Oops, Ran out of time to do a second edit.
Search “coaster” and “freewheel” to start.
They’re called one way clutch bearings.
zxz-bearings.com
eslbearing.com
Someone made a coaster unicycle with these bearings and had it at the last UNICON. I can’t remember who. The problem with this design is that the bearings wear out quickly. The bearings also have max torque loads and unicycling may exceed those torque loads which would explain their short life span in this application.
I think the hub used on the Coker Wheelman might have potential as a hub for a coaster unicycle. You would be able to pedal forwards to gain speed, but backpedaling would do nothing but cause you to coast. I have never seen a Coker Wheelman hub. It may or may not work on a coaster unicycle.
Bryan,
If you’re the guy who restores old cruisers, then I’d like to say that I really admire your work.
cheers… Mojoe
I think it may have been Jack Halpern that had the coaster unicycle with the clutch bearings. I think???
I’ve wondered about designing some kind of a clutch that simply engages or releases the pedals. It would have to be a hand operated clutch. It would allow the hub to freewheel forwards and backwards, or when the clutch was engaged, it would ride like a normal unicycle. It seems like it would be relatively simple, maybe somebody has built something like this, although I’ve never seen or heard of it done.
Nope, Sarah was the one with the coaster uni, now I can’t think what her surmane is Hansen is bugging me,but I’m not certain thats right. I think she posts here sometimes as unipshcogirl or some thing in that vein.
Jack had the coker with the trashed bearings.
Sarah
There were at least two coaster unicycles at UNICON.
Sarah Chastain goes by unipsychogirl here on the forum.
Sarah Chastain had one that’s made from a modified rear coaster hub from a bike. The kind of rear hub that when you backpedal it applies the brake. There is a bit of slop in that setup because you don’t get instantaneous engagement when you start pedaling forwards again.
Someone else had a coaster unicycle made from a modified hub and clutch bearings. I just can’t remember who it was that had that unicycle.
A setup made from the rear hub of a BMX bike or singlespeed MTB might work. You’d want to start with a hub that gets very quick engagement as soon as you start pedaling forwards. You’d also have to figure out how to fit a pedal spindle in the hub. I’m not sure how big of a diameter of a spindle you could fit in a BMX hub. You might have to use a skinny spindle which would affect the strength. If it was easy I’m sure someone would have done it by now.
Thanks for the info guys…
I’m looking to create a bike? similar to the coker wheelman but a slacker more custom design with a 24 or 26 front wheel and a 20" rear wheel…I’m not looking for it to have a brake just have the capability to coast…i would have rim brakes like the coker.
mojoe…yeah that’s me…thanks for checking out my work
bryan
Re: Thanks for the info guys…
We can get off on a tangent here on the forum sometimes. 
The homebrew coaster hubs have not worked well.
The hub from the Coker Wheelman is probably the best option. Contact Unicycle.com and see if they can get the hub. Unicycle.com rebuilt a bunch of used Coker wheels from the Coker Wheelman and the Coker Monster Bike. Maybe they still have some of the Wheelman hubs. See Unicycle.com’s product description for their Remanufactured Coker wheel
I have no idea about the quality of the Wheelman hub.
There are probably some other coaster hub options. Razor makes a Big Wheel replica (yeah, like the Mattel Big Wheel) that has a coaster hub. There may be some other adult sized tricycles with coaster hubs on the front wheel.
i am reviving this thread because i want somebody to post a pic of a coasting uni
Buy Training Wheel Not Required. The one I made, which was really primitive, is featured in it. I think Kyle Grasso rides it.
I also made a video of me riding it a while ago, but I can’t find it in the gallery.
Make it even more exciting by adapting a Rolhoff 14-speed hub to driving through the axle to the sprocket drive…
http://www.rohloff.de/en/products/speedhub/index.html
Rather a freecoaster hub, that still are expensive, but not that expensive as before.
As the purpose is coasting, you wont have to deal with the nasty part of shifting a geared hub like the called Schlumpf hub (named after the producer, not the engineer who I witnessed to be the one who came up with the idea and 1st sketch in precence of Mr. Schlumpf -who denied that it was possible that entire day-).
Do not buy the razor big wheel (tricycle kids big wheel) for the hub. I am building a downhill?off road bigwheel and am trying to figure out something different. The hub that is on it is cheap plastic and will not last. Check this out. http://www.unicycle.uk.com/coker-wheelman-penny-farthing-hub-3.html
I just found some Polish bike prototype. It seems to have hub drive like trikes and has 3 gears in it:
I’m wondering if it could be adapted to freewheel unicycle.
That bike looks whacky I definately want a 3-geared freewheeling 29er uni though 
It’s hard to see detailed information but it looks there is a custom method to attach the fork to the hub which may be along the lines of this 3.8x geared drift drift trike that is not quite for sale yet. I like that there are three shiftable gears but it needs a disc brake to be an effective freewheel unicycle. I also would prefer a smaller wheel for mountain unicycling since I’m on the short side.
We’ll see. Not even the gear ratios are stated, so not much is known. I contacted the company if a hub or front wheel will be available separately.
This seems to be a similar design from Korean company Bygen:
Since both designs are folding bikes it might be possible to convert them to freewheel unicycles by detaching the extra frame sections.
Those pedal lever thingys (Crank arms…?) confuse me… How do they stay horizontal? 
Surely there’s a lot of play in them, even if they’re ratcheted to only spin in one direction. Maybe I’m missing something here but they just look so unnatural! 
Cool tech though. Folding bikes are great, and the direct drive ones seem even more portable, so it’s good that the tech to make them go faster is starting to come round (Especially so us Uni riders potentially benefit)