I posted this on an old bicycle site and was steered to this site. I wondered if anyone could help me figure out who the manufacturer was and maybe about the time frame of this unicycle frame Thanks in advance
I’m no expert (there aren’t any), but it looks homemade or custom. The seat post clamp is unique. The bearing holders are better than most factory frames from the 60’s or 70’s. I’ll defer to johnfoss, who knows more than anyone should about unicycle history. You might have more success dating the seat.
That frame is COOL! I’ve never seen one like it. Very interesting, and I am definitely leaning toward handmade. By a real craftsman. Do you think it’s steel, aluminum or something else? What’s the history of that uni that you are aware of? In other words, how (and where) did you come to acquire it?
It’s probably an optical illusion, but the bearing holes look like they’re oval. If they are, that would be really, really weird. What’s the intended wheel size or distance from axle to inside top of fork crown?
I have seen some aluminum frames that are from the 1940s or 50s, which I was told were made by Nissen, a company that still makes gymnastics equipment like trampolines, balance beams and such. But this one is different.
It is cast brass and nickel or chrome plated. The seat post clamp is a steel insert in the brass casting. The axle holes are round. It has a Messenger seat. I bought it years ago as is, at a bike meet, maybe Portland. I am pretty sure it takes a 24" wheel I am not sure it had bearings, maybe a bushing ??
ok if john dont know…
i have seen that frame or simular in an artist museum noth of berlin germany.
so if John dont know it, may be its an old artist frame build in the USSR. in the early 20 century they made bears riding bikes and unicycles in cirkus. if you look on saddle and how strong the frame is…
metric screw thread?
If the Russian bear is following you on that machine in the forest: Make sure you have a bigger wheel 
I believe it has sae ameican threads?
Is that icky bike seat a Messenger? They also made unicycle seats (rectangular mostly), and were the company that manufactured the old Schwinn seats (through the mid-1980s). Those big holes in the fork legs are for the bearings; cartridge bearings in those dimensions are very common, for unicycles and all sorts of machines. Those are better bearing holders than most bargain-priced unicycles.
Or could be a custom job for any circus artist around the world. If the bolts are non-metric, more likely US-made, or depending on age, could be from other countries that haven’t been metric for a long time. There are plenty of skilled craftsmen out there who make beautiful props for performers who can afford them.
As for cycling bears, bikes yes, unicycles no. If you know otherwise, I’d love so see any links! In person I’ve seen a chimpanzee ride a unicycle, and a bear ride a bicycle (Moscow Circus in NY). Most impressive of all, though, was an elephant walking on a rolling globe (Latvia State Circus)
Your wheel only has to be bigger than one of the people you’re with… 
Very nice find. Looks very strong below the seat post. I am sure it has an interesting story behind it. This is the sort of rare thing I hope to find at yard sales.