Save your cash, and lose 5lbs of body weight... or 10lbs... or 15lbs...

Hi bootsie,

I have not yet ridden an S5, but the lab numbers point to very similar ride feel as the new S3. Quite a bit stiffer torsionally, and handles very very well.

Cheers,

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

That's all else being equal though. If you chose bad lines, the aero bike won't save you.

But even if you lack good navigation, the testicular fortitude and bike handling skills to brave that speed and control the bike...you'll still go faster on the flats or climbing.

There are other factors besides aero and weight. Fit and Stiffness are also pretty important. Going from a flexy bike to a stiff bike was a big change in watts; maybe 10-15?

People talk about aero frames all day but in races and hammerfests 95% of the pack is riding on the hoods with an almost horizontal back. Because my bike fits and I ride in the drops with bent elbows I'll take my low profile vertical back over an aero bike any day of the week. Could I have both? Possibly but I would have to sacrifice riding a bike that didn't quite fit they way I like. I may get used to it but after riding a bike that did fit for two years I'm a stickler about it down to the centimeter.

Why don't you fit all aero frames? If you found an aero bike that fit like your current frame guess what, you would be faster.

I went from a Cannondale SuperSix (non-evo) to a Giant Propel. Both bike feel incredibly stiff (and very nice), but the Propel is faster on descents to a surprisingly degree. Once I got used to the extra push from cross winds, I haven't seen a single disadvantage of my aero road bike (though I race crits more often than road races).

Can you point to any testing confirming stiffness results in more power at the wheel and therefore more speed?

Lots of aero testing confirms the benefits, never seen the same for stiffness.

I recently switched my road riding from a 10 year old Kestrel Talon (aero, ~17.5 lbs) to a Domane Classics with all the bells and whistles (non-aero, 15.5 lbs). When I got done fitting my Domane, I ended up with the exact same 10 cm saddle-to-bar drop and reach I had on my Talon (Talon put me over the front wheel more though). Comparing files from solo training rides, I definitely got more mph per watt on the Talon, but for some reason my ftp is 10-15 watts greater on the Domane. It's a different power meter, so that could be part of it, or maybe it's just the fit, or maybe I'm just getting stronger at the end of the season.

The Domane is definitely more comfortable (duh), and if a race featured lots of pack riding and rough roads, I think the comfort/sprint stiffness would win out. I have to say though, it is a little amazing how well the 10 year old cheap azz Talon has held up against modern offerings-- an aero road bike before it's time!

It is an interesting discussion...and with so much "kamm-tail" techno-marketing jargon...it's hard to tell fact from fiction.

I had two Scott Foil Aero Road bikes...a Foil 20 (pretty flexible bike in all the wrong ways) and a much much better Foil Team Issue. Both Foils fell victim to car crashes that were not my fault. So...having invested in a P5 for triathlon, I decided to give the Scott Addict Team Issue a try instead of the Foil.

The Addict feels a lot better and my Strava KOM segments are getting faster, but I think that's more the rider than the bike. But...on the rare flats when I ride the Addict I can "feel" it sucking energy! (Same geometry and exact same fit between Foil and Addict)

BUT....a friend of mine in the industry showed me his CFD simulations that highly suggest the Foil tube profile is WORSE than round tubes....and the Addict is essentially thin round tubes. But...until there is a more standard way of analyzing aero bikes...as consumers we are shooting in the dark. Though I highly respect Cervelo's reputation for aero-prowess....and given my P5...I would certainly be looking that way again if/when I need another road bike.

Also....can anyone comment on weight? Yes, I ride a frame/fork that is less than 1kg...but I didn't buy it because of its mass. My question is this....is 1kg on the frame similar to 1kg on the rider in terms of its impact? I assume it is. And in case of the argument, but the rider can always lose that kg and the bike is the bike so it's better if it is lighter...my BMI is 19 and body fat is 5.8% and if I still want to swim fast....I need all the KGs I have now!

Nope. Any sort of modern aero bike will not be losing more than a single watt to frame flex.

0 watts

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

yes, and is the same as 1kg of wheels (to very very close approximation)

and if it isn't mountainous, that 1kg will have very little impact.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

This is only true if losing 1kg of rider does not have a negative impact on rider power output. In reality, most people lose a little power when they lose weight. I know it is very minor, but the assumption that you can just lob off a chunk of fat with no impact on the rest of your body is an oversimplification, especially as a rider approaches the lower limits of leanness.

I don't think that is usually the case in reality.
I think most people lose some power while at a calorie deficit and then give up.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

"inconsequential", sure. Zero watts? I doubt it. The business of a frame being a spring always gets trotted out--but before you bring it up as well, do you really believe that *all* of the power lost due to flex is returned in a way that provides forward propulsion? That seems unreasonable. I'm willing to bet that the differences are within the measurement error of power meters; otherwise, you could reliably test this by concurrently using a crank based meter and hub based meter. No one has demonstrated this yet (that's I've seen), so I'm guessing the difference is less than 2%. But it doesn't mean that it doesn't exist. I don't think 10-15 watts (1%) at peak power is actually that unreasonable, but that's a total guess.

Hell, I could even see that frame flex could impact Crr in extreme circumstances (like standing and sprinting or climbing). Doesn't mean I won't ride an aero bike, as what ever differences that exists are certainly overshadowed by aerodynamics, but I wouldn't completely ignore the possibility that frame stiffness may impact efficiency.

That, I could see as being a much more plausible thing, and it would be fascinating to investigate it.

People have put crank and hub power meters on bikes to try and measure power loss due to frame flex and can't find it.

Which suggests the difference is sub 2 watts during an all out sprint at worst.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

I'm not sure that's what it means. I've never seen .2% agreement between power meters, and I've spent a lot of time using an SRM and PT at the same time. I think it just means the difference is 1% or less.

You would expect the delta to change as a function of torque, or power though.

I suppose ultimately if you wanted to get at the ultimate answer - "what is faster" you take an S5 and an R5 and do many sprint repeats and plots the speed/power relationships.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Your friend might want to work on his CFD skills...


There ARE standard ways of evaluating them: wind tunnels and field testing with power meters.


No you don't ;-)

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http://bikeblather.blogspot.com/

I may be misinterpreting this, but are you saying losing 1 lb of body weight is the same as losing 1 lb of bike weight?

Well, technically the top of the line Addict SL is marketed as sub 1kg for the frame and fork, but I haven't seen any independent claims confirming this. Seeing as this guy's Foil 20 is 80g over claimed, I doubt that the SL is sub 1kg.

If I was doing a solo TT effort, I would pick the aero road bike unless it's ridiculously steep. If I was drafting off of a semi (no air flowing over me or my bike) the entire race, I'd pick the lightest bike possible if there was any climbing involved. On the spectrum of solo TT effort to drafting off of a semi, where does sitting in the middle of the pack sit? If I were to gain 15W in a solo effort with an aero road bike over a non-aero one, how much would I expect to gain if I sit in the pack the whole time?

You still gain an advantage even sitting in a pack on an aero frame road bike.

Yes people with PhD's in engineering are all dumb which extends to standard CFD software that has been verified in wind tunnels too. Clearly they are clueless! Having seen the data myself there are many reasons many aero bikes are not aero. It is one of the advantages of living in Taiwan where people design and build bikes instead of just marketing them and putting on pretty stickers!

As for a Scott addict size 54 frame and for not weighing less than a kg...I have no idea why you dispute that... I've weighed my own frame and the data from Scott all indicate this. Seems simple enough!

as far as how fast you ride your bike, yes.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

The scott addict is about as aero as the foil because the addict was subtly shaped to be aero as well, the tubes aren't round.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter