If this were the case, then why would they not release a detailed testing protocol? Failure to provide data is always a bad thing.
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Re: Kestrel Wind tunnel data [Dave Luscan]
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If this were the case, then why would they not release a detailed testing protocol? Failure to provide data is always a bad thing.
Re: Kestrel Wind tunnel data [Andrew V]
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steve h (sharad here) promised us at the show that they would publish the details and as TomA mentioned be as transparent as possible.
He did say he was looking forward to the st thread on the topic, so I assume he is watching this (hi steve!) and will chime in eventually...
G
greg
www.wattagetraining.com
Re: Kestrel Wind tunnel data [Dave Luscan]
[ In reply to ]
Then how does one explain the extremely high drag for the P3? The only answer that really makes sense (and is consistent with both Steve H.'s interview and the description on the graphic from xtri.com) is that it was tested with stock wheels.
BTW, does anyone know if the 4000 is UCI legal? I've received conflicting opinions...
Re: Kestrel Wind tunnel data [Dave Luscan]
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But . . . but . . . but . . . Dr. Coggan implied otherwise!?!
Re: Kestrel Wind tunnel data [Dave Luscan]
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""things were done very fairly to all bikes in the test"
Fairly is a relative term, depending on the philosphy used during the testing. Most companies are controlling out the non-proprietary gear to the greatest extent possible. In the absence of information about the specific setups on the bikes in the graph, and given the statement about essentially stock bikes, Kestrel appears to have changed that philosophy to be able to say "Look, the bike we give you at our MSRP is faster than the bikes these others give you at their MSRPs." (I'm still holding out that even if they took that tack, they would at least control out the wheels since those are the most likely suspects to be changed out by consumers in a race situation...and since, as others have noted, deep aero wheels vs stock aluminum clincher wheels leads directly to complete non-sequitur with this data set).
If that is, in fact, the case, as a consumer, I can appreciate that approach...even if the engineer in me wants to crawl down into the weeds and demand a complete apples-to-apples approach, since I'm unlikely to buy a stock bike anyway. I mean...take a look at any P3-infested transition area. By and large what you'll find are stock P3s with some Zipps, Heds or somesuch for wheels. Same with Spec transitions, Felt DAs, etc. So apparently, the average consumer isn't inclined to take the time to dig into each and every part of a bike's setup to determine the efficacy of the system. All they are concerned with is which of the bikes is going to be faster when they stick their Zipp 808s on it. That involves the entire system, not just the frame and proprietary fork, seatpost, headset, and/or stem.
Just a loose thought train... while I take a break from the engineering weeds here at work! ;-)
Fairly is a relative term, depending on the philosphy used during the testing. Most companies are controlling out the non-proprietary gear to the greatest extent possible. In the absence of information about the specific setups on the bikes in the graph, and given the statement about essentially stock bikes, Kestrel appears to have changed that philosophy to be able to say "Look, the bike we give you at our MSRP is faster than the bikes these others give you at their MSRPs." (I'm still holding out that even if they took that tack, they would at least control out the wheels since those are the most likely suspects to be changed out by consumers in a race situation...and since, as others have noted, deep aero wheels vs stock aluminum clincher wheels leads directly to complete non-sequitur with this data set).
If that is, in fact, the case, as a consumer, I can appreciate that approach...even if the engineer in me wants to crawl down into the weeds and demand a complete apples-to-apples approach, since I'm unlikely to buy a stock bike anyway. I mean...take a look at any P3-infested transition area. By and large what you'll find are stock P3s with some Zipps, Heds or somesuch for wheels. Same with Spec transitions, Felt DAs, etc. So apparently, the average consumer isn't inclined to take the time to dig into each and every part of a bike's setup to determine the efficacy of the system. All they are concerned with is which of the bikes is going to be faster when they stick their Zipp 808s on it. That involves the entire system, not just the frame and proprietary fork, seatpost, headset, and/or stem.
