Can anyone here state with a reasonable degree of confidence that their aero framed bike translates into increased real-world speed? And how much?
I’m not talking about wind tunnel lab testing- I mean, are you actually faster on your Cervelo than you are on a round tubed bike?
I’m definitely faster on my Felt than my LeMond.
The frame may not be “real world” more aero, but mentally it sure is.
Yeah, but your Felt is a tri bike, and the LeMond is a road bike, right? I would think that you’re actually faster on the Felt just because of a more aero rider position.
More detailed question: Is a bike like the Soloist faster than a Super Prodigy? Is a Dual faster than a Serrotta tri bike? All other things being equal, does an aero frame translate to real world speed? And how much, compared to an upgrade such as aero wheels?
If you do a search for one of my posts from last May, you’ll see the results of a 30’ TT done on a Trek 1000 converted for tri with a Cervelo P2k. For the test, I had the same wheels, and the same bike fit. Can’t remember the exact numbers but it was noticeable. Once I got into the correct fit on the cervelo, there was another significant speed increase.
GREAT!!! question.
Unfortunately, my answer is… no, I can’t tell you how much faster I am on my P3 than a round tube bike of similar geometry.
I can offer a guess and say that when I get up to 22+ mph I bet it is worth a half mph probably. That is only a guess. If you asked me if I felt it is faster than round tubes, I would say definately “yes”, but I can’t quantify that.
I’m faster on my round tubed Klein than I was on my Cervelo P2. But, the 2 bikes fit differently. So my answer is i don’t have a clue of aero tubes make any different, but I would suspect that they don’t make that much difference by the time you slap a couple of water bottles on the frame.
You will ride faster on an aero tubed bike for sure.
Remember “It’s not how fast you are, it’s how fast you look.”
For a more detailed version search the archives for my “Manifesto.”
-I luv u, I luv u, and I luv u!
You got me curious, so I looked up my old post. Here is a clip of it, for details you’ll have to look it up yourself
"I was 0.9 mph faster on the stock P2k in basically the same position on both bikes. "
The post implies that I used the Ritchey wheels that came with the P2k. They would be slighty more aero than the wheels on the Trek, but nothing major.
Tom , thanks, I’d actually looked up the post- it’s exactly the kind of info I’m asking about.
Two things I always forget: The increasing benefits of aero at increased speeds, and the really important thing- *looking *fast. I probably forget them so easily because neither applies to me right now. 
Unless you are Lance or Tyler at the Tour, I think aero frames are pure marketing genius. I went from a regular tri frame (not particularly aero tubes) to a Cervelo P2 last year. It didn’t make me faster.
Cervelo publishes data on their website that is an extrapolation of data they obtained by testing at 30 mph in a tunnel. How long can the normal human maintain 30 mph? Like never. So they say you can save like 3:00 minutes compared to a round tubed frame, but in the real world at 18-22 mph it just doesn’t translate. Or at least it did not for me. I went back to my Scott. Now I have a Yaqui because it fits perfectly.
If any of you have ridden in a peloton rolling along at 30-35 mph, you know that you can’t stay on the front long at that speed. I don’t think you really start to turn the corner, or climb the parabolic curve until you go past 25 mph and that capability is beyond 99.9 percent of the triathlon population.
Aero tubes and wheel cutouts are pure marketing genius, but I suspect very few people could document with a power meter that their output went down at the same speed or their speed went up at the same power on their new “aero” bike.
Chad
Aero tubes and wheel cutouts are pure marketing genius, but I suspect very few people could document with a power meter that their output went down at the same speed or their speed went up at the same power on their new “aero” bike.
