Hey guys, I’m a bit confused. I would like you to explain to me in detail if possible, what is the difference between a trials unicycle and a freestyle unicycle? 
I’ve had the belief that trials uni’s were made especially for hopping, pedal grabbing, and grinds. This means a big difference in the amount of weight you want. (less=happy trials) Also, I’ve noticed that most trials have smaller wheels, (20 inch, mostly) which are more manouverable and lighter, but don’t let you go very fast at all.
Freestyle uni’s are usually used (I believe) for shows, demonstrations, indoor stuff. One footed, seat on chest, unispins. things like that. Not much hopping, so weight isn’t such a huge deal. No big treads, tires that are “flat” (have a lot of rubber touching the floor) are necessary for good grip on indoor surfaces. 24 inch tires, since some tricks look better faster, and some are easier to do on a bigger wheel.
I never really see a huge difference in uni’s, whatever they do. The only things that really change are the size of tire and the tread. Buying a freestyle (indoor) vs. a trials (cool tricks) vs. a muni (downhill and offroad) vs. a road uni (big tire=zoom zoom zoom) is all a matter of what you really want to do. These are loose catagories, however. I’m sure you can do trials or road on a muni, and I’m sure you can do indoors and muni on a trials. A uni can do whatever you want it to do, it just might not be the best uni to do it with.
If your not sure, buy a uni for each type! 
Then another one for me!
Short answer: tire width.
Long answer, deftly handled by Vortex OOW.
If you wanted to know the difference between the activities of Freestyle and Trials, that would be a different question. Check out the IUF Rulebook at:
http://www.unicycling.org/iuf/rulebook/
A Trials unicycle will also benefit from metal pedals with teeth (especially for grabs) and the strongest possible crankset. A freestyle uni is better without the seat handle, because that can get in the way for some tricks.
Crank length is a personal choice, but generally a lot longer on a Trials uni. Both types of uni are usually 20", though you can also do both on larger sized wheels.
you can still do freestyle on a trials unicycle.
although it’s not perfect for it, especialy the bmx style pedals which hurt when they hit you, and the tyre makes wheelwalking a bit harder (for me anyway)
but if you do trials on a freestyle unicycle it will be harder to jumpor land drops. (less air volume in tyre)
and it will break after a very short time, proper trials unicycles have a splined hub/cranks which will alow you to do do drops and gaps which will turn normal cranks into spageti.
thanks for all your answers, but I think that what I really would like to know is what tricks are mached up with which unicycle. Which unicycle does what? For instance, although I know you can use either one…which is better for walking the wheel, or one foot pedalling, or hopping, or pirruetting, etc. I can figure out most of those listed for myself just by looking at their differences, but I would like to know the differences between the unicycles in terms of stunts and tricks they perform. Thanks.
The unicycle doesn’t do anything – the rider does. Not trying to be a jerk, but I get annoyed when skills or deficiencies are solely blamed on (attributed to) the equipment, with no regard for the user.
I would suggest watching a uni video, if you can get a hold of one, to see what people do with each unicycle.
Otherwise, I think you’re probably being a bit mislead or are putting too much emphasis on the unicycle itself. You can do pretty well any trick with any uni. Things which you probably already know (if you can figure out which uni would be best for the tricks you listed above):
-
- lighter unis are better for hopping (especially when height is a requirement): trials or freestyle
- stronger unis are better for drops and grinds and grabs: MUni and trials
- smaller unis are better for tricks and stuff needing manouverability: freestyle
- bigger (wider) tires are better for drops and hops: trials and MUni
- knobby tires are better for offroad: you can put 'em on whatever frame you want, but will typically be found on MUnis and trials
- square-crowned frames are better for one-footed tricks: freestyle and some MUni and some trials (I assume there are some)
- unis with stronger cranks and hubs are better for drops, hops and offroad: trials and MUni
I am confident of your ability to choose wisely.
Later,
Eli.
Generally, the freestyle uni is going to be better for any flatland tricks. As you start getting vertical, strength and tire volume becomes more of a factor.
Though some tricks might be a little easier on a Trials unicycle, you have to think of the larger picture of what your final goal is. If you intend to perform tricks, you’ll want a freestyle uni. But if you’re going to perform a combination of flatland and Trials, a Trials uni might be better, though one of each would be best.
Walking the wheel is surely easier to learn on a Trials uni. But once you can do it, it doesn’t really matter how wide your tire is. Outside of that, almost all tricks will be eaiser on the freestyle uni.