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P4 Drag Numbers
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Andrew69
Sep 27, 08 16:50
Post #1 of 208 (5279 views)
P4 Drag Numbers
Can't Post
Here is a scan of the numbers as supplied by Cervelo
Let the games begin!
(This post was
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sergio
Sep 27, 08 16:54
Post #2 of 208 (5259 views)
Re: P4 Drag Numbers [Andrew69]
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where is trek ttx?
maybe their white paper was right after all
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Sérgio Marques
When it hurts is when it feels good ;-)
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(This post was
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Dr. J
Sep 27, 08 16:55
Post #3 of 208 (5257 views)
Re: P4 Drag Numbers [Andrew69]
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curious re: the absence of the TTX.
Any thoughts?
Jeff Shilt
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ShawnF
Sep 27, 08 16:56
Post #4 of 208 (5252 views)
Re: P4 Drag Numbers [Dr. J]
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Maybe the Trek White Paper was valid...
shawn
nuun active hydration
Tom A.
Sep 27, 08 16:59
Post #5 of 208 (5241 views)
Re: P4 Drag Numbers [Andrew69]
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Where's the P1?
Tom A.
Sep 27, 08 17:01
Post #6 of 208 (5235 views)
Re: P4 Drag Numbers [Andrew69]
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Oh...and does anyone know if the positive yaw direction is with the wind hitting the DS or NDS?
Tom A.
Sep 27, 08 17:02
Post #7 of 208 (5229 views)
Re: P4 Drag Numbers [Andrew69]
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....it also looks like the reported "30s over 40K vs. a P3" is slightly conservative ;-)
Tom Demerly
Sep 27, 08 17:05
Post #8 of 208 (5210 views)
Re: P4 Drag Numbers [Andrew69]
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The TTX is missing and I'd be interested to see it in the mix.
http://www.bikesportmichigan.com/
(NOTE: This poster owns a retail business selling triathlon related products).
sergio
Sep 27, 08 17:06
Post #9 of 208 (5208 views)
Re: P4 Drag Numbers [Tom A.]
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where is the hotta, lotus and hooker :P
=====================================
Sérgio Marques
When it hurts is when it feels good ;-)
Sergio-Marques.com
=====================================
YAMA
Sep 27, 08 17:06
Post #10 of 208 (5208 views)
Re: P4 Drag Numbers [Andrew69]
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Interesting. Forgive my ignorance, but why do you suspect the numbers for negative and positive angles beyond 5 degrees are so asymetrical (different) for the P4 while most other frames seem fairly symmetrical? Do the negative degree numbers represent the non-drive side or drive side of the bike? Also curious why numbers don"t go up to 15 degrees on both sides.
2008 Zoot Ultra Triathlon Team
Tom A.
Sep 27, 08 17:11
Post #11 of 208 (5189 views)
Re: P4 Drag Numbers [sergio]
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where is the hotta, lotus and hooker :P
Can't help you with the hotta, and Andy's posted numbers on the Hooker...but this (the top plot) shows the Lotus:
gtingley
Sep 27, 08 17:22
Post #12 of 208 (5142 views)
Re: P4 Drag Numbers [Tom A.]
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....it also looks like the reported "30s over 40K vs. a P3" is slightly conservative ;-)
at 8deg yaw on the chart, what would you estimate based on the numbers above, P4 vs P3 over 40k?
- Gary
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Tom A.
Sep 27, 08 17:40
Post #13 of 208 (5096 views)
Re: P4 Drag Numbers [gtingley]
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In Reply To
....it also looks like the reported "30s over 40K vs. a P3" is slightly conservative ;-)
at 8deg yaw on the chart, what would you estimate based on the numbers above, P4 vs P3 over 40k?
By my "eye"...average of +/- at that yaw looks to be ~45s over 40K...assuming these drag values are measured at 30mph (I REALLY wish they'd just report the values as "CdA" or "CxA" so we wouldn't have to worry about the speed, air density, etc....OK, rant off ;-)
MOP_Mike
Sep 27, 08 17:43
Post #14 of 208 (5081 views)
Re: P4 Drag Numbers [gtingley]
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....it also looks like the reported "30s over 40K vs. a P3" is slightly conservative ;-)
at 8deg yaw on the chart, what would you estimate based on the numbers above, P4 vs P3 over 40k?
Eyeballing the chart and averaging the L/R figures at ~8 degrees...lets call it 100g reduction. Using AC's ROT, that's about equal to 40 seconds over 40K.
