It's not a super secret, but use a double eyeletted rim. I'm partial to the DT Swiss RR1.1 hoop. It's a little heavier than the Mavic Open Pro but I find it feels stiffer when standing and climbing. Overall I like the feel of it compared to an Open Pro built around the same hub/spokes.
Additional benefits: Wear indicators on the machined surface to tell you when the braking surface is nearing life's end. Gatorskins aren't a humongous pain in the butt to get on the DT rim. The Mavics tend to run a little on the high-side of manufacturing specs, and tight tires are a real workout to stretch over those hoops.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.