I still have the original made in Chicago Schwinn 20" unicycle with cottered cranks 
from 1978 that I learned to ride on. When I bought it, the seatpost at full height was too short for me. So I special ordered an optional longer seatpost (about 14" long) that Schwinn offered. I might 
even have the original shorter seatpost somewhere and would love to find it because it would work 
for my 10 year old son to learn on. I’ve looked extensively and haven’t found the seatpost. I could also try measuring out and drilling 3 or 4 more holes and cutting off the bottom of the long seatpost that I do have. Or, if I’m very lucky - someone could have a spare Schwinn seatpost available.
I have one! If you pay shipping you can have it. I am in NC
Yay! That’s awesome 
PM sent.
It’s perfect!
My son tried it this afternoon, at the 2nd from the lowest hole. It was manageable, but still tall. So, I set it down to the lowest hole, and it’s the perfect height for my son ! Thank you very much, sir! He practiced for about a 1/2 hour today :D.
:d