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PostPosted: Tue Nov 14, 2017 11:20 pm 
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Posts: 278
alcatraz wrote:
2. Aero brake calipers

3. Integrated handlebars
/a

I've read that those two have huge influence on how aero the bike is.
-aero shaped handle bar worth roughly as much as entire mid center to the back of the aero frame in drag reduction. Aero shaped handle bar, always.

-Fork crown area, top of front wheel and brake is hot area. Giant claim that clear those area up using disc brake instead of front rim brake make up for aero penalty using disc brake instead (on Propel Disc launch). Orbea make fork wider to reduce turbulence and claim to save noticeable watts.
Madone's integrated rim brake with all hidden cable are good. The next best thing is Tririg Omega X. I installed one Tririg for my friend's Shiv. It's surprisingly strong despite their look and how they function. However, it feel strange to try to modulate when you are not used to it due to their highly non-linear spring mechanism. The Tririg aero tested very well.


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PostPosted: Wed Nov 15, 2017 12:14 am 
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Location: Madison, WI USA
To answer the OP's question, I can't put it much more succinctly than morganb did.
morganb wrote:
This is a shot in the dark but maybe it just works really well as a system.

As others have pointed out, you can't just add a checklist of aero features to a frame and expect to end up with a class-leading aero frame. These features are interdependent...you can't isolate them.

There's a good example of this in the car world. The Nissan Leaf and the Toyota Prius both have bulbous headlights, and it's not a coincidence. It's to route flow around the side mirrors, which are a major source of drag and wind noise:

Image
Side mirrors are draggy. Bulbous headlights are draggy. But bulbous headlights in exactly the right place bring net drag down substantially.

The Madone is (a) designed as a system and (b) takes advantage of lots of small optimizations like minimizing exposed cables. To KGT's point, many bikes are in the same league, and we don't have a large body of rigorous tests that all show the Madone having much lower drag than its peers. We do have a number of reasonable tests put it solidly among the top bikes--and often at the top. They all use different methodologies, wind speeds and differently-weighted angles of attack. The fact that they tend to converge on similar answers suggests that the Madone and Cervelo's S5 are two of the fastest bikes on the market.

Hey, look! We just performed a meta-analysis. Science, bitches! ;)

Regarding the diverging Cervelo and Trek approaches: 20 years ago, aero wheels were as narrow as possible and had sharp-tailed airfoils. Now, the fastest spoked wheels are broad and blunt. But the fastest of the old-style pointy wheels (like the Specialized/Hed Trispoke) are still pretty good*. And the very fastest (disc wheels) are still the fastest today. It's clearly possible to make a fast bike with either approach.

Trek's Kamm-tail shapes are more aero than I expected when I first saw them, and they're unquestionably more structurally efficient than narrow, NACA airfoil-like shapes Cervelo used on its first-generation S3. One reason some people consider the Madone "the aero king" as you put it" is that it's a first-tier aero frame that demands no compromises on either torsional stiffness or especially on comfort (due to the IsoSpeed decoupler).

One thing to remember is that we (as consumers) don't care which bike is fastest because none of the top aero bikes is the fastest. The fastest bike depends on which day it is and what the conditions are on that day. Most of us can only afford one high-end aero bike (if that). So we will pick one of the fastest bikes, and it will be the fastest on some days. We just hope that the one we choose will be fastest on most days. It's a gamble.

I've said this before, but I'm putting my money on the Madone to be fastest on most of the days I race. I'm waiting for disc brakes and any changes Trek will make since the UCI dropped its 3:1 aspect ratio rule. But even though I work in a related field, there is no One True Aero Bike for me. Like a number of other posters here, I understand everything manufacturers say in their white papers. I agree with some claims/experiments and disagree with others, and I've even done a few little CFD studies for myself to figure out what might really matter. But when I hand my credit card to the LBS, I'm gambling too. There is no definitive study and there is no clear right answer here.



-------------
* I think it's fascinating that the Trispoke didn't use a NACA airfoil cross-section. NACA airfoils don't show up much on fast modern wheels, either.


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Posted: Wed Nov 15, 2017 12:14 am 


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PostPosted: Wed Nov 15, 2017 12:40 am 
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Location: Madison, WI USA
Bridgeman wrote:
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.


