Sorry to just barge in with this, I've never posted in this section before, but I've had a mysterious noise coming from my road bike that's beginning to drive me nuts.
It sounds, and feels, a little like when it's shifting- except I'm not shifting, and it doesn't actually change gears, it just makes that sound like when the chain clicks into place. It's rare that I hear it- I might hear it an average of once every time I ride the bike- and doesn't occur with any consistent pattern, so it's hard to reproduce it for a bike mechanic to evaluate.
The bike is 17 years old with 8sp Campy index shifting. My first thought was that it might be the bottom bracket or a crack in the frame or the crank or something, but they all seem to check out when I look them over. It just came to me that it might be the rear derailleur- maybe a stuck pulley or something that's catching on the chain? Any other ideas?