You can get a green machine at toys r us. I was going to make a coaster uni a long time ago but never got around to it, I did make a BCuni though.
That would be sweet for street and skate park style. Imange you could clear so many stairs 
and grinding would be easier to.
Great shot
Buy Brian Mackenzie’s “Training Wheel Not Required”
He has great video of it.
Adam
Instead of paying $80 for a Green Machine (like stupid ol’ me), just copy down the serial # off the one on display at Toys R Us (it’s stamped onto the bottom of the frame). Then call Huffy and ask for a replacement wheel. They’ll ask for the serial # as proof of purchase. I think it’s around $25 and should include complete wheelset with tire and cranks.
However…I don’t think the GM hub is made to handle the forces of an adult unicyclist. Mine began slipping after a few hours of practice, like maybe the teeth or whatever inside the hub started breaking off, until it simply freewheeled in both directions, making the cranks useless (unless you put them on kangaroo style and make it a BC wheel as I assume Skippii has done[glad you found a use for it]). I haven’t bought a replacement yet, but good luck if you go this route, and let us know if yours breaks too, mine might have just been faulty.
take it to a skate park. just cus it would be fun to watch someone spine on a uni
I dunno, mine hasn’t started slipping yet, and I took it through some pretty bad falls. I weigh 240 lbs, so I don’t think it was the weight. Maybe they just sent you a bad one.
I have 2, the best of which cost me almost nothing. It is a 16" wheel one that I found in a skip! It is the front wheel of one of those trike things that was trendie a few years ago. I just slotted the steerer put a seatclamp on it and a seatpost/seat and it was there.
They are not that hard to ride, great fun as well.
It is North who has the Coker wheelman one.
Roger
There’s a Green Machine on ebay at the moment if anyone’s interested -
http://cgi.ebay.co.uk/GREEN-MACHINE_W0QQitemZ7209226385QQcategoryZ72570QQrdZ1QQcmdZViewItem
It’s collection only North Yorkshire, and I’m broke anyway, so I won’t be bidding, but I’ll be keeping an eye out for tricycles in skips. It sounds a reasonably simple conversion even for someone who failed tech GSCE… And I’d love to have one, it was seriously good fun trying Roger’s in Perth, although you definitely meet the floor a lot faster than off a normal unicycle.
This is not the best type to go for, the one I found had handlebars so the forks worked as a frame.
Roger
Yeah, I had to get a 20" nimbus frame and widen the fork a bit to make it fit. The bearings are tiny but have plastic casings over them that with fit in standard uni main-caps. The GM has a 20" wheel.
If by skip you mean dumpster, then I believe that’s exactly how Digitalattrition came by his too, with the same handlebar fork thing.
would it be possible to convert a bike hub to a free wheel unicycle hub, or a unicycle hub into a free wheel?
The bike hub would have the problem of being built to get driver from only one side, and the axle is stationary, and the unicycle hub has the problem of being a fully rigid one piece unit.
It would be very hard to convert something like a hub to do a very different job, such as the free wheel unicycle.
I think that is why the trike wheel does the job so well.
I have a uni with freewheel 
That solves the hub problem though doesn’t it? 
I have no problems with it.
Here it is, my “killer”
thats a beast.
Mike
I kno that the S.W.A.T team made one…
jeeesus, can you ride that? i seriously can’t even imagine riding it, you’d be in such a weird position and everything.
I had a dream last night that I was riding something like that “killer”. It was made from a mountainbike and it was yellow. Some guy was riding it around a grassy field and asked if I wanted to try it (he didnt know that I could ride a unicycle). So I got onto it and started riding down the field. The dream was so realistic that when I stopped pedaling and the wheel started freewheeling, I could feel the wind in my face and the dew from the grass being kicked up onto my legs. I hopped off the moutainbike-turned-unicycle, turned around, and saw a really tall giraffe with two sets of pedals; one set around 6ft and one around 12ft.
That wasnt my first dream about coasting on a unicycle either…
I still can’t coast more than 2ft though
yes I can ride it.