Hi All,

This is my first post. I have been experiencing a clicking at each rotation of the pulleys at the rear derailleurs, but only when I'm in the 2nd, 3rd and 4th largest cogs. The shifting is smooth and the smaller cogs as well as the largest one are silent. I have cleaned, lubed and checked for a bent rear derailleur using a straight edge. I had a similar clicking noise a couple of years ago and the LBS said my rear derailleur was bent. After they adjusted it, it was fine for a while. I'm pretty careful and I don't think I banged it since then. Like I said, I used a straight edge to check and it looks straight.
The maddening thing is that it's not very loud and a rider next to me can not tell where it's coming from plus it only happens when I'm pedalling. On the work stand there's no noise. I don't have a trainer, so I can't check it that way. The amount of pedal pressure makes no difference as well. No matter how light or hard I'm pedalling in those three gears, it's clickin'! The other gears are silent. Happens in both the big and little rings.
Any ideas would be greatly appreciated.

PS: A couple of years ago a friend replaced the 9 spd Shimano cassette with a 9 spd SRAM. I think the clicking may have started then, but not sure.

Trek Pilot 2.0
105 Shimano 9 spd drivetrain
After Market Compact Double Crankset
Shimano SPD-SL Pedals