Another one, is that my unicycle isent so high, when i sit on it, and i have placed the seat as high as i can, i am bending my knees pretty much, and after cycling for about 2-3 minutes, i feel some small pain / pressure in my legs, but it goes away after like taking a break for 2 or more minutes.
I think too little air in the tire can be detrimental. I’ve heard some people prefer to learn on a soft tire but I try to pump my tires up to the max sidewall rating for learners/freestyle. A tight tire will respond and turn much better than a soft one.
Unicycling is easy if you are able to get through the frustrating learning stages with patience and the knowledge that it will only be a matter of hours before you get to the level you wanted to be instantly.
If you can get hold of a longer seatpost, (try http://www.unisalg.dk/) then adjust it til you can straighten your leg without stretching too much- reducing the knee bend and the pain hopefully. You could get a new one while you are there instead if you want, and lend your short unicycle to a smaller person. Make sure if you buy a seatpost that it will fit your frame- eg 22.2mm or 25.4mm.
Congratulations on taking up the sport of unicycling. You’ll get it with a little patience and persistence and then you’ll be hooked on unicycling like the rest of us. I’m a really visual learner and I didn’t know any unicyclists in the area when I learned to ride last summer. I relied on youtube videos, which have helped me progress pretty quickly IMHO. I compiled some of the videos that were most helpful into the website that is in my signature line. Good luck and don’t give up.