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PostPosted: Tue Nov 14, 2017 1:26 am 
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Joined: Mon Aug 29, 2016 11:19 am
Posts: 406
Hi WW's

I've been wondering what makes an aero frame aero. (I know changing the frame only saves you like 17 watts, but setting this aside)

I've watched some Hambini videos talking about NACA tube profiles and analyzing some frame properties. What is good and what is bad and so on...

What strikes me as unusual is that I don't see the main common aero features on the madone frame and yet it still tests very good in the wind tunnel in several tests. (The first test I read I thought "ok good one trek marketing, you're not fooling anybody)

1. I'm looking at the down tube, and I see a huge surface there like a sail from the truncated tube profile.

2. The seat tube does not come close at all to the rear wheel.

3. Tubes all around the bike are not exceptionaly narrow and they are all quite severely truncated.

4. Front wheel does not go into the down tube a little. The head tube and upper down tube area is not particularly drop shaped in the horisontal plane

Can it be true that the gains that put the madone on top simply come from places I hear people say are negligible?

1. Exposed cables

2. Aero brake calipers

3. Integrated handlebars


In the same wind tunnel tests a frame that to me looks to be more like a TT/Tri bike gets worse results.

Should I just give up my own convictions of what makes a good aero frame and just buy a madone or is something fishy going on here? Is it all magic and we just have to wait for the results before we know if it's aero or not?

Thank you for reading.

/a


Last edited by alcatraz on Tue Nov 14, 2017 2:49 am, edited 1 time in total.

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Posted: Tue Nov 14, 2017 1:26 am 


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PostPosted: Tue Nov 14, 2017 1:46 am 
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Joined: Thu Mar 28, 2013 4:42 pm
Posts: 861
Location: Pa USA
Kamm profiles. Ugly ish but work. Look at frontal profile of the bike as well.


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PostPosted: Tue Nov 14, 2017 2:35 am 
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Joined: Wed Mar 15, 2017 5:30 pm
Posts: 312
This is a shot in the dark but maybe it just works really well as a system. The individual tubes and parts are aero if not the most by themselves but possibly they work together better than on other bikes.


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PostPosted: Tue Nov 14, 2017 3:10 am 
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Joined: Sat Jan 15, 2011 1:24 am
Posts: 63
The Pinarello F8 and F10 are just as aero as the Madone according to Germany’s Tour Magazine. Obviously the truncated aero foil works even though Hambini dismisses it with his computer modelling. Thing is that the Pina has exposed cables so they must not be such a big deal as the Madone and Pina are basically the same and the Pina has normal bars too.

I have an F8 and an S5 and they both feel fast to me. Faster then my old R5


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PostPosted: Tue Nov 14, 2017 3:13 am 
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Joined: Fri Sep 15, 2006 6:02 am
Posts: 3762
Location: On the bike
Tube shapes + integration.

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PostPosted: Tue Nov 14, 2017 1:41 pm 
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Joined: Mon Aug 29, 2016 11:19 am
Posts: 406
What would the ideal aero bike be in your opinion?

An S5 built with kammtail tube shapes?

A trek speed concept is more like a cervelo than a madone. Weird?

Also was the kammtail tube shape introduced first in the madone 9 and speed concept 9?

/a


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PostPosted: Tue Nov 14, 2017 2:11 pm 
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Joined: Sat Oct 23, 2010 9:36 am
Posts: 550
Location: Where the permanent autumn is
If superfast (+ super comfortable and light) aero bikes would be so easy to build based on just "an opinion", Berk would be creating one for me right now :D :D

More or less, "peak aero" has been reached and you won't see additional gains of more than a couple of watts versus the current cream of aero offerings. Better (easier) integration, better comfort within the current aero envelope, but more aero - hardly.

That's at least one reason more why industry is doing so big push on disc brakes, otherwise almost any current top end bike in aero or light category is a bloody great machine, thus, greatly diminishing any incentive to upgrade it each year or two.


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PostPosted: Tue Nov 14, 2017 4:00 pm 
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Joined: Wed Aug 14, 2013 9:53 pm
Posts: 109
alcatraz wrote:
Hi WW's

I've been wondering what makes an aero frame aero. (I know changing the frame only saves you like 17 watts, but setting this aside)

I've watched some Hambini videos talking about NACA tube profiles and analyzing some frame properties. What is good and what is bad and so on...

What strikes me as unusual is that I don't see the main common aero features on the madone frame and yet it still tests very good in the wind tunnel in several tests. (The first test I read I thought "ok good one trek marketing, you're not fooling anybody)

1. I'm looking at the down tube, and I see a huge surface there like a sail from the truncated tube profile.

2. The seat tube does not come close at all to the rear wheel.

3. Tubes all around the bike are not exceptionaly narrow and they are all quite severely truncated.

4. Front wheel does not go into the down tube a little. The head tube and upper down tube area is not particularly drop shaped in the horisontal plane

Can it be true that the gains that put the madone on top simply come from places I hear people say are negligible?