EDIT: Thanks, Tom...I guess you can beat me at a typing race, too. ;)
"...if you are pedaling correctly, it doesn't matter what cranks are on your bike." -- Frank Day
(This post was
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by MOP_Mike on Sep 27, 08 18:02)
Francois
Sep 27, 08 17:44
Post #15 of 208 (5079 views)
Re: P4 Drag Numbers [sergio]
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And most importantly, where is the rider? ;-)
Francois
Sep 27, 08 17:50
Post #16 of 208 (5055 views)
Re: P4 Drag Numbers [Andrew69]
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I remember someone said the cheetah was a fat pig in the tunnel...any data?
gtingley
Sep 27, 08 17:55
Post #17 of 208 (5042 views)
Re: P4 Drag Numbers [Tom A.]
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~45s over 40K...
That's pretty much hitting the "20%" mark, I'd say.
Probably would not hurt to use the structural fairing instead of the bottle.
- Gary
Rotor Q-Rings - Slowtwitch exclusive 15% discount on sets of Q-Rings
. Use code "slowtwitch" online at checkout at
http://www.RotorCranks.com
, all items in stock, and always FREE UPS Ground shipping!!
Mito Chondria
Sep 27, 08 18:03
Post #18 of 208 (5015 views)
Re: P4 Drag Numbers [Andrew69]
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Thank you very much for sharing this data with us. Now that they did most on the engineering work on another great product they hopefully still have some time left for a "the first ever" sexy Cervelo paint job ;)
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Drinyth
Sep 27, 08 18:09
Post #19 of 208 (4988 views)
Re: P4 Drag Numbers [Andrew69]
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Thanks for sharing. I, too, would have liked to have seen the TTX on there for comparison sake.
Also, the P2 is one hell of a value based on the below graph! It's around 1/2 the price of the P3 (frameset) and just a fraction less aero.
Tom A.
Sep 27, 08 18:10
Post #20 of 208 (4987 views)
Re: P4 Drag Numbers [gtingley]
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Hehe...that "bottle" has me thinking of a "cozy" I could put on my Bonty Speed Bottle on the P2K...of course, it's only "purpose" there will be insulation for the bottle. You know, to keep the contents cold ;-)
ttx_tri
Sep 27, 08 18:13
Post #21 of 208 (4976 views)
Re: P4 Drag Numbers [sergio]
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I was wondering the same thing. I guess taking the biggest threat away from the P4 you can make the numbers look good.
Proud seller of 39 items in the ST classifieds so far
MITaerobike
Sep 27, 08 18:16
Post #22 of 208 (4967 views)
Re: P4 Drag Numbers
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More than anything, I'd like to see all of the bikes pictured as tested. Does anyone know how the bikes were tested (i.e. w or w/o disc wheels, cables?, P4 tested with bottle, etc.)?
It's easy to see 50-150 gram differences in the tunnel due to stem variations, steerer lengths, etc.
And an additional repeat of one or more bikes would be great too.
Looks like the frame and fork are a huge improvement over the P3C, no doubt. I bet they gain 75-100 grams of drag just from improved tube shapes (especially the fork).
Mark
ksull
Sep 27, 08 18:20
Post #23 of 208 (4955 views)
Re: P4 Drag Numbers [Andrew69]
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I want wind tunnel numbers for
TTX, Specialized Transition, Look 596 throw a Ceepo in there too
if some one dose this they will be my hero.
Kerry Sullivan
USAT,USACII, CSCS, NLP practitioner
http://www.BlazingTriSpeed.com
Tom A.
Sep 27, 08 18:22
Post #24 of 208 (4947 views)
Re: P4 Drag Numbers [MITaerobike]
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More than anything, I'd like to see all of the bikes pictured as tested. Does anyone know how the bikes were tested (i.e. w or w/o disc wheels, cables?, P4 tested with bottle, etc.)?
It's easy to see 50-150 gram differences in the tunnel due to stem variations, steerer lengths, etc.
And an additional repeat of one or more bikes would be great too.
Looks like the frame and fork are a huge improvement over the P3C, no doubt. I bet they gain 75-100 grams of drag just from improved tube shapes (especially the fork).
Mark
I agree...that would be great. What you touch on above shows just how easy it can be to "sandbag" a particular model in the testing, even if it's their own ;-) Anyone besides me think the "fixed offset" of the P2C vs. the P3C is a bit too
convenient
??
Then again, I guess we're lucky to see this data in the first place...
Another thing nobody has commented on is the conspicuous absence of the Transition in that chart. Mark, do you have any input on where that bike would stand in the mix?
MOP_Mike
Sep 27, 08 18:24
Post #25 of 208 (4942 views)
Re: P4 Drag Numbers [YAMA]
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Interesting. Forgive my ignorance, but why do you suspect the numbers for negative and positive angles beyond 5 degrees are so asymetrical (different) for the P4 while most other frames seem fairly symmetrical? Do the negative degree numbers represent the non-drive side or drive side of the bike? Also curious why numbers don"t go up to 15 degrees on both sides.
Just guessing here...but I'd bet that the water bottle partially shields the crank when the wind is from the non-drive side.
"...if you are pedaling correctly, it doesn't matter what cranks are on your bike." -- Frank Day
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