Just a loose thought train... while I take a break from the engineering weeds here at work! ;-)
Re: Kestrel Wind tunnel data [ndenezzo]
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Re: Kestrel Wind tunnel data [TriBriGuy]
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Assuming (always a dangerous thing) that was indeed their thinking and how the bikes were tested, then it would also only be fair to list the MSRPs:
Kestrel 4000 LTD: $10829
Cervelo P3: either $3600 or $4500 depending on spec
So IOW, you could buy two Ultegra-equipped P3s and a set of Zipp race wheels for the price of the Kestrel, have one bike for training and one just for racing, and likely not give up anything in the aero drag department...
Last edited by:
Andrew Coggan: Oct 8, 09 7:44
Re: Kestrel Wind tunnel data [Tom A.]
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You've seen a 4000 in person, Tom?
Re: Kestrel Wind tunnel data [TriBriGuy]
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Yup...touched it too...while I was standing next to, and conversing with, Steve Harad :-)
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [hgrong]
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It was actually ATC who first suggested that perhaps the bikes weren't fitted with the same wheels:
http://forum.slowtwitch.com/...post=2534689#2534689
All I've said is that explanation makes sense given the high drag for the P3, the statements on the original graph, and Steve Harad's interview on xtri.com. If there is some other logical explanation, then I'm all ears...
Re: Kestrel Wind tunnel data [Dave Luscan]
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I guess that all depends on your (or the birdie's) definition of "fair"...
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Tom A.]
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Re: Kestrel Wind tunnel data [Andrew Coggan]
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Trust me, if you see how most of my projects around my house have been turning out lately...you'd start calling me the "anti-Midas" :-)
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Tom A.]
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Re: Kestrel Wind tunnel data [gregclimbs]
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Yeah...he DID say he somewhat enjoyed spinning up us "propeller heads" a bit, didn't he? Hi STEVE! :-P
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Tom A.]
[ In reply to ]
Doesn't that version of the Fuji come with high-zoot aero wheels? Based on the data, I'd expect it to have been tested with wheels similar to those on the P3.
Re: Kestrel Wind tunnel data [Andrew Coggan]
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Yup...1080s...that's why I guessed that one. Has any other data you've seen on the D6 been "bike only" (like apparently this data is)?
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Tom A.]
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Re: Kestrel Wind tunnel data [Andrew Coggan]
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There is absolutely no way that they bikes were tested with different wheels. It IS entirely possible that they were tested with the wheels that made the Kestrel bicycles look the best, but surely they were identical across the 4 models.
On the topic of the Cervelo data on the P3 vs Airfoil, I suspect that was done with the 2008 model of Airfoil, so the only constant between this new test and the Cervelo data is the P3 itself. Unfortunately that hasn't left us with much to go on.
Chris
On the topic of the Cervelo data on the P3 vs Airfoil, I suspect that was done with the 2008 model of Airfoil, so the only constant between this new test and the Cervelo data is the P3 itself. Unfortunately that hasn't left us with much to go on.
Chris
Re: Kestrel Wind tunnel data [Andrew Coggan]
[ In reply to ]
Judging by the width of that seat tube/brake area, along with the "truncated" back half...oh, and also that silly behind the fork brake (with the attendant brake housing hanging out in the breeze)...well, yeah...let's just say I wouldn't expect it to be close to a P3C with the SAME "low line" wheels on both ;-)
http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Andrew Coggan]
[ In reply to ]
--------------
Frank,
An original Ironman and the Inventor of PowerCranks
Re: Kestrel Wind tunnel data [chicanery]
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Ummm...how do you square your opinion with this quote from Steve Harad (bold added)?
Quote:
Well, we are going to put the wind tunnel data out shortly and Xtri will get the information right after Interbike.. Just know that we not only tested 20% faster then the Cervelo P3 and we also believe we have come up with the standard on testing. The concept is that I want to test bike vs. bike. Exactly how the consumer gets it. No cheating. It is helpful to the consumer to see what the bike on the floor of the bike shop tests, not just the frame or a partially assembled bike.http://bikeblather.blogspot.com/
Re: Kestrel Wind tunnel data [Tom A.]
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Re: Kestrel Wind tunnel data [Andrew Coggan]
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