If you're bouncing at 85rpm, that makes me wonder if your saddle is too low. Like crazycanuck, I can spin over 100rpm before my hips begin to bounce. If your leg isn't stretched out enough at the bottom of the pedal stroke, then there'd definitely be an upward push on the hips at the top of the stroke even at lower cadences (Does that make sense?). Do you have an LBS that could check your fit?