1. Exposed cables

2. Aero brake calipers

3. Integrated handlebars


In the same wind tunnel tests a frame that to me looks to be more like a TT/Tri bike gets worse results.

Should I just give up my own convictions of what makes a good aero frame and just buy a madone or is something fishy going on here? Is it all magic and we just have to wait for the results before we know if it's aero or not?

Thank you for reading.

/a


Here is the hard thing about aerodynamics....it's hard and unpredictable. The best tool we have as consumers to understand the aero properties is third party tests....but even those are pretty fallible.


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PostPosted: Tue Nov 14, 2017 4:19 pm 
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Joined: Wed Jan 12, 2005 6:04 am
Posts: 606
Location: USA
After riding both a Felt F1 and a Pinarello F10 extensively, there is no question in my mind the F10 is far more aero.

The Madone in contrast always felt too flexy, and certainly does not lend itself to sprinting like the F10 does.


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PostPosted: Tue Nov 14, 2017 5:52 pm 
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Joined: Tue May 23, 2006 9:39 pm
Posts: 1064
alcatraz wrote:
What would the ideal aero bike be in your opinion?

An S5 built with kammtail tube shapes?

A trek speed concept is more like a cervelo than a madone. Weird?

Also was the kammtail tube shape introduced first in the madone 9 and speed concept 9?

/a



Kammtail has been around for awhile. i have Kammtail shaped tubes on my Parlee ESX...and that's not a new bike either. some frame sets have Kammtail seat tubes and downtimes. can't remember which ones.

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PostPosted: Tue Nov 14, 2017 8:03 pm 
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Joined: Mon Jul 24, 2017 12:02 pm
Posts: 514
Kamm shaped tubes aren't optimal... They're used because the 3:1 rule was in place and because they're practical for sections like the downtube where a bottle would be placed.


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PostPosted: Tue Nov 14, 2017 8:34 pm 
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Joined: Sat Dec 11, 2004 1:31 pm
Posts: 1790
Location: Funky Town, NJ
I've been enjoying my project one H1 since August. My first aero bike... it definitely feels quick.

Also note the thing is super comfortable and stops well.

I think you've got only part of it.

1. Exposed cables
2. Aero brake calipers
3. Integrated handlebars

I'll add, frontal area: head tube, bar/stem interface, and seat mast

Also seat stays and top tube junction.

Air flows as smooth through the rider as possible.


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PostPosted: Tue Nov 14, 2017 8:37 pm 
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Joined: Thu Mar 08, 2012 11:43 pm
Posts: 3332
alcatraz wrote:
I've watched some Hambini videos talking about NACA tube profiles and analyzing some frame properties. What is good and what is bad and so on...

Cervelo put out a white paper way, way, waaaaay back in the days of either the Soloist SLC or original S3 explaining why NACA profiles didn't work very well as part of a complete bike system, and why they'd started developing their own aero tube shapes for each individual part of the bike frame instead.

Why would you expect a frame that used NACA profiles to be competitively fast? :wink:


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PostPosted: Tue Nov 14, 2017 8:40 pm 
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Joined: Sun Jun 18, 2006 10:29 am
Posts: 6678
Location: Athens, Greece
Actually Madone is considered as 'the aero king' because some tests say so. Keep in mind, though, that these tests do not follow strict scientific protocols and their results are not actually processed.
In general tests done by manufacturers or cycling magazines are neither rigorous nor independent. Actually the only PhD research on bike aerodynamics ever discussed in this forum has as its main conclusions that the aerodynamics of the frame itself (comparing track frames) do not, practically, matter:

https://ir.canterbury.ac.nz/bitstream/h ... lltext.pdf

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Posted: Tue Nov 14, 2017 8:40 pm 


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PostPosted: Tue Nov 14, 2017 10:23 pm 
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Joined: Wed Sep 20, 2006 1:03 am
Posts: 507
Location: Madison, WI USA
Respectfully, KGT, that dissertation's conclusions do not say what you suggest. In fact, the author says quite the opposite on page 234:

Lindsey Underwood wrote:
A relatively large impact on drag was also found by changing either the frame (2.8%) or the wheels (2.5%) individually.


She essentially writes that since the rider is responsible for most of the net drag, she concentrated most of her efforts in drag reduction on the rider.

Underwood reaches this conclusion after sticking some quasi-random foam shapes to already-aero pursuit bikes with electrical tape. One of the pieces of foam gets taped to the steerer clamp of a conventional stem and resembles nothing so much as a half-finished Chipotle burrito (Fig 7.1a, p. 148). This is not to impugn Dr. Underwood's work, but rather to highlight that she didn't make a serious attempt to say whether the aerodynamics of the frame "matter in practical terms." (I'm paraphrasing you here).

Underwood compared two fairly aero 2008-era pursuit frames and made small, slightly goofy modifications to them. The conclusion she reached about frames is that (a) aero frames are already aero, and (b) even two aero frames can have significant differences in drag between them.



Edit: typo-fixing


Last edited by youngs_modulus on Wed Nov 15, 2017 12:15 am, edited 1 time in total.

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