What components (rim, hub, spokes) would you use to build a very strong 36" wheel? I’m thinking 48 spokes, stainless for looks, is that correct?
If you were to put two of them on a 36" mountain bke, what braking system would you use? Consider that a bke may go much faster than a uni, especially coasting downhill.
Here are a few threads you might want to look at
If you build up a 36er you need to show us some pictures 
I’ve a lot of experience building wheels for Unicycles and tandems. 48 spokes is not necessarily better, for one, it would result in a less-optimal angle between the hub flange and the spoke, which would put more stress on the flange and cause more wind-up during pedaling (or disc braking). 48 spokes would also limit your choice of rims (not to mention hubs).
Spokes? Stainless. There aren’t any real choices for spokes in this length. Rim? Nimbus Stealth Pro.
Hub? Ah; the hub is the interesting problem. Are you building the frame? If you went with a 160mm axle tandem rear hub you’d get wider flange spacing out of it. I’d go with the Chris King Universal Disc tandem rear 160, but for a non-tandem I’d leave the alloy drive shell. For the front, I’d go with the Classic Cross if you’re going non-disc, or the ISO front if you’re not.
Brakes? Interesting dilema. I can’t see any reason that v-brakes wouldn’t perform as well as they would on any other bike, except this bike is going to be a little heaver. If you’re going with a disc brake, you’ll want something with a big diameter rotor, and a brake with some serious squeeze. Any of the good bike DH brakes would do the trick – unlike tandems where you’re trying to stop 350-400#s of bike and riders, you shouldn’t have heat buildup issues with this bike. Note a V-brake in the front would allow a wider-flanged hub which would result in a stronger front wheel. On my tandem I run disc rear and a traditional road caliper brake on the front.
The REAL important part is to get a good, uniform, high-tension wheel build.
A bit off topic but while i was in new zealand (unicon) on the way back I went past a bike store where a guy had built a 36" mountain bike. 
Couldn’t that be solved by lacing the 48 spokes 4x?
I don’t know the strength difference between the modern Coker rim and the Nimbus Stealth. I believe the Stealth is slightly heavier which would imply that it is made with a bit more material and is hence stronger, but that may just be because it needs to be stronger to withstand the larger spacing between spokes. The advantage of the eyelets can be nullified by using appropriate washers under the spoke nipples.
The larger surface area of the rim also means that it would be more resistant to overheating. Using rim brakes would also suggest using the Stealth rim with its machined side walls.
If using disc brakes, on the other hand, the wheel will have more leverage than on 700c or 26" rims, meaning that the brakes will be correspondingly less effective and/or place a higher stress on the hub and spokes and disc brake tabs.
However, since people are riding 36er’s with front discs I don’t think it should be a big worry. That will be a trend in any discussion about strength, there is what is technically the strongest, and then there are all those options which are strong enough.
The Coker wheel is 36 hole like the Nimbus, the QuAx is 48.
The Nimbus has the big advantage (in this use) of the machined braking surface.
Per Coker’s web site, their hubs and rims on the Big One and V2 are spec’d as 48 . . . http://www.cokercycles.com/
Yes. A 36 spoke 3-cross would be about the same angle as a 48 spoke 4-cross. A 36 spoke 4x would be even better.
They both look adequate.
I concur. Any properly-built 36" wheel should do, but an improperly built wheel will certainly be more likely to fail than an improperly built wheel of another size. My intuition says to be more concerned about trying to find as wide a hub as I could, but this is nowhere near as important as the overall spoke tension. I wouldn’t, for example, trade a quality hub for a wider hub of lower quality.
Wide rear hubs and disc brakes can be a challenge for the frame builder to accommodate. The frame stays need to be wide at the hub, narrow at the
bottom bracket, but you end up having trouble finding room between a very wide rotor and the narrow cranks.
Do you think that the extra 5" of chainstay might help 
Great thoughts and tips!
Any thoughts on using a tandem hub, very strong and wide, with gears for a bicycle.
Duh. Yes, it would.
Ken
My apologies, the spec has changed in the last year - I hate incorrect information on the forums…
Thanks
Mike