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PostPosted: Tue Mar 14, 2017 12:01 am 
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https://www.youtube.com/watch?v=h0BH3wXzhrI


impressed with bikeradar performing more analytical tests in the lab.

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Posted: Tue Mar 14, 2017 12:01 am 


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PostPosted: Tue Mar 14, 2017 12:28 am 
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Location: Az USA
Interesting to see the CLX64s so low, I figured they'd be at least mid pack but the test makes me happy that I bought some HED Jet 6+/9+ a few years ago and they're still fast as hell (although I wish I had those black brake tracks :cry: )


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PostPosted: Tue Mar 14, 2017 9:16 am 
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Location: Vienna Austria
Don't have the nerve to watch a 12 min video, but in the table at the end they don't show 0° yaw numbers?

I don't ride my bike at 5° or 12.5° usually as I prefer riding straight ahead, so this is a joke.

It's time someone admitted that all the wheel aero magic isn't worth much when going fast in low wind, and that wide wheels and tires will slow you down most of the time.


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PostPosted: Tue Mar 14, 2017 9:57 am 
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And have the cheap narrow chinese wheel win?

That'll go down well with the advertisers :)


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PostPosted: Tue Mar 14, 2017 10:24 am 
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Location: Jyväskylä, Finland
Marin wrote:
Don't have the nerve to watch a 12 min video, but in the table at the end they don't show 0° yaw numbers?

I don't ride my bike at 5° or 12.5° usually as I prefer riding straight ahead, so this is a joke.

It's time someone admitted that all the wheel aero magic isn't worth much when going fast in low wind, and that wide wheels and tires will slow you down most of the time.


I would like to live where you live, a paradise where there is no wind.


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PostPosted: Tue Mar 14, 2017 11:28 am 
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Location: Hampshire, England
Marin wrote:
wide wheels and tires will slow you down most of the time.


Uh?


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PostPosted: Tue Mar 14, 2017 12:37 pm 
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Location: Vienna Austria
guyc wrote:
Uh?


Uh-huh.

When you go in a straight line and there isn't a strong side wind, a narrow tire and rim has a smaller frontal area and thus lower aerodynamic resistance. It's so logical that it seems almost strange in the current marketing hype.

If you look at the popular yaw charts, you will see them overlap in the middle, meaning that there isn't a lot of difference between wheels when the wind comes from the front.

There is very little actual field yaw data available, and much of it comes from manufacturers who have an interest in presenting high-yaw (i.e. sidewind) conditions because only these will help them sell wide wheels.


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PostPosted: Tue Mar 14, 2017 12:48 pm 
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Location: Hampshire, England
And rolling resistance?


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PostPosted: Tue Mar 14, 2017 1:49 pm 
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Wide tires are harder at identical pressures, and if you lower pressure to achieve equal ride comfort, the advantage in rolling resistance is quite small.

Additionally, rolling resistance rises linearly, while air resistance rises with the square of speed, so if you go fast, aerodynamics dominate rolling resistance.

That's why you won't see time trialists or track riders on wide tires.


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PostPosted: Tue Mar 14, 2017 2:09 pm 
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Location: Blacksburg, VA
Marin wrote:
Wide tires are harder at identical pressures, and if you lower pressure to achieve equal ride comfort, the advantage in rolling resistance is quite small.

Additionally, rolling resistance rises linearly, while air resistance rises with the square of speed, so if you go fast, aerodynamics dominate rolling resistance.

That's why you won't see time trialists or track riders on wide tires.


Except Tony Martin, riding 25mm clinchers.

So much for that theory, eh?

Sent from my XT1585 using Tapatalk


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PostPosted: Tue Mar 14, 2017 3:15 pm 
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LeDuke wrote:
Sent from my XT1585 using Tapatalk


Everyone is running 25mm now, but not wider. I doubt we'll see anyone adopting 28+ for the road, even though rim manufacturers are starting to push 21c rims.

However, IIRC Tony Martin was running staggered clinchers in 24mm / 26mm. The S-Work Turbos don't come in 25.


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PostPosted: Tue Mar 14, 2017 3:19 pm 
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Marin wrote:
LeDuke wrote:
Sent from my XT1585 using Tapatalk


Everyone is running 25mm now, but not wider. I doubt we'll see anyone adopting 28+ for the road, even though rim manufacturers are starting to push 21c rims.

However, IIRC Tony Martin was running staggered clinchers in 24mm / 26mm. The S-Work Turbos don't come in 25.

The 24s measure out at 25mm on many wheels.

Point being, 19s, 20s and 21s used to be the name of the game for TTs. Many tires aren't even made in 21mm widths anymore.

Sent from my XT1585 using Tapatalk


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PostPosted: Tue Mar 14, 2017 3:23 pm 
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Location: Vienna Austria
It's a trend, like bikes getting heavier every year.

It's very important for manufacturers to make or label components as incompatible so you e.g. have to buy not only wider tires because they "roll faster" but also wider rims to make the sidewalls "less of a bulb shape" etc.

Give me a good reason for the bikeradar test not even measuring at 0° yaw :)


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PostPosted: Tue Mar 14, 2017 3:30 pm 
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Location: Blacksburg, VA
Marin wrote:
It's a trend, like bikes getting heavier every year.

It's very important for manufacturers to make or label components as incompatible so you e.g. have to buy not only wider tires because they "roll faster" but also wider rims to make the sidewalls "less of a bulb shape" etc.

Give me a good reason for the bikeradar test not even measuring at 0° yaw :)

Because if you have ANY wind at all, aside from dead on headwind or tailwind, you'll see angles >0°.

Imagine a scenario where you are riding in the Midwestern US. All the roads there are on a grid, aligned more or less perfectly on the cardinal directions, and in 1mi x 1mi squares. If you are riding due west, how often to you think you'd encounter a wind that is coming from 270°? And how often would it be anywhere from 180-360°? Or, 225-315°?

Yaw angles of 5-20 degrees are measured because they are more realistic conditions than 0°. Still air or a dead on headwind are a statistical anomaly.

Sent from my XT1585 using Tapatalk


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Posted: Tue Mar 14, 2017 3:30 pm 


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PostPosted: Tue Mar 14, 2017 4:05 pm 
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Posts: 154
LeDuke wrote:
Marin wrote:
Yaw angles of 5-20 degrees are measured because they are more realistic conditions than 0°. Still air or a dead on headwind are a statistical anomaly.


http://www.slowtwitch.com/images/trek/TK13_SC_Whitepaper_final.pdf
http://flocycling.com/aero.php

You are of course welcome to be skeptical of these data sets as maybe they're tailored to fit an agenda. Of course wider angles happen, but I think it's an error to call them prevalent.

I had a unique opportunity to ride with the top US Ironman athlete days before he headed to Specialized's Win Tunnel to do his aero testing in prep for the 2014 season. Ironman triathletes are maybe the people most concerned about aerodynamics out of all cyclists. I asked him the direct question of what sweep range he planned to test, to which he replied that he'd only test -10* through +10*. Angles outside of 10* aren't seen in enough concentration to be concerned with them. By which I mean that they happen, but the clusters of incidence happen at low angles. The athlete in question had free access to the tunnel as he was sponsored by Specialized, so this wasn't a question of resource constraint.

Take that for what it's worth.

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