I just replaced my chain, cassette and rear derailleur on my bike. I adjusted the H and L screws, the B screw and the indexing. It works great on the stand or just spinning along. When I apply a little power, it sounds 'crunchy' at the bottom of the derailleur when the chain passes near the lower pulley. I also checked the chain for stiff links and found none. The derailleur lines up perfectly with the cogs it seems, and the alignment of the RD hanger looks straight to me...it's an 8 speed drivetrain with old Ultegra 600 brifters up front and an SRAM cassette out back with a Deore longcage RD...What am I missing here?