Quote: the "known fact" issue is exactly what started this thread. Everyone says it but no one has offered any real evidence other than saying that it is a "known fact".
All the major motorcycle manufacturers switched from using ball bearings in the steering head (the part of the the frame where the front suspension is mounted) to tapered roller bearings because the ball bearings would consistently develop a "notch" in the normal range of steering motion, typically right in the center where most loads occured.
Ball bearings are bicycle-grade technology. There's no way I'd run 'em in any axle application where they'd be expected to deal w/ significant side loads.
