This is actually a tandem question but since it involves specifically a weight and wheel strength issue I decided to post it here. (There are teams in the tandem forum that weigh less than I do.)
I purchased a used tandem via craigslist. It uses 26" 48 spoke wheels with a thread-on freewheel. When I purchased the bike, the rear axle was bent slightly and so I replaced it and so far so good. I have no idea what the previous owner did to bend the axle but since I'm currently planning a tour on the bike over a rocky trail in the middle of nowhere, I'd like to make sure that the wheel is solid. I'm trying to decide which it a 'better' wheel- the stock 48 spoke wheel with a thread on freewheel that means the bearings (and therefore the load bearing surface of the axle) is pretty far inboard. The other option I've found is a 40 spoked 7 speed wheel that uses a cassette freehub body which puts the bearings farther outboard making the axle less likely to bend but also uses 8 less spokes to support my wife, the bike, and I (somewhere in the neighborhood of 550lbs). Both wheels are 135mm OLD so no problem with funky tandem spacing. Correction: The wheel I was looking at is 145mm spaced, and my tandem is 135mm (i just measured). I've found some White Industries 40 hole hubs that are 135mm spaced but they cost more than I paid for the bike and they aren't even built into a wheel yet. I guess I'll keep looking and see what I can come up with in a more affordable option.
What say you Clydesdale forum?
► Keep the stock wheel which has worked fine for my wife and I so far.
► Get the new wheel that should be easier on the axle but uses 8 less spokes to support a large load over an uneven surface.