I've had an opportunity to try this contraption (or something remarkably similar) and this problem is academic: it's very much unlike a bike, but you'll learn how to stop and dismount without falling off, very quickly (haven't really tried whether I could stop w/o dismount, as I've played with it for a few minutes at most). It's similar to unicycles in this respect (note how in the videos, users ride back and forth a little bit, instead of coming to a complete stop).