I wrote this up just before the last post above. Still, most of it applies.
There are several other things that contribute to the strength and durability of the wheel. One of them of course is the build job. I and our sons got wheels made by Peter White (see
http://www.peterwhitecycles.com/wheels.asp ) after all the glowing reports on the tandem forum from tandem teams doing loaded touring on his wheels and not having any trouble. If he can build wheels with a lifetime warranty for tandem teams doing loaded touring with nearly 500 pounds gross weight (all luggage on the bike), you don't need to be looking at non-standard things like using a rear wheel for the front of a single bike. Peter White says that if the wheel is built well, even tandems don't need to go to 48 spokes. (48 would still be better than using a rear wheel for the front though.)
For the rear, you would do well to use a rim that has the spoke holes off center to virtually eliminate the dish, as shown here:
Deep-V rims add strength too, so at least for the front, I would go with something like the Velocity Deep V as shown here:
This rim is not so deep that it would give you any extra trouble handling the bike in strong, gusty crosswinds, but it will be able to dissipate more braking heat in long, steep, curvy downhills. If you have two wheels with identical hubs, spokes, number of spokes, and quality of build job, but one has a deep-V rim and the other has a low-profile rim, the one with the deep-V rim will be quite a bit stronger and more reliable. The deep V is not just for aerodynamics. Unfortunately I don't know of any deep-V rims with the off-center spoke holes for the rear.
Instead of going to a non-standard fork, you would do better to go to a bike that uses 26" road (not MTB) wheels. Using the same hubs, the smaller rim results in a better spoke bracing angle which also increases the strength.
Tandem rear dropout spacing is usually 145mm, not 140. (The front is still 110.) Santana and, I believe, one or two other manufacturers, use 160 in the rear for greater strength. Santana offers 16-spoke tandem wheels that have a good track record for reliability, something that would be impossible with the common hubs.
Note also that the reason Shimano uses only cup-and-cone bearings, not cartridge bearings, is that cup-and-cone, when adjusted right, last much longer than cartridge bearings. In a given size, cartridge bearings cannot accommodate the same size and number of ball bearings as cup-and-cone bearings. When there's a durability problem with cup-and-cone bearings, it's because they are adjusted too tight. Unfortunately, even on the showroom floor, most of them will be adjusted much too tight. People adjust them so they feel smooth and have no play in them when they're out of the bike, and then when you squeeze the skewer down, you actually shorten the axle, making the adjustment much too tight. When the wheel is out of the bike, there needs to be a little play in the bearings. If it's the right amount, this will just barely disappear when the skewer is fully squeezed down. From my own experience, I would estimate that cup-and-cone bearings should last at least 100,000 miles if not indefinitely if re-packed every 10,000-20,000.
This message was edited by whittierider on 7-24-08 @ 11:11 AM
