Comment by corin_

It's not that people can't stand on one foot, it's that if you stand on this wheel with only one foot, then you'll fall sideways before your other foot has a chance to hit the ground. Well, that's my assumption, anyway. Get on a (normal) bike, ride along, then stand up on it so your weight is on the pedals through your feet. Come to a stop, then try and get off it, from standing, without supporting yourself with handlebars or seat.