The tunnel time alone was $3,600. The Cervelo P5-X stem quill and seat post were $600.

I don't think I need to go into the rest of the expenses. But they were material.

Still good for the Premier Tactical as it's the cheapest of the bunch, excluding a used Felt.

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--Chris

What's interesting is that there isn't really a bike that performs well at low yaw without also performing well at high yaw. With your testing protocol, fast is fast.

I don't half want bike 1 to be the Felt. I suspect it will be the Ventum.

Edit.. I wrote 6 instead of 1.

So you put a lot of thought into it and came up with the wrong answer?

I'm guessing the only one I'd buy is a Premier Tactical cuz it's the nicest looking.

Yes, I'm thinking the big ass seat tube of the ventum is causing drag on that side of the graph, thus my prediction... :)

I'll pick the P5 as the fastest.

But why would that be asymmetric?

1. Andean
2. Ventum
3. P5X
4. P5
5. Premier
6. Felt

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

Dunno, that's just my guess!

Wrong answer for you? Yes.

Grams of drag at 30 mph is used by nearly every manufacturer that does or has done comparison testing. Regular people are reading this report, not just armchair aero quants. Like my sister, who did her first half Ironman last year and rides an alloy Novara.

I have no problem publishing the CdA values outside of the report, but for the purpose of the report, it needs to be accessible to a broad audience

What would you want on the y axis? CdA? I've thought about this a bunch of times and I can't think of a significant benefit over the other. What am I missing?

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blog

HOW ARE WE SUPPOSED TO GUESS WHEN THE AXES AREN'T LABELED?!?!?!

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Any run that doesn't include pooping in someone's front yard is a win.

Yes. Because it's the one unit that doesn't require additional test information to be useful.

"Grams of drag" is not only a misuse of units (drag is measured in force, not mass), but it requires additional information (such as test air speed and air density)...and then most consumers of the data will STILL need to "translate" it into some other meaningful unit or speed for context. Yes, Kiley said "at 30 mph", but many times I've seen that key info not be related upon repetition/other distribution, plus it adds to the confusion of "but I don't ride that fast", etc. Edit: And then there's the problem of manufacturers deciding to test at lower tunnel speeds (ostensibly to be more "realistic", but really to show low gram values) and then not being overly diligent about pointing out that speed difference. It just all adds to confusion.

Yeah "grams of drag" has been the most common units used in reporting this type of data, but that's no reason for continuing its use if there's a better and more clear alternative. All of the above is why Specialized has switched to showing their drag charts in CdA.

Or...you can just report the CdA and allow the user to directly "translate" it into their conditions of interest. Plug in your air speed and density of interest and go. Least steps and chance for misunderstanding.

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http://bikeblather.blogspot.com/

Don't you hate it when people provide well thought out, logical answers to questions on the internet?

Thats all great Tom. I'm sure Kiley will give you exactly that and you and a few others here will do all the data masturbation you want.

But this is going in Triathlete mag. Not everyone has dentists for parents. They're not going to be plugging anything into anything.

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"One Line Robert"

The asymmetrical result is odd in this test. Would only have expected that on a bike with one chainstay or a MTB style single fork ("Lefty") or something else large and asymmetrical. Disk brakes can be seen in the data and the chainrings but that's pretty small.

So...tell me, how are they going to be using "grams of drag at 30mph"?

How will they put it into context for themselves? Explain to me how that's somehow more useful??

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http://bikeblather.blogspot.com/

For example, in Velonews today it was reported that the new Cervelo R5 has "a claimed savings of 44 grams of aerodynamic drag over the previous R5 frame"

That's what I'm talking about...no mention of test speed or air density. No context. WTF does that even mean??

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http://bikeblather.blogspot.com/

Hello kileyay and All,

Please refresh my memory ...... was the yaw sweep 15 degrees each side?

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Cheers, Neal

+1 mph Faster

It means nothing to you. We're well aware. I also don't disagree with you, btw.

But why is it so hard for you and others to be self aware enough to understand that it doesnt matter to most end consumers? Give them a graph or number with some sort of rank order that provides context to the relative improvements over each bike, and thats enough (right or wrong - thats not the argument here). Do you think 90% of this sport is talking about air density and speed as it relates to this type of testing? If so, I'd say it'd be in your best interest to spend less time on ST.

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"One Line Robert"

New album cover for the upcoming 35th anniversary release of Pink Floyd's "Dark Side of the Moon" ?

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"They're made of latex, not nitroglycerin"

Tom,

I don't know what the audience of this report is, nor do I know the breakdown in quant aero sophistication of the 120+ people who contributed to the GoFundMe.

What I do know is this:

• Grams of drag is easier to observe on a chart; easier to convert on a rough basis into "watts", which is the term I'm betting *most* people understand; and consistent with nearly every other study of this type ever done
• The journalist I spoke with from Triathlete magazine could not conceptualize anything other than minutes over an Ironman, and basically said "la la la la" when I tried to talk through the caveats
• Before undertaking this study, I could not have answered the question stevej asked, and I sure as shit couldn't tell you the equation for CdA
• Specialized publishes the vast majority of their 'studies' on YouTube in seconds over 40k

Here's the context given in the rough draft of the report:



Feel free to help me out with something better

And don't worry, there is a very quick segue into an explanation on why time-distance assessments require much more intense and *individual* quantification. And then we go ahead and step you through that.

10 degrees

And yet, invariably when reports like this are produced there's a cavalcade of folks asking "what does this mean to my split time?"

Sounds like there might be better ways of contextualizing the information, no?

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http://bikeblather.blogspot.com/