Hey there, I don't really know of this frame at all but I would think it is meant for 26" wheels. And yeah, it is definately better to get trials specific stuff, from this website: http://www.tartybikes.co.uk Because trials bits are literally many times lighter than say, bmx or mountain bike parts. And yes, you can have 'freewheels' on the cranks [FFW], which means you have to have a fixed rear hub. I think they are most common on mods though (20") so you shouldn't worry about that