Advice on aero wheels

Question

I have decided to buy new wheels for this season. I'm currently riding the Bontrager Race Lite wheels that came with my bike, and now it's time to move to aero wheels to keep up. I'll do about 1300 km of racing this season (approx. 800 miles) where the longest is 540 km (approx. 335 miles), thus I will need good wheels.

I've looked at different wheel sets and considered price, quality and function. I think it has come down to these, but feel free to add anything you miss.

• Zipp Firecrest 404/808
• FFWD F4R/F6R
• Mavic Cosmic Carbon
• Mad Fiber

Although some of the wheels above is slightly too expensive, I think they are worth mentioning for the comparison.

So here are my questions:

• For a good all round wheel, would you go for taller (>58mm), or lower (<40mm) rims?
• Is the price difference from FFWD to Zipp or even Mad Fibre worth it in a TTT race over a long distance with an average pace of circa 35 km/h / 22 mph?
• When spending this much on a set of wheels: Clincher, which I'm currently riding, or tubular?

Any advice would be appreciated, and personal experience would be highly regarded.

UPDATE: In the end, i bought Unaas CS-50.

Answer 1

Except for the steepest of hill climbs, aero wheels will almost always improve speed; however, the choice among race wheels will depend on the types of races you do, your strengths as a racer, how important small improvements in aerodynamic drag are to your goals, and the size of your bank account. For short individual time trials, .0025 m^2 savings in CdA (roughly, one-sixth the size of the difference between a very aerodynamic front trispoke wheel and a "standard" box rim) is worth 10 seconds in 40km and can mean the difference between standing on a podium or grinding your teeth on the long drive home. For citizen-level crit races where crashes are common, you may not want to risk expensive wheels unless your riding style is so dominant that you spend the entire race off the front and turn the crit into an ITT. For a long TTT like the Styrkeproven, aero wheels certainly won't hurt but the benefit of a deep set of rims may not be worth the cost if your team time is determined by the 10th rider to cross the line (in fact, in that case, a cheaper and potentially more effective strategy is to have everyone of the team use tight clothing and low rolling resistance tubes and tires).

Purely from an aerodynamic drag point of view, several of the larger wheel manufacturers (such as Zipp or Hed) provide information on aerodynamic drag differences (in grams of drag "force") between their various models and standard box rims. Most of these differences in grams "force" are measured at either 30 mph or 50 km/h. You'll want to convert this to the average speed you expect to maintain in your various types of races (the aero drag varies with the square of air speed) to make a rough estimate of the benefit you'll reap from switching to better rims. Exact calculations will depend on yaw angle but a handy rule of thumb is that a savings of 50 g of drag "force" at 40 km/h is roughly equivalent to a savings of 0.5 seconds/km at the same power output. Thus, the difference between a box rim and a trispoke front wheel could be around 1.5 sec/km, or about 1 minute in a 40km ITT.