Im wanna start Mountain Unicycling

I have been Unicycling for 2 months and I can unicycle really well but i want to start MUning my insteam is 17.5 what size wheel should i have? I have a 20" do i need to go bigger, because im quite small I wasnt sure.

the general vote is 24 inch unicycles are best for muni. but you can defiantly use any size you want for it. Might i suggest the $300 Nimbus’ from this page. http://www.unicycle.com/unicycles/rough-terrain

Unicycles: Best used defiantly.

Unless your unicycle is particularly flimsy, just start riding the one you have on easy trails.

From your inseam, you can find the largest size you can ride:

(wheel size)/2 + (crank length) + (seat tube length and crown height) + (seat thickness) + (shoe thickness) = (minimum inseam)

So, for a Torker DX 24:

24/2 + (150/25.4) + 8 + 2 + 1 = 27 inches minimum inseam

Unless you cut the seat tube, which would probably let you get it down to 22 inches. 21in with 127mm cranks.