I think it is not as simple because the belts require a lot more chain tension. This is difficult if you don't have the dropouts for it. Somehow, you have to tension it just right, then tighten the rear axle and ensure the rear wheel is pointing the right direction. The proper dropouts are like motorcycle dropouts. You loosen the bolts, turn the screws until you get enough tension, then you tighten the bolts. This arrangement is not available on the Rad.
Also, this can stress out rear axle bearings not designed to take this constant tension (the pulling of the belt). On a Rad, the bearing/ bearing races are not replaceable so when the bearing goes, the motor is useless.