As someone contemplating the purchase of a folding bike, I've been wondering about this. Why is it that virtually all the 20" wheels I see on folders have 30+ spokes? There are rims drilled for 24 holes (Velocity Aeroheat 406), and I understand it's possible to build good wheels with 24 spokes and 36-hole hubs (http://sheldonbrown.com/rinard/36-24.htm). These should be roughly equivalent to 36-spoke 700c wheels, no? I tour on those and consider them overbuilt, or if you prefer, having a wide safety margin. Tempted to do this with a folder but nervous when no one else does... like I may be missing something.