Originally Posted by
Ranko Kohime
....Looking at the crank from the right side, this occurs between 6-9 o'clock, and only when high torque is applied to the pedals. And I feel it through the right pedal only, not the left (despite the torque coming from the left side at that part of the revolution).....BB is solid, no slop that I can make out.....
i'd bet it's the bearings in (one of) your pedals. hold the crank steady and try to wiggle the
body of each pedal in turn. one of them will have some play. if you remove the pedals, hold
the cage and try to wiggle the spindle, the play will be more obvious.