New monocycle/unicycle working design; it's also motorized!

Popular Science | Reinventing the Wheel:,12543,611352,00.html


Ken Fuchs <>

Re: New monocycle/unicycle working design; it’s also motorized!

This monocycle was mentioned on slashdot yesterday. The slashdot article is here. The builder has a web page here.

My question. Is it a monocycle if the rider is not riding inside the wheel? It looks more like a sideways unicycle to me.

How did I NOT see that at burning man.

BTW. Anybody from here going this year?

Looks like it needs some sort of skids or wheels for when the front part hits the ground, and also some sort of roll cage. Sticking those frame points into the ground at 57mph could ruin your whole day.

I think it would be cool to put the rider behind that monster wheel in some sort of teardrop fairing. Not sure how that would affect steering, but it would make hops and drops a whole lot easier to take. Sort of a minimalist SUV.

My question. Is it a monocycle if the rider is not riding inside the wheel? It looks more like a sideways unicycle to me.

My understanding is that a monocycle carries the rider inside the wheel, and a unicycle has the rider outside the wheel. Maybe “monowheel” is a generic term to cover both types? I would probably call this thing a motorized recumbent unicycle. Hard braking is possible because the frame is shaped to skid along the ground; I would consider adding a small nosewheel underneath there, and the roll cage is definitely a good idea. It apparently relies on a gyroscope for steering control, so a gyro failure at highway speed could result in a pretty spectacular UPD (the D being Destruction, Disaster, Devastation)…

When the Bombadeer uni came out I had a long converstation with an Italian engineer friend of mine who specializes in reliability and safey engineering. (He’s also an accomplished motorcycle affectionado and was a mechanic in the rally circuits.)

We both agreed that any form of high-speed motorized/gyro stabilized unicycle would requre all the fault-tolerance tricks of the trade (low failure rate parts, high redundancy, mechanic certification, maintenance logs, system certifications, etc) used in aerospace and nuclear engineering.

I was surprised to hear that these things were already required on high performance road motorcycles. Apparently if the engine or brake controls fritz out on any modern crotch rocket you’re in for a world of hurt. That said, I do think the single-wheel machines are more dangerous. The contact patch is a single-point failure that no amount of engineering will fix. Hit a bump wrong and you’re toast.

Re: Re: New monocycle/unicycle working design; it’s also motorized!

Though the rider is not inside the wheel, it uses the same technique as a “classic” monocycle to stay upright, that of a large amount of weight moving in relation to the hub. Since the mass that keeps the frame upright is based inside the wheel, I think calling it a monocycle is not inaccurate.

I don’t think of it as a unicycle because it’s not human-driven. I realize a motorcycle isn’t either, but at least on a motorcycle the rider seems to be the main control for balance. On this 1100 pound beast, the rider has input but the mechanism (and counterweighting) seems to do most of the work.

The Bombardier hasn’t really “come out,” it’s just a design concept. Like you said, to have any degree of safety with such a thing, you’d have to have lots of precision parts, redundant controls, and still some amount of risk of a very catastrophic failure.

Bombardier does however make airplanes and railway carriages. They definitely seem to know what they’re doing.