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Aero Frame Real World Testing

Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Aero Frame Real World Testing

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Old 07-10-18, 01:02 PM
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TiHabanero
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Aero Frame Real World Testing

Has anyone knowledge of real world testing of aero frames?
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Old 07-10-18, 01:04 PM
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Originally Posted by TiHabanero View Post
Has anyone knowledge of real world testing of aero frames?
I don't know of any other kind.
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Old 07-10-18, 01:19 PM
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Aeroweenie.com - Aero Data Compendium

Brew a pot of coffee and have at it.


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Old 07-10-18, 01:35 PM
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TimothyH, I know all sorts of data exists for wind tunnel testing, however as learned from racing auto sports, the wind tunnel does not always accurately translate to the road environment. I am interested in timed tests on the road where there are hills, valleys, cross winds, etc. Very curious as to the efficiency level of these frames when put to the test.
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Old 07-10-18, 01:41 PM
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@TimothyH Thanks for the link.
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Old 07-10-18, 01:43 PM
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Originally Posted by TiHabanero View Post
TimothyH, I know all sorts of data exists for wind tunnel testing, however as learned from racing auto sports, the wind tunnel does not always accurately translate to the road environment. I am interested in timed tests on the road where there are hills, valleys, cross winds, etc. Very curious as to the efficiency level of these frames when put to the test.
That's because one company publishes grams of drag at 12.5 degrees yaw and another posts the # of watts to go 40 kph at 13 degrees. It's obtuse and hard to compare. And then nobody ever rides their bike in one direction on the flat into unchanging wind.
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Old 07-10-18, 01:44 PM
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Originally Posted by TiHabanero View Post
I am interested in timed tests on the road where there are hills, valleys, cross winds, etc.
How would road grade factor in?
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Old 07-10-18, 01:47 PM
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Originally Posted by Seattle Forrest View Post
That's because one company publishes grams of drag at 12.5 degrees yaw and another posts the # of watts to go 40 kph at 13 degrees. It's obtuse and hard to compare.
The fact that many people don't know how to properly interpret the data doesn't mean the data itself is flawed or not useful.
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Old 07-10-18, 02:11 PM
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If @RChung hasn't, he would probably know who has.
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Old 07-10-18, 02:14 PM
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Originally Posted by TiHabanero View Post
TimothyH, I know all sorts of data exists for wind tunnel testing, however as learned from racing auto sports, the wind tunnel does not always accurately translate to the road environment. I am interested in timed tests on the road where there are hills, valleys, cross winds, etc. Very curious as to the efficiency level of these frames when put to the test.
Not to start an argument....but don't you think lab testing would be more helpful than real world? How could you possibly isolate just aerodynamics in a meaningful way for testing on a moving bike outside a wind tunnel? I have a feeling the margin for error introduced by any number of factors would be greater even than the aero differences you're trying to test. You would never know how 'real' any result is.
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Old 07-10-18, 02:15 PM
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Originally Posted by Abe_Froman View Post
How could you possibly isolate just aerodynamics in a meaningful way for testing on a moving bike outside a wind tunnel?
http://anonymous.coward.free.fr/watt...direct-cda.pdf
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Old 07-10-18, 02:22 PM
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My point exactly. Without even getting into all the elements you have no control over...you're using a Power tap hub, which has an accuracy of, what, +/- 2%? Which means if you're measuring at 300 watts, you might actually be at 294. Or 306. Or anywhere in between. So sure, if you're trying to figure out whether a MTB is more aero than a Tri bike, sure it will work. But is that really helpful? Wind tunnel testing is used for things as minute as which cable routing is more aerodynamic. There's no way riding a bike outside with a 12 watt guess range is going to be able to give you a useful answer to that.
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Old 07-10-18, 02:22 PM
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Originally Posted by Abe_Froman View Post
Not to start an argument....but don't you think lab testing would be more helpful than real world?
As long as it's representative of the real-world behavior, yes. Which aero usually is.

The trick with wind tunnel tests is that things are often tested in isolation, and riders vary. Sometimes one bike appears to be much more aero than another, but once the rider's legs are making the air turbulent in the back half of the machine, much of the advantage falls away.

How could you possibly isolate just aerodynamics in a meaningful way for testing on a moving bike outside a wind tunnel? I have a feeling the margin for error introduced by any number of factors would be greater even than the aero differences you're trying to test. You would never know how 'real' any result is.
The RChung method is surprisingly decent, because it tries to use the real-world variability to inform the result, rather than filter it out as noise. It requires some discipline from the rider and isn't as good as a wind tunnel, but it's a lot cheaper!
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Old 07-10-18, 02:28 PM
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Originally Posted by Abe_Froman View Post
My point exactly.
I think you missed Robert's point. The virtual elevation method can resolve differences about as well as a wind tunnel. One of it's strengths is the ability to identify and discard low quality data.
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Old 07-10-18, 02:30 PM
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Originally Posted by HTupolev View Post
As long as it's representative of the real-world behavior, yes. Which aero usually is.

