Wheelset upgrade

The best aero wheels will net you roughly an additional 0.5-0.8 kph at 40 kph, not huge by any means.

The Zipps are good choices, although I would likely go for the 404's all the way around. They're fine for climbing. Even if you just did 303's all around, you'd still be in great shape aerodynamically. Other wheels to consider are Mavic Cosmic Carbones. They're very aero wheels that aren't too bad climbing. They're only real weakness is the rear hub, but that's the case with all Mavic's boutique wheels. Corima Aero wheels are stellar in just about every aspect. Shimano's C50 is another excellent option if you run Shimano or SRAM. Campy's Bora One and Bora II are both excellent options, as is Fulcrum's Racing Speed (which is just a Campy Bora with a different lacing pattern and a different name. It's for Shimano folks who can't bring themselves to buy Campy stuff.) All three can be used with Campy, Shimano, or SRAM. You just have to specify the group you'll be using at purchase.

Of course, you can go off the board and have your own wheels built up. Zipp sells their rims, and Edge Components makes rims, too, although the Edge rims have never been tested in a wind tunnel. I'd give the Zipp rims the edge in a custom built set. In fact, my next set of aero wheels will be customs with Zipp rims.

Frankly, I'd skip Reynolds wheels. While they're structurally strong as hell, aerodynamically they're inferior, especially in cross winds. Zipp rims/wheels will perform the best in cross winds.

I guess I should also mention HED wheels. They're very aero, their deep section rims are, but their hubs are [censored]. They don't sell rims separately.

if you're on a tight budget then it's worth a look at planet x wheels they currently do 3 deep rim carbon aero sets . number 1 is 2 50 mm rims for £399 then it goes up to 1 50 mm and 1 82 mm for £399 then it goes up to 1 82 and 1 108mm rim for £399 this is the cheapest carbon wheel on the market and check www.planet-x-bikes.co.uk to see them in the shop