[QUOTE=mike12;16190788]I said that the wheels might save me 10% in a race, and my average in races is typically 160-200w, so rounding down a touch that would be 15-20 watts. There are races were I spend 10 minutes at 225w and then get shelled. If against the same riders I average 200w and I can finish, that's a 10% decrease in power. Obviously there are other factors but to me that's the gross difference.

For steady state analysis there's a site where you can plug in some numbers:
http://www.analyticcycling.com

However, and I haven't tested this nor can I prove it in terms of math or a fancy websit, but the difference in a mass start race is more than just what power you put out; it's about drafting. Let's take a theoretical example (so it's easier to relate to).

Situation: You can sustain 250w for 10 minutes, give or take. A person on a moped going 30 mph passes you while you're going 15 mph. Your goal is to have a high average speed for the next three miles. You and the moped driver are on that three mile stretch. You have two options.

The first is to accelerate up to 35-38 mph, catch the moped, and draft the moped at 30 mph until the end of the three miles. Once you're in the moped's draft your work rate drops significantly for your given speed, maybe from 450w for 30 mph to something more like 250w, maybe 220w (based on my own experience). This translates to a 200-250w savings in energy. You'll average 30 mph for the 3 miles because that's what the moped did.

Your second option is to simply time trial as efficiently as possible while holding the same wattage, ignoring the moped that just blew by you. Realistically, for me, that would mean going 23-24 mph and holding in the 250w range. Your average will be in that range, slightly less because of the time it takes to accelerate to whatever cruising speed you hold. Using aero wheels might get you 0.1 mph here and there. Say it saves 10% - that would bring power consumption down by 25 watts.

In both situations you're putting down about the same average power. In one you make an initial dig to get into a draft. In the second you ignore the draft.

So, yes, aerodynamics makes a difference, in that in a steady state effort they can make a small but consistent difference. As people have pointed out here if you have a more aero wheelset (or frame or helmet or whatever) it's always going to be more aero (given things like proper wind etc). Technically it'll be more aero at 3 mph but you may not notice the difference - I certainly can't tell at 3 mph. At 30 mph, yes, or 35 mph, yes, or 40 mph, yes.

But much more significant than "aero" is how you ride in a race (hence my reference to mass start races). If I can do one hard effort, get in the draft, and then really really really ease off, I can save much more energy than I could ever save by getting more aero equipment for myself.

This has nothing to do with average speed over an hour, but it illustrates how one can go much faster for that hour.

For example in one race I averaged 27.5 mph @175 watts, at least until I had to slow due to a crash on the last lap of the race. Without drafting, being on Earth, on a flat road, with normal level winds, there would be no way any equipment change would allow me to go 27.5 mph @ 175 watts (and I did have an aero wheelset and an aero-ish frame).

The point is that in racing the most important thing is drafting. The individual's aerodynamics (bike, body) comes in a distant second.

Therefore aero wheels can help in a race. I find that light wheels also make a huge difference, allowing me to get into the draft quicker, therefore letting me save energy sooner. Light aero wheels are the best, and in the wheels in my picture the race wheels are the lightest as well as the most aero, the non-aero training wheels a bit heavier, and the aero training wheels much heavier.

An example in terms of outright speed. My current max speed in a sprint is about 40 mph on a given level road without much wind. I've hit as high as 44-46 mph regularly in the past, and on one set of wheels I hit 48 mph a couple times. My anomaly effort was during Hurricane George, where on a flat road I hit and held 60 mph for about a minute, so about a mile. At that point I had at least a 50 mph tailwind and it was gusting up to 80-90 mph. (Getting to that area we were struggling at 8-12 mph going into that wind, it was brutal.) Anyway those are my absolute best speeds.

In this clip I'm going 49.x mph twice. One is on a slight downhill followed by a slight rise, the other is on a slight rise. Would aero wheels have made a difference? Maybe, but not so that I could hit 49.x mph. It's much more important that I catch the truck's draft. Once I'm there I'm okay for a bit. Keep in mind that in the yellow truck example I'd ridden a very hard 3 hours already and I was a couple miles from home base. In the second I chased the two white trucks up and over about a half mile climb, then rode hard down the following descent to catch them as they were leaving the light. I was already a bit gassed when I caught them yet I still managed to break 49 mph.