I learned to ride last summer and this year I have been able to go some distance on my 24" uni. I am ready to bail at about two or three miles because my butt is sore and my feet fall asleep. I have done a few long rides, up to ten miles, but I have to take a break when I’d like to keep going. How can I fix this trouble? 
Get cycling tights, they really do help. And, what seat are you using? If you plan on riding distances, a good saddle is important. Playing with the angle of the seat helps too.
It’s a basic foam (I think) saddle.
It might help to know what your current saddle and pedals are.
Saddle:
Before I had only known an early 90s era stock schwinn saddle. It hurt, especially initially. I had to just build up endurance with the pain. Then I got a KH freeride, what an upgrade that was. Now I don’t feel any pain and I don’t really even notice that I’m on a unicycle for shorter rides. Saddle soreness only sets in around the 2 hour mark.
Pedals:
Again, before I had only known the stock schwinn pedals. They looked like this:
They would hurt my feet, usually in the arch area. It was a sharp pain that made me feel like I had folded my foot in half lengthwise. I’m pretty sure the pain was in part related to the pedals not having enough surface area for my feet. I also had to waste a lot of energy ensuring my feet stayed on the pedals.
I moved from those to the cheap, generic aluminum pedals with stud inserts for muni. Ever since then my feet stopped hurting. Those had a larger surface area and unlike the other schwinn pedals they were one solid, rigid piece instead of the multi-piece surface with a lot of give. I suspect that this kept my foot from arching on the pedal itself. When using that pedal above the two black plastic surfaces had give and would slope downward, which made the metal bar in the center apply pressure directly to my foot. In some respects it was like riding with just a metal pole sticking out of the crank. The solid aluminum pedals apply pressure more evenly across the entire surface that comes in contact with your shoe.
It might also be useful to look at your shoe. Make sure the sole is rigid enough.
Hi jbtilley,
Interesting comments on the pedals.
If it’s not too much trouble, could you post a picture of the pedal you are using now, so we (I) can see the difference between that one and the picture above.
I’m thinking of getting pedal upgrades myself. I would never ride on wet or even damp cement with the pedals I have now. I’m pretty sure my feet would slip off the pedals.
Another question about pedals with more grip…
Does more grip make it more difficult to dismount in a hurry without falling?
How much control do you have when you have to dismount or upd?
Sometimes, I slip my feet off really quickly on purpose so I can land flat on my feet.
Can you do that with grippy pedals?
Thanks!
57UniRider
I’m using these:
http://www.unicycle.com/unicycle-hardware/pedals/dx-pedals-1.html/
They have raised metal studs in them, so the #1 worry is what happens when you botch a free mount. I’ve never had an issue with my feet coming off those pedals during a dismount or UDP. The only issue I’ve ever had with the studded pedals (when compared to the ones pictured in my previous post) is that it is more difficult to adjust my feet on the pedal. Not impossible, just more difficult. I could slide my feet around the old pedals all day but I almost have to lift my foot off the studded pedals a bit to adjust foot position on the new ones.
Then again I use a shoe with a tread that makes it more difficult, but I like that my foot is better locked in.
Please take this post with a pinch of salt, as I am no expert.
All of my UPDs were fine with pinned pedals. I’m a big fan of wellgo, because they make pedals for other brands, and you can get the same thing for much lesser.
Crap cheapie plastic pedal. I used it for a few days when I was learning. Not much grip, feet can slide around.
This is a nimbus pedal, something like this is more than enough for smooth riding or muni.
This is a wellgo pedal. Notice that it is identical to the Nimbus.
Odyssey Twisted PC Pedals. Lots of people love this. Plastic pins, but I’ll still wear those kneeguards. As a new rider I find it too grippy, gives me trouble when I’m trying to reposition my foot. Not sure if slippery when wet.
Odyssey Trial mix. Not as grippy as the plastic ones above, but metal.
I have these on my mountain bike for over a year now. Probably the kind people who need massive grip want.
I wear these 5.10 shoes. This picture was taken when it was new. Much dirtier now. 
I think any shoe with a flat base would stick well to pedals.
It depends, once I tried to do that (my brain did could not decide which foot to put down first). I stopped for a split second, and ended up having to jump off backwards to avoid falling.
I have the Animal Hamilton PC pedals and a basic foam seat. Would the Nimbus gel saddle work better?
I’ve ridden with them in the pouring rain, and also where my shoes have been getting muddy, and been surprised how well they still grip. I have the gashes to show for where the pins attacked my legs, but I’m sure they’re a lot better than metal pins.
Make sure you have a good seat with good padding. Stand up while riding periodically. Cycling shorts are a good idea but I don’t use them. Also shift the weight of your bottom from left side to right. That is push your crotch as far as you can go to the left where most of the weight will be on the left pelvis, ride that way for a ways, then shift your weight to the right side and back and forth. Break up the monotony of a long ride, jump off 10 to twenty curbs as you ride along. (This will get the blood moving again on your under parts.) If your able and in the city practice hopping at stop signs and signals. When you are hopping the blood will circulate again at the seat area. In other words do what you must not to just sit in one single spot on your seat mile after mile.