i made one with a caliper brake from a bike.the cable was to short.my wheels would skid and were down fast. and there was no room for my feet.it sucked ballz
That's dumb, extra weight and more of a hassle all for little or no point.
Jonah, two or three wheels would be pretty pointless too, because they would only be on the ground if you were riding perfectly straight, if you leaned the slightest bit you would be on one wheel again.