Before looking forward I will start with a look back. Historically, MUni began with 20" and 24" wheels. Probably for no reason other than that’s how unicycles came. The 20" riders were mostly in Europe, with the guys in the UK in the Polaris Challenge and Thierry Bouche riding down the Alps. Over here, most of us discovered the trails on 24". I never had any interest in riding a 20" on trails; they’re slow and get stuck on all the bumps! My 24" Miyata was nimble, fast and lightweight, but the 1.75" tire had its limitations. I had to keep the pressure high to prevent flats.
When we started building our own MUnis, we went immediately to mountain bike wheels (26"). I still have my old Roger Davies carbon fiber frame, which is a featherlight work of art, but only fits tires up to about 2.2". Then Bruce Bundy and David Poznanter discovered 3" downhill tires: the Gazzalodi. These rode so much better than the skinny stuff that riders on technical stuff immediately gravitated to the fatter tires. They made the really technical stuff easy, and the impossible stuff rideable.
Pause for a couple of years while unicycle technology caught up; now we have many choices of splined axles and cranks. And more choices of tires. And brakes, which opened up more new possibilities of riding the steeps (and trail-coasting!).
So now we’re in a place where brakes are almost a must-have for steep technical riding (they sure were for Unicon!). Also I think 26" rims and tires have been getting to where they work better for unicycling? Or are people just rediscovering what the MTBers have been on all this time? It was thought the 24" wheels were sturdier, and the really wide tires were what people wanted. 26 x 3" tires were pretty huge and heavy, at least a few years ago.
Now you can get a better, stronger 26" wheel with a tire that will handle the terrain. It seems like a logical size for today’s equipment, with all the choices of the mountain bike tire market available. Inn 29" it’s still hard to find the right combination of rim and tire (though KH has done a lot in the rim department). 29" seems to be getting gradually more viable for more difficult trails.
I have a 29" MUni, which I don’t ride much (since I now have a MUni Coker). Part of this is because I’ve been through several rim/tire combinations and still haven’t got something that’s great on the technical stuff. It’s much better than the skinny rim and medium tire I started with, but I still struggle with the tire flopping from side to side and generally feeling like my wheel’s in danger of folding.
Fixed gear hub? Only useful for one-way riding or relatively flat stuff. It would suck if you didn’t have a ride up the hill. But there’s a market for downhill bikes, so this is a possibility for unicycles as well.
CVT hub? We can hope so, for all unicycles. Someday. Cha-ching!
Handlebars? Corbin has been pioneering in this area and it seems to show promise. I see MUni handlebars has having more consideration for dirt and rock-smashing (bash guards).
Brakes? Definitely. Maybe someone can come up with better ways to modulate the braking force. My problem, as an inexperienced uni-brake user, is keeping the brake tension steady while banging down the bumps. It would be nice to be able to click it into a certain position and then maybe let go of the lever to get through some nasty stuff. Maybe a lever with notched settings, or like a car’s parking brake?
And in the future I’d like to see more helicopters!