Aero

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kgt
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by kgt

From:
http://rouleur.cc/journal/bicycles/pro- ... ate-cf-slx

Some wise inside comments on what really matters in pro cycling performance:

The aero bike or the climbing bike? Di2 or mechanical transmission? 40mm rims or 60mm? The fixed, one-piece carbon cockpit, or the greater field of adjustment offered by a conventional aluminium bar and stem? For Andreas Walzer, Canyon's team liaison to Katusha and Movistar, it is almost entirely a matter of rider psychology. “The riders have to believe, and this is more important than anything else,” he says. “If they are confident that they have the best material, that they have chosen it, that they have changed the position of the levers, for example, then they are ready.”

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Tapeworm
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by Tapeworm

We've now switched from science and engineering to psychology! :lol:
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
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kgt
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by kgt

Psychology is a science and it matters much more than other sciences in this case 8)

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Samuel Sanchez Gonzalez
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by Samuel Sanchez Gonzalez

Great table Tapeworm.

I'm surprised gravity equals drag as soon as 2% because 300W is supposed to be quite high speed there.

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Tapeworm
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by Tapeworm

@Sammy SG - thanks, but full credit for the chart is Alex Simmons @ RST.

And, yes, the chart assumes a constant *power*, the weight becomes highly significant. At higher power outputs (and hence speed) the aero factors would increase, but not by much.
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
"I'm not a real doctor; But I am a real worm; I am an actual worm." - TMBG

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Tapeworm
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by Tapeworm

kgt wrote:Psychology is a science and it matters much more than other sciences in this case 8)


So, now bikes go slower or faster based on... belief now? And I thought all this time it was power! Nope, good intentions make you go faster! :roll:
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
"I'm not a real doctor; But I am a real worm; I am an actual worm." - TMBG

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Calnago
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by Calnago

Tapeworm wrote:...
As per this excellent chart done by Alex Simmons of RST
Image

For the most part I am so done with this thread, but I find this chart quite interesting and would just like some clarification on it. One of the assumptions is that it is 300W, but it makes no mention of speed.
Seems that 300w at zero gradient would be a very high speed, versus 300watts on a steep gradient could be much much lower speed. Since the air resistance is much higher at 30mph than say 15mph, how does that factor into this chart? Just curious. Surely it can't be assuming a constant 30mph whether you're on a flat grade of 0% versus a steep grade of 15%??
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maquisard
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by maquisard

Calnago wrote:For the most part I am so done with this thread, but I find this chart quite interesting and would just like some clarification on it. One of the assumptions is that it is 300W, but it makes no mention of speed.
Seems that 300w at zero gradient would be a very high speed, versus 300watts on a steep gradient could be much much lower speed. Since the air resistance is much higher at 30mph than say 15mph, how does that factor into this chart? Just curious. Surely it can't be assuming a constant 30mph whether you're on a flat grade of 0% versus a steep grade of 15%??


Surely the chart is very intuitive, it assumes 300W input power.

So on the flat, speed is greater, say 30mph, so most of the energy is spent overcoming air resistance. Hence on the flat aero benefits, e.g. position, frame, helmet etc will have a major difference.

On a steep incline, speed is lower, less power is spent over coming air resistance and more spent on overcoming gravity, so aero benefits are less worthwhile.

The most important point, constant power does not equal constant speed!

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ergott
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by ergott

Calnago wrote:Surely it can't be assuming a constant 30mph whether you're on a flat grade of 0% versus a steep grade of 15%??


There is no assumption of constant speed, just constant power. That's why aero resistance is so much more of the total resistance on more flat terrain where you are going faster. I like that chart because I can relate to the power output if only for relatively brief periods (compared to a pro's threshold).

It really shows that the importance of aero really depends on the course. It doesn't have to be that steep for weight to be a bigger concern.

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Calnago
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by Calnago

Thanks @maquisard. Now that I study it a bit more I get it. I've seen charts like this before but this one is quite nice. So, what it seems to be telling me is that for anything under a 2% grade aero is king, which explains why a big powerful guy isn't at such a disadvantage on flat terrain compared to the ultralight climber. Very intuitive (I like that). But for anything over a 2% grade, then the tables turn dramatically and in fact on a 5% grade it takes about 5 times the power to overcome gravity than it does air resistance, minimizing any real benefit from aero properties, which also makes sense (I like stuff that makes sense). Hmmm, for my money, this chart tells me, for the kind of riding I most engage in (varied terrain, not all flat and certainly a lot of 3-6% grades) that aero is very secondary to getting in better shape and dropping a few lbs/kg off my fat ass as soon as possible. Since I'll be doing Ride The Rockies in June, I'd best pick up my schedule and actually start training a bit instead of just riding around.
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Calnago
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by Calnago

@ergott: yes, just saw your reply after I posted above. Same conclusion as you I believe. Thx.
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7ducati
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by 7ducati

Calnago wrote: that aero is very secondary to getting in better shape and dropping a few lbs/kg off my fat ass as soon as possible.


Or you could go aero AND lose weight, and ride even faster. 8)
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Calnago
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by Calnago

Not uphill, benefit is immaterial. And even more so if your combined rider plus bike weight is over 75kg (the chart assumption), which is the case for me. No more donuts for awhile! [emoji3]
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7ducati
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by 7ducati

No more donuts? Now you are talking crazy.
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ergott
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by ergott

Calnago wrote:Not uphill, benefit is immaterial. And even more so if your combined rider plus bike weight is over 75kg, which is the case for me. No more donuts for awhile! [emoji3]


Yeah, but a bike like the Madone is a great all around race bike that probably has enough aero benefits to consider over some of the other offerings that aren't all out aero bikes. I'd take one over a Tarmac or 'Dale for that reason. Madone with full aero bits (medium depth aero wheels) would still be a great climbing machine and the ride quality is very good. I took a Madone 7 out for a long spin and that's a seriously nice bike.

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