I built a set of wheels recently which I didn't weigh, not having a suitable scale, but the parts sum = 1450g. They're Kinlin XC279 23mm X 28mm rims, 460g, 20H and 24H, CX-Ray spokes. Parts cost was $340. I run 23mm Conti 4KIIs on them. I did a non-technical 3000' pass descent with a group this past Sunday. I had to wait a good minute at the bottom for the next rider, another minute or so for the 3rd guy, then more waiting. I'm a short-legged 145 lb. guy on a 52 with a slammed stem, so my bars are only 5cm below my saddle. I was doing 35-40 mph most of the way. They were even further back on the preceding pass descent.
The right lightish wheel and tire combo descends just fine.
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