I’m a bit confused… Well it seems that I can swap a 32h carbon rim with a 36h carbon rim… but I’m unsure about solving my issue… can anyone tell me if a 125mm alu/ergal/titanium NODISC hub exist? I can match my 32h rim with my m4o 100mm ergal NODISC hub. I can swap the rim and match a 36h rim with an exceed 100mm NODISC hub… Is there a way to build a wheel with a NODISC 125mm LIGHT hub?
Funny you should ask this. I was thinking the same thing. But in short - while no expert I think the answer is “no”.
The only nodisc hubs at 125 are cotterless - as they were around I guess before disc brakes.
But I suspect going cotterless would be a bit counter intuitive if you’re aiming to build a modern carbon rimmed wheel.
I do think that a symmetrical 36” wheel built on a 100mm hub is likely about the same strength wise as a 125 dished wheel. It’s why I think the KH 36er were built this way, on 100mm hubs with outboard discs in their cranks.
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There were diskless 125mm ISIS hubs around (the original Nightfox had one), but they were steel.
I’ve never seen one in anything fancier.
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Ah cool to know.
Think this shows it. I wonder if their hubs were ever sold as parts
I have a feeling that the Nimbus Oregon fat uni was using a 125mm alu hub for a short while (or it was a part). But cannot find it on the archive.org to confirm if it was a disk hub or not.
The main problem, even if such hub existed, would be to find one second hand (or to get lucky and have a unicycle shop have one in their unpublished inventory…
Thank you. I was making a mistake swapping my rim. I’d better use my ergal 32h hub and see what happen
Assuming you are going outboard right side disk with KH spirit cranks. That configuration on a 125mm hub results in a wickedly wide Q-factor like riding a horse
This may depend on the rider’s size. If they are tall/large, this may be a not-that-strange setup. However, if they are a “normal” rider, then… Yeah, large Q-factor, horse riding 
Have you ever ride a Hunirex? I did. It has a large Q-factor. Is it comfortable? Yes it is. What is the big difference while riding? You need to get used to it like when you swap longer/shorter cranks or bigger/smaller wheel
When I first saw your question I wondered if it would be possible to make something from a 125mm aluminum disc hub and a 100mm non-disc aluminium hub in the same sort of a way that the KH Moment hubs were.
It would depend on whether it was possible to press the steel ISIS spindle out of the hub body of each of these. If you could do that then you could cut the 100mm hub body in. two and press it back on to the 125mm spindle with a 25mm spacer between the two halves…
I suspect the alumuminium hub body is shrunk onto the spindle so it may be more or less impossible to get off though.
An alternative would be to just cut a 100mm hub in two, machine back some of the aluminium in from the cut ends and weld or braze in a steel 25mm spacer (pinned into the centre of the spindle for strength and alignment).
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An aluminum spacer could be welded to the aluminum, but neither steel or aluminum can be welded or brazed together. So pinning or screws would be one option. If you can, make your own. I’ve been making mine out of stainless forever because no one made disc hubs when I started out.
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I meant that a steel spacer could be welded/brazed into the middle of the (cut) steel ISIS spindle to extend it with a pin going longitudinally up inside the spindle to keep it concentric and give it some strength. The ‘gap’ in the aluminium probably wouldn’t be an issue as the ends/flanges probably wouldn’t move – if they did putting a roll-pin through would probably be the easiest option.
You are right though, just welding in an aluminium spacer would work – if it was me, my aluminium welding skills would need some revamp (and a better TIG welder 
)
When you made your hubs were they cotterless? I have considered making a hub in the past but machining an ISIS spline seemed like a bit of a challenge. It just occurred to me though that machining a Q-axle type spline would be pretty straightforward though (I’ve made driveshafts like that in the past).
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OK that explains it. I have started with the old square taper (broke to offen on drops). Then to 3/4" square like Primo bmx cranks (muck better) then ISIS spline when it first came out on mntn b*kes. (easy with ball end mill and dividing head) Then manufacturers copied (maybe) my in frame disc and I can buy the dream (but already have several of my own) but haven’t done the Q-axe yet, but it has that potential because of crank availability. I applaud your creativity tho, you are a unicyclist!
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Thank you. Necessity is the mother of invention as they say – and growing up I had more access to tools than I had money to get stuff, so I made what I wanted. It might have stood me in good stead – I’m not sure though