If you prefer the Pinarello F10 to the Felt F1, you should buy the Pinarello. But human beings can't feel the difference in drag between two aero road frames, even if ridden back-to-back...our gluteal dynamometers aren't nearly precise enough.

Even a good power meter on its own is not good enough...it's easy to trick yourself and not only find the slower frame faster, but even find a negative coefficient of drag. Robert Chung's "virtual elevation" method (AKA the Chung Method) addresses these pitfalls. Seriously, it's worth a read:

http://anonymous.coward.free.fr/wattage ... ct-cda.pdf

I'm not second-guessing your impression that the Pinarello seemed faster than the Felt; it might even be faster. But if it is, none of us could tell just by riding it. The differences are too small.


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PostPosted: Wed Nov 15, 2017 1:37 am 
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Location: USA
The differences are small, but cumulative. Over the course of a long ride I repeatedly notice the difference in that I'm fresher towards the end. Also, the aero aspect reveals itself at high speeds.

Apart from the aero aspect is the efficiency element, which also contributes. Due to the different frame materials and shapes the Felt F1 is more lossy. The F1 is a 2014 version, does not utilize the latest Textreme weave and is not an aero shaped frame. I'm certain the difference would be obvious when viewing force vs deflection plots of the bottom bracket/crankset. Given, the bb area is not the only contributor to efficiency, but it is one of the weaker areas compared to the Pina F10.

Differentiating the two, (aero/efficeincy) would be the task to undertake.

Thanks for the Robert Chung reference. Always like to revisit!


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PostPosted: Wed Nov 15, 2017 2:30 am 
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Location: Madison, WI USA
Well, strictly speaking, the BB has nothing to do with efficiency...there are no detectable efficiency differences to those two frames due to stiffness (force/deflection). That's not to say there's no difference in stiffness or feel. But if the F1 is measurably more lossy than the F10 due to materials and shapes, please PM me, as we have a physics paper to write that might just make it into Science or Nature.

I'm not trying to be flippant. It is worth remembering, however, Richard Feynman's admonition that "the first principle is that you must not fool yourself--and you are the easiest person to fool."

Regarding losses, it's not hard to differentiate between what's lost to flex and what's lost to drag: it's all aero drag. I admit I was visualizing the Felt AR (their aero road bike) not the F1...there is certainly a measurable drag difference between the F1 and the F10, but again, it's not one you can feel. Human beings are terrible data acquisition devices. I certainly am.

In a thread asking why one bike is faster than some others, this seemed worth pointing out. But naturally, none of this invalidates your preference for the Pinarello, and it's certainly more aero than the F1, just as you suggest.


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PostPosted: Wed Nov 15, 2017 3:49 am 
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youngs_modulus wrote:

(...)
The fastest bike depends on which day it is and what the conditions are on that day. Most of us can only afford one high-end aero bike (if that). So we will pick one of the fastest bikes, and it will be the fastest on some days. We just hope that the one we choose will be fastest on most days.
(...)


Could you elaborate on that?
Do you mean it depends on the wind angle and wind velocity?


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PostPosted: Wed Nov 15, 2017 6:26 am 
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Posts: 278
youngs_modulus wrote:
Regarding losses, it's not hard to differentiate between what's lost to flex and what's lost to drag: it's all aero drag. I admit I was visualizing the Felt AR (their aero road bike) not the F1...there is certainly a measurable drag difference between the F1 and the F10, but again, it's not one you can feel. Human beings are terrible data acquisition devices. I certainly am.

also suspension loss, some frame make me feel fresher because it's more compliance over rough roads. Those Vibration also kill speed, so that could be the thing separate between two frames.
PS. with 25c or bigger and 80psi pressure or lower, frame harshness wouldn't matter much but it might be big deal on 110psi 23c.


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PostPosted: Wed Nov 15, 2017 7:51 am 
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Location: Madison, WI USA
TonyM wrote:
youngs_modulus wrote:

(...)
The fastest bike depends on which day it is and what the conditions are on that day. Most of us can only afford one high-end aero bike (if that). So we will pick one of the fastest bikes, and it will be the fastest on some days. We just hope that the one we choose will be fastest on most days.
(...)

Could you elaborate on that?
Do you mean it depends on the wind angle and wind velocity?


Sure, but before we talk about airspeed velocity, we need to decide whether the swallow is African or European.

