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1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero
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On the Zinn thread- talking about lighweight and Aero- there's a link to a post on the Cervelo forums by Gerard- talking about a 1.5% savings going from a standard to aero road frame.
http://forums.cervelo.com/forums/t/3192.aspx (about 2/3 of the way down).


"When you do the testing thoroughly, you notice not surprisingly, that the rider is the biggest factor (around 80%). So just like with the weight situation, the rider is the biggest chunk. The rest is then divided in wheels, frames, etc, etc. In the end, the difference between a "normal" frame and an S2 is around 1.5% of the overall drag. Not a huge amount, so it is easy to see why the engine is still the most important (heck, if it wasn't, do you really think Phil and I would support pro riders, instead of winning the Tour de France ourselves?)"
"So obviously, that 1.5% is not that much, but it's more than the 0.2%. And in most riding conditions, total aero related drag is much bigger than weight related drag, so it's much better to save 1.5% of a big number than 0.2% of a small number. " Gerard .Vroomen.

So- comparing an aero frame like the S2 vs R3 saves 1.5% (let's assume bikes/frames weigh the same for this discussion)- does this mean that if a rider going 40 km speed on 'flat/rolling terrain at 300 watts on the R3 would go the same speed on an S2 at 295.5 watts (a savings of 1.5%)? Or is that 1.5% from just the frame drag- and if the body is 80% and the bike is 20%- is it really 20% x 300 watts = 60 watts on the R3 and then 60 watts x 1.5% savings = 59.1 watts needed on an S2: for a savings of .9 watts? by the way: .9 watts = 2-3 seconds over 40km.

This leads to other questions- are the savings really that disappointingly small between an aero road frame- vs a "normal' frame? - range of 1-4.5 watts in example of above? I don't think Cervelo has ever posted their drag data of their aero road frames- but can you assume it's pretty close to the P3C/P2C? Gerard- feel free to chime in on S2 or S3 drag- with comparable tests to the list below (to compare apples to apples)

"Finally, although it's often not possible for riders to say this in public, we notice that both riders who switch on to a Cervelo aero bike and those who switch off it usually comment that they notice a difference. Of course, it's that latter group that would probably be the most convincing for enthusiasts, but that's also the group that can't talk about it. All I can say is that the pros know it works, and that many teams push their bike sponsors to deliver them aero road bikes. Of course, in many cases these aero bikes won't actually be very aero, but the teams won't have any way to verify this (in that respect, they have the same problem as regular consumers, unfortunately)."
Gerard V.


1 watt saved is equal to about 2-3 seconds over a 40km course. So is the difference between an aero road frame and round road frame- just 2-3 seconds to 9-13.5 seconds per hour????

Now if you were set up in a road position on a P3C/P2C- how much more aero- if at all- would you be than a S2/S3- 1 watt? 2 watts???

Interesting (Cervelo Produced) data about TT frames- makes the above information more confusing:
. 9 grams of drag = approximately 1 watt

P3C = 690g of drag for a size 56 bike
Trek TTX = 690
P2C = 705g
Pinarelo = 705
Felt DA = 725
QR Lucero = 735
Kestrel Airfoil = 760
Kuota Kaliber = 780
Guru Crono = 790
Scott Plasma = 800
Orbea Oro = 810

Comparing the Oro TT bike versus the P3C- is 120 grams of drag- so that's a 13.33 watt difference between / among aero TT frames (this is a sizeable difference- about a 27-40 second difference for a 40km). Yet there an only a 1 to 4.5 watt difference between a totally regular round normal tube frame versus the highly sophisticated (best in class???) aero S2 frame? Something doesn't add up... I mean if you could get a cheap custom steel frame that put you in a proper TT position- it would ??seem?? to be much more aero than the less aero TT frames- from Orbea, Scott, Guru, Kuota, etc... I mean- to have 13.33 watt difference just in the same class- TT frames... versus a super aero looking S2 versus a totally traditional bike... you would think the S2 would be more than 13.33 watts better than a totally non aero/normal frameset... Or is it truly- the best minds, best engineers, hours of wind tunnel data- only get 1-4.5 watts better that a circa 1960s-2000s double diamond normal steel/carbon/ti frameset- which might be better than some poorly designed TT rigs, to boot?!? I'm not saying I don't want the watts, but... Clarifications would be great to the logic above....

