Speaking of which, how is the fit and bike working out on the P3C-Track?
Right…
The big point here, at least to me, is the DIFFERENCE between the “aero-ness” of one TT bike vs another…
It’s not like the 2007 Colnago bike is a bad bike, or is suddenly NOT aero at all. It’s just slightly less aero than the Cervelo.
So, - if the bike, with it’s ultra cool carbon Zipp wheels, and it’s super awesome Hed aero bars, accounts for 15% of one’s overall aero, - what do you think the total aero difference will be between an already nice aero Colnago frame and super duper new tech Cervelo aero frame?? My contention is that it is very slight. When I said “no” difference, - I meant no appreciable difference in overall results at the end of someone’s time trial. Apologies if I didn’t make that clear, or spell that out. And, - I definitely deserve to be called to task for not being more clear.
The point here is that the “REAL” aero numbers of the two frames come down to an insignificant part of one’s overall time trial.
It’s not false advertizing on Cervelo’s part, - I’m sure that they make a good TT frame. But, there’s a good deal of marketing hyperbole here, - and the term “better” bike is a big, big, moving target, where many factors come into play. For example, - and this is just speculation, - maybe the Colnago TT frame that Rasmussen rode is a bit stiffer and more of his power gets translated into spinning that rear disc. If true, and again it’s completely speculative, - that stiffer Colnago frame may be “faster,” - even though it is slightly less aero…
“a well-designed aerodynamic frame provides significant benefits”
Andy, can you share some of the wind tunnel data? I’m very interested in understanding what you consider “significant”. For example, is it reasonable to expect that someone switching from a QR Kilo or a Colnago C-50 Krono to a Cervelo P3C - everything else being equal - would cut .5 lbs from their drag, like Tom suggested? My guess would be “no”, but I would like more info.
"the Colnago TT frame that Rasmussen rode "
You mean the Giant that Rasmussen rode… Of course, don’t forget that Rasmussen also used a box rim in the front and may have been using boosted blood - lots of strangeness surrounding the Chicken’s run.
I can only speak for myself when I say that I’m not really interested in your idiosyncratic speculations…
If you like, you can substitute Colnago for Giant, for Pinarello, - if you want to keep going sideways…
“a well-designed aerodynamic frame provides significant benefits”
Andy, can you share some of the wind tunnel data?
The three most extensive datasets that I’ve seen are:
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the tests that Chet Kyle conducted and described in Cycling Science;
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the tests conducted for Project 96; and
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the well-known aero bike “shoot-out” for which Colby Pearce served as the test subject, and which were described by Lennard Zinn in VeloNews.
As indicated, #1 and #3 are in the public domain, so I’ll leave it up to you to track them down. As for #2, I believe that I’ve cited some of the numbers before, so searching for prior posts by me on this topic should turn them up.
Speaking of which, how is the fit and bike working out on the P3C-Track?
Quite well, actually: Angie clocked a 56:53 on it at the Missouri state TT, which was a new course record by >4 min and was >7 min faster than 2nd place - in fact, out of ~150 starters only seven men were able to beat her time.
How was your Ironman?
I’m not surpirsed that a bunch of bikes with 3:1 aspect ratios, tight fitting rear wheel cutouts and narrowed head tubes perform similarly.
What I would be curious to know is if you threw a Scott plasma, a Planet X, heck even an old Cannondale or a Qunitana Roo into the mix. Look at what less than ideal bikes look like with and without a rider.
Gerard himself has acknowledged that Walser, the P3c, the P2c, Trek’s TTX are all similarly performing bikes. But he also has hinted at the fact that after these bikes theres a drop off to the P2sl and after the P2sl there is another significant decline in performance of bikes aerodynamically, both with and without a rider in the tunnel.
So tell me… you being schooled by 4 minutes by your wife… what effect did that have in the household? 
tests of riders on aero and non-aero frames: how much has really been done to control the positioning of the rider? Identical rider? Identical position? Identical equipment?
Ah-yup (perhaps it’s time for you to dig through, e.g., old issues of Cycling Science to truly appreciate what has been done before).
what Andy is trying to say is that Chet Kyle showed that the differences in bikes measured in the tunnel DO IN FACT scale to bike+rider in the tunnel.
And what Tom is saying is that he, Andy, Jens, myself and the rest of us anal-retentive-equipment-selectors have also been able to tease these differences out from on the road field tests (that support the tunnel data).
These discussions always devolve like this and it makes me laugh.
g
what do you think the total aero difference will be between an already nice aero Colnago frame and super duper new tech Cervelo aero frame?? My contention is that it is very slight.
