There are a lot of wheel sizes and types out there to choose from. It really depends on what type of riding you want to do, (do you want to ride long distances off road, or are you trying to learn some tricks?) and how big or small you are.
– This is a HUGE wheel size best used to travel long distances. Running shorter crack arms on a large diameter wheel like this means it will be harder to pedal and balance, but once you get the hang of it, the the payoff is high speeds of over +20mph which makes it possible to cover pretty amazing distances on one wheel.
29″ Muni (Mountain Unicycle)
– When paired with a high-volume mountain bike tire (2.3″-3″ wide) and longer crank arms (150-175mm), this wheel size can roll over just about anything. If you want to try to keep up with your cross-country mountain bike buddies on flowy singletrack, then this is your ride!