I don't know if you have ever done a bike race, I've done a couple hundred and every single one of them has moments where riding in the pack is hard. Lots of such moments. The reason it is hard in those moments is because of air.

---

---

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

And yet, there are wind tunnel tests that show your buddy apparently did something wrong in his modeling:



You said "frame/fork that is less than 1kg", which means together...I highly doubt that together the frame and fork weigh less than 1 kg.

---

http://bikeblather.blogspot.com/

You're right, for the same amount of effort on a flat section, it's the same aero drag whether I'm drafting or not. My speed will just be different.

Going with this, how does pack riding change the proportion of what each component contributes to the aero drag? I'd almost think that pack riding would make an aero bike give you more savings since your body is better shielded by other riders than your frame is shielded by other frames.

I think his buddy probably tried toe explain to him how they were able to use CFD to make the addict as aero as the foil while using more normal looking tubes, perhaps tubes with better stiffness/comfort/weight properties.

He has then taken this to believe that his roundish tube bike is faster than an S5/propel or something =)

---

---

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

CFD is only as good as the model design and parameters used, and of course the operator.

GIGO still applies, even to software used by a PhD.

Hey guys...

OK...frame and fork weight on the Scott Addict team issue in my size...claimed 790/300...so yes, over the 1kg mark. And I checked my actual frame and fork that we weighed before assembling the bike...it was 1060g...but included the mounting brackets for the drive train and the headset parts were installed...so we are arguing about grams for this or that side of the 1kg mark....my point was simply that I do agree aero is more important than weight...even though I bought a light frame...and my total bike weight comes in at about 6.5kg with only very average wheels in terms of weight. (Fulcrum Racing 3...it's my training bike after all!)

As for the aero data.....I thank you for publishing the chart as I can use this next time against him! I want to be clear, however, he was not comparing the addict tube profile to the foil's. He was comparing Foil's truncated cam to a traditional round tube and arguing the round tube was actually more efficient than the Foil profile. I too found this unbelievable and still do fully trust it. What I am saying, however, is there are numerous ways to generate data about the aerodynamic performance of a bike and that creates all kinds of room for marketing spin. For example, some frames perform better than another frame at a certain yaw angle, but worse at others. In these cases, the answer to which frame is more aero is...it depends on the yaw angle. So there is no black and white...and that's where even honest differences in the science can lead to marketing hyperbole instead of honest insight into the performance of a frame.

Here is a short youtube video that shows the CDF findings; you can see from the shapes which tube profile belongs to which aero design and the truncated designs create far more turbulent air than the full profile tubes they are modelled on. I'm putting this out there for conversation and interesting debate...not to prove I'm right or someone's wrong. I just ride bikes fast...not design fast bikes....and when it comes to riding fast...the rider still makes more of a difference than the frame!


"//http://www.youtube.com/...xi7t5lSBgS7i3vGS1BgQ"

Then why is everyone so obsessed with saving a few grams here and there on their bike? Serious question.

Because eating is fun and people aren't good at physics?
Or they live around mountains.

---

---

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

Welcome to slowtwitch Darren.

Not everyone here is new to this and is just assuming certain marketing claims are true.

Some people here have been to the wind tunnel themselves, or done their own field testing using clever methods like the Chung Method. Tom A has done both. Others like Andy F have invented amazing tools like the Alphamantis Track Aero system that Trek used to help Jens break the hour record.

There is quite a wealth of experience here, please do enjoy it!

---

---

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

Thanks Jack!

I don't usually post so much but have a technical background, passion for tri, and the pleasure of knowing bike engineers and designers. I find they muddy the waters about as much as the marketing types!

I wish I could identify the quantitative factors behind my strong and clear preference for my addict over my foi . Both are made of the same carbon in the same Giant factory in Taichung. But the addict speaks to me in ways on climbs that my foil never could and makes my p5 seem a Jon not a pleasure. (But a fast job!) .And I suppose its those individual preferences that will keep the bike market diverse and strong.

I watched it.

I don't see a foil shape that matches the bike.

Shape matters a lot.

Anything to back up this Jack?

