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...
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...