Originally Posted by
Carbonfiberboy
A standard road tandem rim is the Velocity Deep V. That's a very strong rim that we've toured on. On this rim, we run 25c tires at 120 lbs. for sport (350 lbs. total) and 28c tires at 115 lbs. for touring (400 lbs. total). At your lower weight, you could run lower pressures. It's the depth of the rim that makes it so strong. The Velocity Dyad is another popular tandem rim for people who favor wider tires, but I've seen broken spokes on Dyads, never on a Deep V. The Chukker looks like a better choice for wider tires.
Another vote for the 2.0/1.8/2.0 spokes. The thinner center section allows the spoke to be stretched much further, which is what makes double butted spokes so resistant to fatigue. Each spoke still has a working strength of over 250 lbs.
Quality deep V rims are stronger and lighter than their equivalent boxed double-wall eyeleted rims (i.e. Mavic 719). I always specify hex brass nipples along with Deep-V or Chukker when working with ultra-heavy load. These rims can easily handle a 50% increase in spoke tension...nominal 220 lbs to 330 lbs. Higher spoke tension translates to greater radial, lateral, and torsional load carrying capacity. Peak overload is quickly dissipated over several spokes.
The highest possible tension for boxed/flat rims is always lower than that for deep V rims. One major problem with high spoke tension is excessive twisting of the butted spokes. Novice wheelbuilders should draw a straight line on the spoke prior to assembly and use this line as reference to compensate for spoke twist at high tension. Invest in a 5.5 mm wrench to apply torque to the hex brass nipples.
Course even an aluminum automobile rim can fracture if it hits a big pothole. There are no bullet-proof bicycle rim. But deep V is the best available option today to cope with heavy touring. Seek out a good wheelsmith to extract the most performance out of the deep V rim.