---

http://cds-0.blogspot.com

I remember digging around on this a lot, found a couple people who had done tests with power meters at the hub and crank and found no discernable difference. Also found a post where Damon Rinard said they had tested the flexiest frame they could find and got the same results. Resulting conclusion was that if there was a difference it was within the error of the powermeters.

There is a question (for me) of whether the flexiest and the stiffest frameset out there will affect how much power you can generate, and if it will affect handling. Also worth noting that at this point in time frames are so stiff that a 15% increase in stiffness is the difference between 4mm and 3.6mm of deflection. The result is still super stiff.

(Upfront notice here, team is sponsored by Scott) As for the debate about foil/addict. They do come into shops at sub 1kg in the right sizes. I saw a 54cm frame, painted come into the shop weighing that it is impressive, I'm sure larger sizes and individual frames differ but it's still pretty incredible. The tubes do have really nice subtle shaping 2/3 of a foil in terms of aero.

---

---------------------
Jordan Oroshiba --- Roadie invading Triathlete space for knowledge access

I think the stiffness can easily affect the handling.

Last thing I have heard is that Dimond was trying to quantify the differences in rolling resistance between its beam bike and double diamond ones. Let's see what they come up with because, as you point out, anything involving powermeters won't give valid answers.

---

http://cds-0.blogspot.com

They're going to have a hard time doing that since it's dominated by the tires (if running proper pressures) on a "compliant" bike or not.

---

http://bikeblather.blogspot.com/

My problem is with how most of these measures of "stiffness" are performed, i.e. with unrealistic boundary conditions and loading...the only one that comes close is the Cervelo test.

---

http://bikeblather.blogspot.com/

Only that people have tried to measure it with two power meters and haven't.

and that I haven't seen a discontinuity in my own power when switching to more or less stiff bikes with my powertap.

---

---

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

Foil "D" is the Scott Foil profile. Just can't say that for brand reasons so I'm just suggesting this.

AND...this is not a knock in any way on Scott bikes. LOVED both my foils and SUPER MAN CRUSH love for my addict! Great bikes and Scott service in Taiwan is above reproach!

Really? OK, well I agree it's a pretty sucky looking aero shape if that's the case.

Perhaps the tube not being vertical changes things when actually in use.

I agree completely with you Watt Matters.

I sent the video and the claim to Scott, but they never responded.

The research was conducted by a Taiwan-based independent frame design-retail company (outsources manufacturing, but design is legitimately completely unique to them..not a sticker brand) in partnership with Taiwan's National Center for High Performance Computing which gives them access to very precise CFD data that goes well beyond the resolution of most CFD software. That does not make it correct, however. Simon Smart, who worked on the Foil, has an incredible and deserved reputation in aerodynamics.

So....even at the level of data presented in this thread...the chart posted earlier and this CFD video...aero is still a he said she said consumer gamble as I have no ability to verify which claim is correct. So that to me significantly dilutes the importance of buying an aero road bike.

And when it comes to tri bikes...80% of aero is all about fit fit fit...and the bike's aero qualities are gravy...and yes...at the pro level....that could be the deciding factor....but for the rest of us, if I have a great fit, I can still take minutes off my 2:23 HIM bike split through more hard work....it's probably a little more challenging for Kienle to shave off an additional 10 minutes through training alone!

i've always enjoyed your posting but lately you've been on fire.
cheers.

Well I would place a lot more value in independent tunnel or field testing of a whole bike or frame using good protocol over a CFD model of a 2-D cross section of one tube.

Don't present false trichotomies.

One can work on optimising position, equipment choices and fitness at the same time. These are not mutually exclusive.

Sure at various points in an athlete's development journey some areas may result in greater gains than others, but that does not mean they should ignore all legitimate ways of improving performance. The only reason I can see for not doing so is one of resource (time, money) constraint or performance doesn't matter much to you (e.g. you're a participant, not a competitor).

This thread is great. Some of you guys should head on over to timetriallingforum in the UK where most folks have simply accepted this science and are now getting on happily with their lives, trying to be as aero as possible and not worrying too much about weight. It makes for a really interesting contrast with the endless aero vs weight debates on ST. They have even accepted clinchers into their lives.

and those guys are fast as shit despite living in a place where it is too cold to train!

---

---

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