There is NO WAY any normal bikeshop will be able to do that much modding to a unicycle. Most of them don’t even know how to do matinence on a unicycle let alone put a disc brake on. It requres a special hub and frame. Plus a brake post and the brake itself.
If you had lots of money you could have a machinist make a hub with rotor mounts and have someone weld on some mounts onto a frame.
I’m not sure (since I’ve not seen the Quax hub) if it would be possible, but I think it might be feasible to modify a Quax hub to take a bolt on rotor, by removing a bearing spacer and bolting/welding on an adapter plate between one flange and the bearing that could take the bolt-on rotor. I don’t know if there would be space without looking at how disc brakes work, how much room they need and how much room a Quax hub leaves. I would also assume that the mount for the frame is readily available to weld on after-market.
So if it could work, a fairly experienced machine shop (provided with good drawings and a detailed description of what needs doing) should be able to make the modifications for a reasonable sum of money. I certainly know of several places here in the UK that would be happy to do this kind of small machining. I would try it, except I don’t have the time or money.
Now that i think about it, It would be possible to make a bearing spacer with rotor mounts that slides onto the splines of a hub. Only certain hubs have full length splines though. Kh 05 and profile would worj.
Disc brakes sound a great idea. I’ve had a hope mini on my mountain bike for a few years and found it provides much more consistent and reliable braking than rim brakes. I think it would be great to see mass produced disc brake compatible components for unicycles in the future.
+1, Dustin. It took alot of work to make mine. For a standard direct-drive hub, there is a product made by First Principles in Canada that bolts to the flange, and provides both the disc rotor mount and the spoke holes: