If you have the P2C set up with wheels and bars as good as the P5's, cable routing mod, 3T or later fork, then not much at all. Handful of seconds I'd wager.

My guess is less than 10w if the bike fits well. I'd say it might test similar to the Felt (control bike) that they used in the aero bike shootout: https://www.slowtwitch.com/..._Peak_Aero_6429.html

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Madison photographer Timothy Hughes | Instagram

They got ~.005 CdA difference in that test, or 2-3% of total aero drag for most of us, and <1% in speed: https://drive.google.com/...c2pYSHJ1cVllUjQ/view

And I think a well sorted P2C would fare better than the B series Felt in that test.

On the tririg site they. Post about testing a p2c with their aero bar and brake instead of the stock setup and got pretty much the same drag numbers as a p5....a much less expensive upgrade.

40-50s

That was a new p2, not a p2c.

And the frames were two different sizes. And they had different cockpits. It was not a frame-to-frame comparison.

If you make it look like this it'll be faster than snot off a fried egg.

Arrgh, those shifters, my poor eyes!

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29 years and counting

I upgraded my p2c with tririg alpha x and omega brakes instead of buying new and man is she fast. It’s all about cable management and a clean front end.

There may also be a (potentially substantial) psychological speed boost.

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I do the same thing as them, just slower

that was the point. They were showing that a well set up P2 could be as fast as a stock P5 and potentially at a lower price point.

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I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes

What he meant was the P5 was a larger frame than the P2

For all we know that is the reason the P2 was just as fast and nothing to do with the add ins

Does seem strange to go to all the money and energy to do wind tunnel comparison and use two different size frames

Different geometries so maybe they were still set to the same fit coordinates? It just required a different size of p5 to do so. I don't know, just speculating

The protocol section says the bikes were configured to the same fit coordinates, but there is clearly a lot more plastic in the airflow with the larger P5 frame. Seems like it would have made a crapton more sense to use the same size P2, but the logic for justifying the differences is a bit baffling.

I have a 2008 P3C that I wish someone could clean up with Di2.

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Let food be thy medicine...

Not that baffling: "For our tests with the P5, we used a 56cm bike (just slightly larger than the 54cm P2). Of course, the pad stack/reach were consistent for both setups. Using the larger frame size allowed us to keep the bars slammed for both bikes, and also put each bike's aerobar in the middle of its adjustment range. The P5's integrated Aduro bar does not allow for independent pad stack adjustment, only macro adjustments via the High-V equipment, or micro adjustments via stem spacers. As an alternative, we could have used a 56cm P2 and set up the Alpha X differently, which may or may not have had an effect on the results. However, I prioritized a mid-range bar adjustment, since that would represent a setup that would allow its rider the ability to adjust their position up OR down. In the end, since the positions were the same, and the bars were in the middle of their adjustment ranges, I'm satisfied that it's a very fair and valid test. Again, I present all the information that went into these decisions so that the reader can draw their own conclusions."
https://www.tririg.com/...age=windtunnel_intro

If tall frames are so bad, shouldn't we be getting very low stack frames and add aerobar risers to taste?

Yes. That test was apples-and-oranges because of the two different frame sizes. Nick's statement "In the end, since the positions were the same, and the bars were in the middle of their adjustment ranges, I'm satisfied that it's a very fair and valid test" without any science to validate it is the baffler. He should know that he gave the P2 an aerodynamic advantage.

But your reasoning implies that we should all be on low stack frames, because adding height to aerobar risers is more aero than a taller headtube. Is this true?

About how many cm^2 of extra frontal area do you think the P5 has vs the P2 in the test, and what would be the approximate Cd of this added area?

Yes, generally this is true. There have been a number of threads on ST to this effect. But, it is within reason, because the bike has to fit and be functional for its rider. For example, if you picked a frame two sizes too small, you might need a crazy long stem and extra long seat post. You cannot arbitrarily pick a frame size without other impacts.

But, the above is moot. Cervelo geometries are the same for P2 & P5. There was no functional excuse to test two different size bikes. If Nick was really going for a true frame-to-frame argument, he would have tested the same size. But, he did not have two bikes of the same size, so he wiffed it. Also, we do not know to what extent the P5's Aduro cockpit contributed to the drag difference. Best Case, the test may have made an argument that the Alpha X is more aerodynamic than the 3T Aduro. I get that he could not test everyhting, but without any controls, and two different frame sizes, and two wholly different cockpit configurations, the results are mush.

Caveat: I have a lot of Tririg stuff, and I totally love it. I am not a Tririg hater, just a hater of that silly test and its false conclusions.

Pics of your setup?

Sorry needed to resize them.

That looks great. I have a 2012 P2 (the black and white frame) and am considering doing this same thing with it rather than upgrade to an entirely new bike.

I have two P2s size 54 One each for where I am in different parts of the country different times if the year

I’m thinking of getting a P5. Would you recommend I get a size 56?