That’s depends upon your definition of plenty. I have yet to see someone commuting on one so I’d say there is still a serious shortage!
I did think that just after I’d posted - perhaps not quite the right word! What I meant is that various versions of the monocycle concept have been produced, but they’re not exactly common…
Rob
The most interesting thing I see in that prototype photo is Schwalbe Marathon tyres, three of them, combined to make a large pneumatic tyre. No indication of whether it really works, or is smooth enough to work well, but intriguing nonetheless. I’ve emailed the maker for more info.
If we could have a 36" tyre with the weight of a bike hybrid tyre like a Marathon it would be wonderful.
Sam
Standing up on the pedals is the way to introduce suspension to a unicycle.
My Hoopcycle unicycle
Hi everyone,
I think I have something original here that I made.
Hubless?? sort of.
It sort of fits this thread, well at least its not a bicycle. It has one wheel if you don’t count the 2 rollers.
I call it a Hoopcycle. Is there a better name?
As it is now it is just for show, meaning it is slow, vibrates like mad, hard to ride, too heavy etc.
But very interesting.
I will be at the Laguna Niguel parade tomorrow dec 11, 2010, riding this.
Now I will spend more time to made it parade reliable.
Later I can post video or specs etc if there is interest.
parade info
Mark
Nice design! The effective gear is that of the smaller wheel, right?
You clever guys always amaze me. I never thought there would be so many configurations of a unicycle, and now another. That hoopcycle is neat.
curbrider: Very cool! Yes that looks similar to the idea of this thread, thanks for sharing.
More information and a video would be much appreciated. For example I’m interested in how you built the wheel, and how the “gearing” works. From the picture it looks like the small wheel drives the large wheel by friction, much like a two-wheeled giraffe.
What’s the top wheel for? It looks like it’s there to keep the big wheel from oscillating front-to-back? A fascinating idea.
Can you put down the Barbie camera and borrow a “real” one for another photo? 
I looks like the effective wheel size would be the distance from the hub to the ground, but it has the ride-over abilities of a larger wheel. How large is the drive wheel?
How does it ride? It looks like an interesting idea.
Scott
I agree with tholub - the gearing would be the same as if just riding the small wheel on its own, but along a rolling 2" thick (or however thick the big tyre and rim is) platform. It would probably be a bit less prone to “tripping” over small bumps as a normal tiny-wheeled unicycle, but gearing would be the same.
Looks interesting though, which is presumably the builder’s main intention.
Rob