Again, the data say that you’re wrong.
So tell me… you being schooled by 4 minutes by your wife… what effect did that have in the household?
None, really: I did the TT pretty much as a lark, and knew going in that I wouldn’t be able to beat her. (I did, though, produce 4% more power than she did. )
I’ll have to apologize for the quick hi-jack…
But, that is a smoking time for Angie, give her my congratulations.
as for Ironman, well… I had a wonderful vacation, but didn’t get to race due to back issues.
what do you think the total aero difference will be between an already nice aero Colnago frame and super duper new tech Cervelo aero frame?? My contention is that it is very slight.
Again, the data say that you’re wrong.
if toenail is so screwed up and your “data” is right , why are cervelo p3c’s BOP all the time? i know, it’s because their successful marketing programs gropes stupid triathletes who think they will fly once they shell out $5k. everyone is happy now; BOP, cervelo and those not BOP riding something besdies a cervelo.
if toenail is so screwed up and your “data” is right , why are cervelo p3c’s BOP all the time?
To use Tom’s analogy: because they’re powered by Pinto-sized motors. Put a decent-sized engine on one, and it’s a whole 'nother ballgame.
???
Huh?
who? Hope that you weren’t referring to me…
Or did you not understand the concept of a bit less than 15%?
yeah I know, - the CSC engines were firing on all cylinders during the tour, - right?
Or did Cervelo make the Trek and BMC frames…???
yeah I know, - the CSC engines were firing on all cylinders during the tour, - right?
Well, Cancellara’s certainly was during the prologue - or have you forgotten his victory already? 
Time to jump in!
I actually agree somewhat with toenail. What he’s been citing about studies in MIT are quite correct: we do fine that frames don’t play a very important role in terms of aerodynamics apart from getting you to fit well on the bike.
Drag numbers of about 1.3-1.4 are currently typical of the top end aero bikes. The DA, P3C, Trek and Specialized all test very close to each other in about that range (we even tested the latter 3 with identical setups).
Once we put a rider on, all the differences practically vanished. Playing around with rider positioning on an aero bike, we can drop a person (and his bike) down from 6 pounds of drag to 5 pounds of drag pretty easily; Me and Mark register about 4.5 pounds of drag, and we both ride conventional P3s.
However, you can’t say that because the bike with rider registers 4.5 pounds of drag, the bike registers about 1.5 pounds of drag, the bike takes up 1/3 of the total drag. It doesn’t add up. The rider hides himself between a few parts of the bike, but a lot of the bike’s rear is effectively faired by the rider. Most of the aero differences between bikes on the rear 2/3rds of the bike become negated once you put a rider on, including stuff like disc wheels and rear hydration systems.
The most dramatic difference we registered was when we tested a saddle mounted hydration system. Without the rider, it contributed to an additional 0.2lbs of drag (out of 1.6+ lbs, quite a significant contribution). However, put the rider on, and that difference completely disappeared.
Between tests of riders on aero and non-aero frames: how much has really been done to control the positioning of the rider? Identical rider? Identical position? Identical equipment?
Thanks for the input chewy.
I’ve got a related question for you. Based on some of the things I’ve seen about the MIT tunnel testing, it’s not clear to me if you do your testing over multiple yaw angles or just at zero yaw. Can you tell us the typical protocol when testing a rider? Thanks.
“a well-designed aerodynamic frame provides significant benefits”
Andy, can you share some of the wind tunnel data? I’m very interested in understanding what you consider “significant”. For example, is it reasonable to expect that someone switching from a QR Kilo or a Colnago C-50 Krono to a Cervelo P3C - everything else being equal - would cut .5 lbs from their drag, like Tom suggested? My guess would be “no”, but I would like more info.
Hmm…well, data that Dr. Coggan revealed here on Slowtwitch implies that the difference between a P2K-like frame and a P3C-like frame is on the order of .015-.020 m^2 of CdA WITH a rider on board. That’s ~0.3-0.4 lbs of drag difference right there.
http://forum.slowtwitch.com/...rch_string=;#1344248
So, if the 2 bikes you listed above are aerodynamically equivalent to at least a P2K, then it’s close to the “up to 0.5 lbs.” I alluded to (which BTW, was between the Hooker and other TT frames of the same era). Based on the statements of Gerard, however, assuming that those 2 frames you list above are equivalent to a P2K may be a bit of a stretch.
I’m sticking with the “up to 0.5 lbs” statement