My road bike is set up with Campagnolo Centaur 3 X 10. Recently it started making noise as if the rear derailleur was not adjusted correctly. The noice would only occur in about three of the cassette cogs in the middle of the cassette. The noise only occurs when I am pushing hard, so I have not been able to duplicate it while the bike is on the repair stand.
I replaced the chain. The noise continued. I replaced the cassette and the noise continued. It happens on both the the large and small chainring. I am totally bumfuzzled.