I bought this unicycle for $10 and I thought because it was a Sears product I could find out some stuff about it on the internet. Contrary to my belief, I haven’t found a single piece of information about it. Could somebody please help me? Here are some pics:
Calling John Foss.
I think over time sears has sold a few different cheap uni models. I’m glad I didn’t have to learn on old uni seats.
Probably a Hedstrom. You can look them up. They make (made?) “juvenile” bikes and tricycles. Note you got some of those tricycle parts on your Sears uni, namely the axle, cranks and pedals. That setup is good for one big drop. But just the drop part. On landing, both pedals might shoot off. 
Yours is in really good shape! With those old Messenger seats, you would usually see the base sticking completely out the front end, like a big, square tongue. I have one like it, with the red & white seat. I guess that seat’s in pretty good shape too, as well as the one on my Columbia at the left there. Not that I plan to ever sit on them much…
A lot of old crap isn’t so bad, except the seat
It’s likely a 22 mm seat post. Here we must bother John Foss again and ask if it’s a strange seat post that won’t fit a KH seat.
Old unis are fine for learning, just buy a newer (stronger design), before you start hopping. John seemed to like the condition of the seat, but he is a collector. Your ass will be much happier with a modern KH seat, riding. For 10 $ it’s a good buy, but invest in a good KH saddle if you want to really ride it. Putting a 50 $ saddle on a 10 $ uni might seem odd, but it’s a great buy. Everyone loves KH seats and hates the old time seats like a kick in the ass. Also, it is easy to move nice seats from one uni to the next, so investment in a nice KH seat (free ride or trials, both are good, avoid air seats unless you are eccentric), is never wasted money.
I’m not at home to measure, but I’m pretty sure the Hedstrom post is skinnier than any normal size; skinnier than the old 7/8" Schwinn spec. Don’t waste a good KH seat on that POS. If you want to use it to learn to ride, use the “classic” seat that’s on there. Generations of earlier unicyclists rode and learned on those; so can you.
And then you’ll appreciate a modern replacement cycle all the more!
John is a hard ass
But if he says a KH seat won’t fit, he’s likely right, don’t waste your $ on my idea.
To bad, despite hard ass John’s valid opinion, them old seats were plenty hard, and not everyone could stand them. I bet even John doesn’t like them, he just sorta loves them as a collector. Get some closed cell foam and duct tape. Or better yet, a better unicycle.
Thanks alot for the help guys. I didn’t buy this to learn on, I just bought it because it looked cool. The seatpost on it is thinner than my other unicycles. I’m not sure on the exact measurements.
Sure I like them. Or appreciate them, at least. But to sit on for any length of time? Hells no!
I probably weigh 50 pounds more than I did when I learned to ride, which is also a factor. You can still use a seat like that for learning to ride, but you wouldn’t want to use it for any sustained riding. Or dropping. 