Coker wheel strength and hub spacing

This isn’t exactly a unicycle idea, but it deals with the coker rim/tire and so I figure this is the best place to ask it. I was thinking of building a coker wheeled tandem mountain bike. The idea would be you could roll over almost everything, granted there are allot of considerations that need to be taken into consideration as far as spacing, but my main question here is do you think the airfoil rim could be laced to a tandem mountain bike hub and still be strong enough? It seems most people think a wide hub is required for a unicycle to give it extra strength, but this would be on a tandem mountain bike. This is mostly for the rear hub, a front hub could always be custom made to fit whatever I wind up doing, but the rear hub with the cassette body is allot harder to manufacture. Most of the coker riders seem to use them for distance, but I enjoy taking mine up and down steps the most, and I’ve done up to 2 foot drops so far too without any problems. So what do you think? I would definitely use stainless spokes if I wind up building this, no question as far as that goes.

Bicycle wheels are generally placed under less stress than unicycle wheels; they carry less weight and they receive fewer side forces. So, you might be able to get away with it. But 36" rim laced to a typical tandem rear hub will not be a very strong wheel; the effective hub width is even smaller than on the stock Coker because of the wheel offset. If you built it with the Airfoil rim it probably would be acceptable for off-road cruising use, but I wouldn’t do drops on it.

coker makes coker bikes with the large wheels. you could probably modify one to be a mountain bike.
-corbin

You might be best off using a geared rear hub or a singlespeed specific hub. That’d make it more centred and hence stronger.

Alternatively a super-posh + wide Phil Wood or Chris King tandem hub. You can get them in wider versions specially for tandem rear wheels, presumably you’re having the frame custom built anyway, so an extra wide rear end (160mm spacing) and super expensive cost wouldn’t be a problem?

Joe

I know they make bikes, but I have a feeling their bikes were not intended for the kind of abuse I plan to put this bike through if it ever gets built. The reason for a tandem and not a bike is I figure that they would be unwieldy on a bike, while a tandem is already unwieldy so it could benefit from enormous wheels. The thing is, I was planning on building the frame myself, with the help of some friends who have more experience welding and the use of the school machine shop. Getting a custom hub might be the best option. The dish I can take care of by building the rear triangle with an offset to one side so the axle won’t be centered with the rest of the bike, but the rim would be centered compared to the rest of the bike. Surly does that with their Pugsly, as does Vicious Cycles with their Thunderwig. I was hoping I could use a relatively stock tandem hub, but oh well. Thanks for all the input, when I get some renderings done in Solidworks I’ll post them.