From a posting I made about three weeks ago, regarding a 7mile TT I did in 2003 and again in 2004:
2003 bike: Serotta Legend Ti, bullhorns, clipons
2004 bike: Cervelo P2K, Oval concepts A700 integrated bars
Essentially the same wheels (Spinergy Rev-X front, Power Tap with cover rear)
Stats
Year Time Spd Hr Watts W/kg Cadence Weight(kg)
2003 18:19 22.9 165 288 3.60 94 80
2004 17:09 24.5 165 296 3.79 99 77.5
Power went up about 3%, speed went up ~5%. As you know, speed doesn’t increase linearly with power: my speed should have gone up ~1%, all things being equal. But it went up a lot more than that, and more relative to others from the year before (trying to eliminate weather conditions).
I leave it to you to determine where the extra speed came from.
Ken, be patient with me, I’m a technical boob.
Didn’t your power actually go up by about 5%? (3.6 W/Kg vs 3.79)
Why doesn’t speed increase linearly with power, all else being equal?
My power-to-weight ratio went up (the 3.6Watts/kilogram), because I weighed less this year than last year. My average power went from 288W to 296W, or 8 Watts, or about 3%.
Speed doesn’t increase linearly with power, because wind resistance increases by something like the square (cube?) of the speed. The faster you go, the greater percentage of your power goes to just moving air. Generally, you get something like the square root of power increase as a speed increase. So, increase your power by 9%, get 3% more speed. As an example: 250W might get you 11.23m/sec; add 10% power (275) gives you 11.63m/sec (about 3-4%); double it to 500W and you only get to 14.4m/sec (about 30% more). Play with the numbers at www.analyticcycling.com to see.
Wind blows, eh?
This is very interesting. It really shows me that my earlier post was quite silly. After all, even a power meter is not omnipotent, because it is really impossible to identify what might have caused the increase in speed.
Was the day cooler? Less wind? Leg muscles were better rested? I’m not really looking for an answer because any of those things could have been a factor. Maybe your body’s position on the bike is more aerodynamic … who knows? It may have even been the bike, but since a similar experiment with Vision Tech bars, a Cervelo P2 frame and a lower position did not yield similar results, then I gave up on the Cervelo, which was a hassle to maintain.
Thanks for the number crunching on the effects of wind. That was what I was trying to explain when I said that you have to be going pretty fast for an aero tube to make any difference.
Chad
Ken, thanks for the explanation- this is just what I’m looking for.
The conclusion I’m drawing here is that at speeds of over 20 mph or so, aero frames do seem to make a difference, on the order of .5 to 1.5 miles per hour. That’s good to know.
Thanks for the website, too, I’ll have to play around with that.
You said
"That was what I was trying to explain when I said that you have to be going pretty fast for an aero tube to make any difference
Well, no. Given two riders, both of whom have the same frontal area of .55 square meters, one of whom puts out 250W, and the other 500W. Decrease their frontal area by 10% (perhaps by using aero tubes and other stuff), and both their speeds increase by 3.1%.
Don’t draw that conclusion; I didn’t. As Chad pointed out, there are too many variables involved (although whether my legs were rested is irrelevant). I would guess that the aerobars contributed, a better body position contributed, and the frame contributed.
Well-done wind tunnel tests are the gold standard; I don’t know if Cervelo’s data is based on such tests.
The only way that I could see to test aero frames in action would be on an indoor velodrome (perhaps like the one being built in CA). That way you could ride a a specific average power and then determine if the aero frame was actually working, and by how much. That way you would remove the effects of wind and outdoor variations from the equation.
KR
There was thorough discussion of this topic by Andy Coggins some time ago. It was probably in the old forum though, so you might not be able to call it up.
Bottom line was that a faster frame helped quite a bit. Andy was quite thorough in his research as usual. I am sure you can track him down on one of these forums, but he never seems to hang here anymore. Too bad. I miss him.
Here’s mine & wifes experience. We have a 16.5 km loop that is our testing ground. We’ve compared aero frame tri bikes with our round frame road bikes on over a hundred occassions. Bottom line - no significant over all difference.
Now here’s the qualifier - this course has lots of hills but with a couple of decent flat strait stretches. Our conclusion is that the tri bike gains on the flats but the road bikes are definately faster up the hills. In the end it balances out, at least on this course.