[Rick TYler]

I was interested in hearing your distance numbers. We tried and gave up on that design because we couldn't get the range we wanted. We hypothesized that a lot of energy was being used in deforming the ball as it went around the curve. It didn't do really badly, just a little worse than a couple of other wheel styles we tried. (And it did better than our belt drive approach which we abandoned mostly for packaging reasons.) Good luck!