Originally Posted by
chaadster
Well, reduced drag is always reduced drag, regardless of speed. Whether you think the reduction is of benefit is a personal decision. Most sporting riders will see the potential to gain more speed for a given effort level, or to maintain a given speed for a certain reduction in effort, to be a benefit.
FLO Cycling has shown that drag reducing benefits accrue at all speeds given sufficient distance, and that more time is saved by reducing drag the slower one covers that distance:
FLO Cycling - Cycling Wheel Aerodynamics - How Speed, Time, and Power are Affected by Reducing Drag. Of course, that's not how sporting riders measure benefit, though, as most of us want to go faster.
Another example of benefit can be seen in this Cycling Weekly video where "benefit" was demonstrated over just a constant effort of 10 minutes duration at a commonly produced 200 watts:
How much faster are aero wheels? (video) - Cycling Weekly
Sure, theoretically. I'll take your word on it. I read somewhere, but cannot find the link, that aero wheels matter at 15mph and higher, but I'm happy to stipulate that you're correct.
But, in actual practice, when I ride the same route I've ridden literally more than 800 times (i.e. lots of data) with my Enve aero wheels (pre 3.4 version) and with my HED Belgium wheels, and in looking at the data, I see no consequential or even statistically significant differences. So while the Aero Enve wheels may matter over a flat hypothetical 40K (same distance as my loop), a lot of other factors matter more. What is noticeable though is the 200g difference in weight between the wheels on the hills (it's a hilly route). I have a pair of 1700g wheels, and there is a very noticeable difference there and much larger than the difference between the Enve and the HED wheels.
So what I'd add qualitatively, is that the difference from the carbon ENVE 1200g wheels to the 1450g HED wheels is starting to get to the point where, for most riders, it's not going to matter. There is a difference there, it is noticeable but it is much much more noticeable from the Enve wheels to the 1700g wheels. So from an economics perspective, getting a pair of ~1400g alloy wheels for $1000 is a heck of a deal compared to $2700 for a pair of carbon tubular wheels and against $650 for a 1700g pair of wheels. Spending $350 more to get to 1400g is a good deal (dropping 300g of rotating weight).
I like my Enve wheels, but I don't know if I'd replace them today with another set at those prices. I'm pretty happy on the alloy HEDs even after having ridden them in the mountains. They perform very well. When comparing the tubular HEDs to carbon clinchers, it's a no brainer - go with the alloy HEDs, high quality hubs, aero spokes etc...
J.