full disclosure- I own a P3C...
Last edited by: mlinenb: Feb 27, 09 20:42
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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Remember, a big engine and strong legs are always faster then the difference in TT bike drag numbers, there are way to many example results that show this fact.
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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I certainly could be wrong, but when he says, it seems pretty clear that he means 'overall drag', including the rider. Obviously, the smaller the rider, the bigger the percentage. As I said on that thread, the difference is pretty small (and when you factor in sitting in a pack, where wind resistance is reduced 30-40%, that 4-5 watts becomes 1-2 watts).

Still, it all adds up--and most often the most critical moments in a race are whey you're getting the least draft.

As far as your other question, I suspect 2 things: the Cervelo road bike isn't nearly as aero as a P2/P3, and a round tubed bike is better than the worst TT frames (and almost all giant-tubed road frames).
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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I think this was already talked about this morning: http://forum.slowtwitch.com/...;;page=unread#unread

And it really does not apply to triathlons unless you are a drafter.
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [Raptor] [ In reply to ]
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In Reply To:
I think this was already talked about this morning: http://forum.slowtwitch.com/...;;page=unread#unread

And it really does not apply to triathlons unless you are a drafter.
Not really... the link it talks about weight vs aero. i firmly believe it's all about the aero (unless you are doing a straight up 10% grade one way TT climb)- as you can build up bikes to be very light and very aero (they don't have to be mutually exclusive). i'm looking for quantifying of the aero aspect- specifically to frames. also- the frames S2 or even more aero S3 (per Cervelo's website) could indeed be more aero than many poorly designed TT rigs out there- as there are many design elements that seem to be used in the S2/S3/P3/P4- especially on the front end/downtub/top tube. But I'd like anyone that ever has seen, heard, any data to chime in and also pick apart anything that needs to be picked apart.
Last edited by: mlinenb: Feb 27, 09 20:35
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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I think it must total percent reduction for a "typical" CdA, which would mean the difference between frames would have to much more significant (it's late, so that could be faulty math). 1.5% of the total drag is more in line with what I've seen for the Soloist. I think the difference would be more *without* bottle cages on, so that might be something to factor in. A bare r3 might do worse compared to a bare s2 than both frames with two bottle cages on. But that's just guesstimation.

But yes, as he says "OVERALL drag," which must mean total CdA. The weird thing about that it is that it makes assumptions of positional CdA.

Another interesting thing to note is, from your chart of "aero" frames (I've heard the soloist actually trumps a lot of the pseudo-aero frames on that list), is that it is certainly possible for a frame like the Oro to have WORSE drag than a frame like the R3. If the tubes are poorly designed, I can see that it is entirely possible that they would have more frontal area - especially at higher yaws, meaning they could indeed be slow.

If you look at a lot of the very old steel frames from the early days of Ironman, those tubes had TINY ODs. I bet you those frames were a fair bit faster than frames built with ultra-fat carbon tubes that had no mind paid to aerodynamics.

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [roady] [ In reply to ]
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In Reply To:
I certainly could be wrong, but when he says, it seems pretty clear that he means 'overall drag', including the rider. Obviously, the smaller the rider, the bigger the percentage. As I said on that thread, the difference is pretty small (and when you factor in sitting in a pack, where wind resistance is reduced 30-40%, that 4-5 watts becomes 1-2 watts).

Still, it all adds up--and most often the most critical moments in a race are whey you're getting the least draft.

As far as your other question, I suspect 2 things: the Cervelo road bike isn't nearly as aero as a P2/P3, and a round tubed bike is better than the worst TT frames (and almost all giant-tubed road frames).
10 points. And to clarify, for us the "average" size rider is our test dummy.


Gerard Vroomen
3T.bike
OPEN cycle
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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Tom A. found the P2k to be 2sec/km slower than the P3C,and also finds the soloist/s1 to be aerodynamically near identical to the P2k

using the ROT.....

the soloist/S1 has 0.4lb more drag than P3C

~=(180+690)g drag
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Re: 1.5% savings from Cervelo means?.. Zinn- lightweight vs Aero [mlinenb] [ In reply to ]
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