The trick with wind tunnel tests is that things are often tested in isolation, and riders vary. Sometimes one bike appears to be much more aero than another, but once the rider's legs are making the air turbulent in the back half of the machine, much of the advantage falls away.


The RChung method is surprisingly decent, because it tries to use the real-world variability to inform the result, rather than filter it out as noise. It requires some discipline from the rider and isn't as good as a wind tunnel, but it's a lot cheaper!
Frankly I don't have time to go through 112 pages of it...but it seems like a very interesting exercise in statistics, but a very poor method for designing a fast bicycle.
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Old 07-10-18, 02:34 PM
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Originally Posted by Abe_Froman View Post
... a very poor method for designing a fast bicycle.
People who get paid to design fast bicycles (and components) disagree.
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Old 07-10-18, 02:36 PM
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Originally Posted by asgelle View Post
People who get paid to design fast bicycles (and components) disagree.
Are you saying that frame manufacturers design aero frames using power meter readings rather than a wind tunnel testing? That would be the first time I've heard that.
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Old 07-10-18, 02:41 PM
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Originally Posted by Abe_Froman View Post
Are you saying that frame manufacturers design aero frames using power meter readings rather than a wind tunnel testing? That would be the first time I've heard that.
I didn't say or imply any such thing. It doesn't have to be either/or; the ones I'm thinking of do both.
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Old 07-10-18, 02:42 PM
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Real world testing . . . I've coasted down passes wheel-to-wheel with aero frames while on my fat round tubed conventional bike. Wheel to wheel only lasted a few instants before I coasted away from them. So if people pay you to TT a couple seconds faster per mile, maybe worth it, but larger ears would negate the value. So first use aero covers on your ears and shoes. Seriously, I've never noticed a difference when pass coasting with other riders. Only bike I ever saw that seemed to have an advantage was running 650 carbon 3-spoke wheels and tires to match. We did coast wheel to wheel. Round Ti frame. We know wheels help. Frame not so much. Then again, in that one case, it might have been the Cat II rider, not the wheels at all.
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Old 07-10-18, 02:47 PM
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Originally Posted by Carbonfiberboy View Post
Real world testing . . . I've coasted down passes wheel-to-wheel with aero frames while on my fat round tubed conventional bike. Wheel to wheel only lasted a few instants before I coasted away from them.
So you proved that your propulsive forces were greater than theirs or the retarding forces less. How do you know it was the aero component that was responsible (much less the contribution from the frame)?
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Old 07-10-18, 02:50 PM
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Well I'm faster on my aero bike than I am on my endurance bike... If I really go for it on my endurance bike, I can hit the same speeds, but it just takes a bit more effort. It's probably down to a number of things though, including weight (7.5kgs vs 10.5kgs), position, better gearing options (11 speed vs 8 speed), and, most importantly, I find my aero bike much more fun to ride.
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Old 07-10-18, 02:52 PM
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My fat ass negates any type of aero!
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Old 07-10-18, 03:05 PM
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Originally Posted by asgelle View Post
So you proved that your propulsive forces were greater than theirs or the retarding forces less. How do you know it was the aero component that was responsible (much less the contribution from the frame)?
You nailed it. My point exactly. No propulsive force. Pass coasting. Little noticeable contribution from anything other than rider position, which is free, but takes a lot of work. Yeah, you can buy speed but only in tiny increments. Big rewards in work. Funny how people get that all upside down. Lots of RC threads about equipment, very few (none?) about position.

Sorry to interrupt the discussion but this one in particular . . . I mean real world testing? Really? "Where are your elbows?" would be vastly more practical. I do real world testing.
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Old 07-10-18, 03:13 PM
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Originally Posted by Carbonfiberboy View Post
You nailed it. My point exactly. No propulsive force.
I thought you were going down hill. Wasn't gravity a propulsive force? In other words were the total weights of you and your bike the same as the other person's?
Originally Posted by Carbonfiberboy View Post
Little noticeable contribution from anything other than rider position, ....
And rolling resistance, and drag from clothing, and the frame. and all the components, ...

And I've noted before, no matter how much time you put into your position, if you don't have a bike under you, you're not going anywhere.
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Old 07-10-18, 03:22 PM
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Originally Posted by Abe_Froman View Post
Are you saying that frame manufacturers design aero frames using power meter readings rather than a wind tunnel testing? That would be the first time I've heard that.
That's cuz you don't appear to know what the big manufacturers (like Specialized, Trek, Cervelo, Cannondale, etc.) actually do. They use all three of CFD, wind tunnels, and field testing.
You also don't appear to be familiar with the implications of the Central Limit Theorem.
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