can you cahange a learner into a trials just by getting a new fork (if not please excuse my n00bishnes)
um, no. you could, if there’s enough clearance, swap the wheelset. but then you’d be stuck with a crappy frame on a good wheelset. best to just buy a whole new uni.
Nah, the wheels on learner unis suck so you would have to get a new one with trials rim and better hub (splined if you want a good trials uni). Then you need a trials tire. Then most likely it won’t fit your frame so you will need a new one of those and that usually leads to a new seat post. Your learner seat probably isn’t comfortable so you would then switch that out. Then you will probably want some strong grippy pedals like Jimmy C’s or snafus. Before you know it you don’t have one part left over from the origional uni.
Buy a whole new uni.
The “fork” is generally called a frame in the unicycling world. Frames are not a common point of failure for trials riding (or any other style of riding for that matter). The most common points of failure are probably rims and cranks. Splined hubs have a strong hub/crank interface, and the cranks for splined hubs are manufactured with greater strength in mind. Trials unis generally have tires that differ from your common learner; wider trials tires with a larger volume of air help by softening drops and by storing energy for hopping. If there were only one component essential for your uni to be classified as a trials uni, I’d say it would have to be a 2.5" trials tire on a 19" trials rim. A frame is probably one of the least important components of a trials uni. Changing it will not make your uni a trials uni.
With that said, you can certainly get started learning the basic trials skills with a learner uni.