Sorry. I couldn't resist. ;)

Anyway, yes. Going from memory, the Madone does best under relatively high yaw angles because it stalls later than a NACA airfoil. So if Mark Cavendish cheekily tries to close the gate on me in a crosswind, I probably want the Madone. If Marcel Kittel is bearing down on me into a headwind, I may do better on a Cervelo S5.

The question is: which is more likely? (Hint: none of the above, at least for me). One comforting thing to keep in mind is that as long as you're riding an aero frame with aero wheels, choosing different aero gear only matters if you lost by about a tire width. If you lost by more than that, the gear wasn't the problem.

There's no one aero road bike that's fastest in all situations. Honestly, you're doing well if you choose a bike that's fastest in a plurality of situations. Those situations involve wind speed, direction, whether you have a lead-out, etc.

Does that answer your question?


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PostPosted: Wed Nov 15, 2017 8:08 am 
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Thanks!!


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PostPosted: Wed Nov 15, 2017 8:19 am 
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I'd say an aero bike is obviously a bike with aerodynamic tube sections and that will keep cables and accessoires shielded from influencing the streamline. But besides that, it's also about how the bike forces the rider to be more aerodynamic. Many aero bikes will have a longer wheelbase and lower stack, to aid with an aerodynamic position of your body. This makes them a bit more strenuous to ride for your back, but it makes the whole package of you and the bike more aero and it helps with high speed stability, which an aero bike is more likely to reach than say a climbing or endurance model.

Making yourself more aero is more important for performance and cheaper than buying an aero frame. Angle your saddle a bit more forward, get yourself some handlebars that are 2-4 cm more narrow than you are used to, get a slightly longer stem and remove one or two spacers, and you're well on your way.


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PostPosted: Wed Nov 15, 2017 11:43 am 
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Location: Athens, Greece
youngs_modulus wrote:
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.


I am afraid that you misunderstood what you read:

"A relatively large impact on drag was also found by changing either the frame (2.8%) or the wheels (2.5%) individually. A change in the frame includes a change in the type of handlebars used, which in turn affects the position of the forearms and hands, and alters the frontal area and direction of the flow over the rest of the body." p. 234

while

"A change to the shape of the bike frame had no significant impact on the drag (<0.3%)" p. 234 a few lines above

So what she says is that the shape of the frame itself does not matter. It matters only when the frame alters the rider's position.

Anyway it seems that you have done more rigorous research than Dr Underwood. Can you please share it with us? I honestly respect your knowledge and I would like to learn more.

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PostPosted: Wed Nov 15, 2017 3:50 pm 
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"A change in skinsuit had a significantly greater impact on the aerodynamic drag compared to all other changes made to the equipment, and a change to the shape of the bike frame had no significant impact on the drag(<0.3%). This low change in drag for the bike frame is likely to be due to the fact that all bikes used in this study were already optimised in terms of aerodynamics with an aerodynamic frame; a comparison between a non-aerodynamic and aerodynamic frame would likely lead to a greater change in drag." (234, Underwood)

Did you not read the line right after what you quoted?

Either that or you chose to ignore those important sentences to intentionally twist the words out of its context.


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PostPosted: Wed Nov 15, 2017 5:00 pm 
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Of course I did. BTW did you read this thread?
This thread is about aero frames and wonders if or why Madone is the best. No? So this PhD research proves that among similar frames (aero track frames) the shape of the frame itself does not matter or it is by far the last thing that matters. Is it clear?

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PostPosted: Wed Nov 15, 2017 5:29 pm 
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Yes I read this thread, and no, it's not clear.

kgt wrote:
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


Read the argument you previously made again. Your point was that aerodynamics of the frame itself does not, practically matter. This is a bold and yet broad statement. Hence my reply and the quote: non-aero frames and aero frames have differences.

Only after youngs_modulus reply, you said AMONG aero frames, there are little differences.

So far you have made two statements, which do not necessarily hold the same meanings. So which argument do you want to stick with? Because it sure wasn't clear enough for me.


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Posted: Wed Nov 15, 2017 5:29 pm 


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PostPosted: Wed Nov 15, 2017 5:33 pm 
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You quote me but you don't even read my quote:

kgt wrote:
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


I will not argue with you neither will I reply to your comments. You are free to believe whatever you want but please do not distort whatever I write.

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