Originally Posted by dhk2 .
For slow-speed, steady climbing, (eg 8 mph or less), you can ignore air resistance and assume that all your power is going into either rolling resistance or lifting your body/bike weight up the hill. The power required to match both of these forces is proportional to weight. So for a given vertical rate-of-climb, power-to-weight ratio is going to determine your speed.
Last year, after my trusty Easton rearwheel finally failed (at 30K miles), I picked up a bargain set of "lightly-used" DT Swiss RR1450 wheels from my friendly and trusted LBS, saving about 225 grams of wheel weight, or 1/2 lb, or the equivalent weight of about 1/2 a small water bottle. Since my all-up weight (body, bike, shoes, clothes, seat pack) currently weigh a total of 220 lbs (yes, I'm 25 lbs over the old race-ready weight), that 1/2 lb represents 1/440th of my total, or 0.23%. On a steep 20 min climb, going 0.23% faster saves 1200 sec x .0023, or 2.76 seconds. For me, as a non-racer just doing club rides, that time savings doesn't mean anything.....since the skinny climbers like you beat me on that 20 min climb by 3-5 minutes or more.
The obvious answer for old heavy guys like me is to lose the 25 lbs of fat, not spend money on lighter wheels. OTOH, you're at a good race weight now, and depending on where you're finishing, saving that 2-3 seconds (more on a long event with say an hour or two of low-speed climbing) might make a meaningful difference to you.
As an aside, the RR1450's seem to be high-quality wheels, with premium hubs, rims and spokes. They came with Vittoria Diamante Pro Light's, in 25mm width which makes for a really smooth ride and stable, grippy road feel. I'm hoping to get many thousands of maintenance- free miles out of them.