25. The chain has 1700-1800 miles on it. When noise/feel click occurs, it is most noticeable on cogs 17-25, and more noticeable when on the 39t chainring. The noise/click does change when the chain is put on a different cog. Whereas it might happen precisely every two pedal revolutions on cog 18, it will happen at 2.2 pedal revolutions on cog 19. I do not notice anything in cogs 12-15 on either chainring.
So, I'm thinking with this kind of thing, it must be in the chain somewhere. Otherwise, it would be happening once every pedal revolution or multiple times per pedal revolution. Am I heading in the right direction?
I've checked for stiff links, and if there is one, it isn't readily noticeable. Where the chain was originally joined (by the LBS) was where I assumed I'd find a stiff link. But it is free there. I will look another time tomorrow afternoon when I have a little time to peer at things again.
One thing I'm curious about in reading the Campy chain literature. There is this phrase: "Never remove or modify in any way whatsoever this external link, which is permanently identified by the stamped production batch number, since it has the calibrated holes needed to close the chain." Perhaps I'm not sure what this "batch number" looks like, but I don't see any special number. The only thing I see are all the C11's on the external plates.
What would that "batch number" look like? Is it a series of numbers?
If this special link is missing, might that be causing the problem I'm experiencing? I'm guessing if I'm missing whatever that special link has, maybe it allows something in the chain to shift around and cause the type problems above.
I have checked and adjusted the RD hanger. This fixed minor shifting issues, but did nothing to address the clicking noise.
Sorry for the long post, but I wanted to include anything that might be helpful.