umm… I dont have much expertise in the wheel-building industry, but I would imagine it wouldnt. it would work to some extent, but the only way I could see it working is if it was a 13 hole hub and a 36 hole rim. that way you could skip 1 hole every spoke. a 28 hole hub ona 36 hole rim would work, but it would look like total hell. you need to buy a 36 hole hub
i couldnt do it
i had a shitbox unicycle with a 28 hole hub, and when i bent the rim i was considering the same thing, getting a double walled rim put on it but the guys at my local bikeshop could not come up with a spoking pattern to fit. I just decided to buy a new unicycle, hope this is of some help,
Mark
Re: 28 spoke hub in 36 spoke rim?
Personally I haven’t done this but I don’t think that it’s a very good idea because the rim needs to be tensioned uniformly. In any case, why do you want a double wide rim?
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The hub won’t stand for big drops, so you don’t need a DH tire.
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You will have only 28 spokes, which is underkill for the tires you will put on a double wide rim.
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Tires that go on double wide rims are, in general, not suited for road use, which is what the hub is designed for.
Your wheel will be well matched if you use a 700c 28 hole rim and the fattest road tire you can put on it. Something like the Velocity Deep-V or AeroHead, or Alex TD17.
Which hub are you dealing with? The Sturmey-Archer ASC 3-speed fixed gear hub is rare and very expensive. If that it the case you will want to be very sure of your wheel builder. In addition, a gem like that should be in a very nice unicycle. Otherwise, you are probably not dealing with a fixed gear, which means your wheel would probably be unusable as a unicycle (ask Sara from the West Coast).
the hub is not for a unicycle, that’s why i put this in JC originally. the reason why i want a double wide is because the front tire on my bike is a 2.175" on a double wide rim and it’s way fatter than the 2.2" tire on the rear normal rim with the 3-speed hub (Shimano or something, pretty low quality). i want to keep the 3 speed but don’t want the rim. these are 20" wheels i am talking about here.
here’s a pic:
Now it all makes sense =)
I can’t easily find a 28 hole 20" rim with a fairly large width. The best I can find without doing a major search is about half the width of a DX32.
well i will see what my local bike shop says, in the past they have not been the most helpful in their advice. it was hard enough to find someone to build that front wheel with the drum brake, the first place told me it couldn’t be done!
I can get this thread on the topic of unicycling. 
I had the wheel on my Schwinn giraffe rebuilt several years ago. The Schwinn has a 28 spoke hub. At the time I was unable to find a good quality 28 spoke 20" rim so I ended up replacing the Schwinn hub with a 36 spoke Semcycle hub. It’s much easier to find a good 36 spoke rim than trying to find even a halfway decent 28 spoke rim.
My big motivation for rebuilding the wheel was getting a true 20" wheel. The old Schwinn’s used a stupid special rim size (what they called an S7) that was not a true 20" rim so it would not fit normal 20" tires. My giraffe now has a real 20" wheel.
If anyone knows of some good 28 spoke 20" rims I’m sure it would be good info for the people who still have 28 spoke Schwinn giraffe hubs and want to update to a real 20" wheel.
I wonder if SnowCat can make a 20" rim with 28 spokes? If you want a wide rim that’s one option. I believe he is able to do custom spoke drillings so making a rim with 28 spokes would be doable. I don’t know if he does a 20" wheel though.
thanks for the link john, i don’t want to invest too much into this project so getting a custom rim may not be an option at the moment, i will chat with the bike shop guys by me and see if they can find a solution.