"Modeled on a 1924 circus design," reports Melissa Wagenberg Lasher for Popular Mechanics,
the Monowheel works like a ball bearing: Anchored by the weight of the engine and driver, the inner wheel stays upright while the outer loop, propelled by a 90cc engine, revolves at 20 mph or more. "It's unstable, steering is virtually impossible, your vision is obscured while you're riding, and if you brake too fast you gerbil over," flipping heels over helmet, says David Southall of the contraption he calls the Red Max. "But it was 100 percent worth building."
Any resemblance to another innovative uni-wheel motorized vehicle design, I suppose, is purely coincidental.
Photo Credits: George Lange/Popular Mechanics, South Park