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PostPosted: Tue Feb 28, 2012 2:58 am 
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Posts: 107
Valbrona wrote:
justkeepedaling wrote:
0-180? What the hell are you talking about. Are cyclists now riding in reverse?


Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.


...maybe for YOU :roll:


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Posted: Tue Feb 28, 2012 2:58 am 


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PostPosted: Tue Feb 28, 2012 3:08 am 
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Posts: 1512
Valbrona wrote:
justkeepedaling wrote:
0-180? What the hell are you talking about. Are cyclists now riding in reverse?


Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.


What? Vectors has nothing to do with magnitude. You can calculate yaw whether you are traveling at 1mph or 100mph.

I've seen data which suggests less than 10% of all wind is over 20mph.

Anyway, play with this calendar and then talk to us about 180 degree wind:
http://www.wing-light.de/TechTalk/yaw.htm


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PostPosted: Tue Feb 28, 2012 3:10 am 
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Epic-o wrote:
JamieL wrote:

Image



I'm so surprised the Catlike faired so well in that test, I swear it makes my neck hurt in the crosswinds it catches so much air, but in South Texas from April-October it's totally worth it!!! :thumbup: :thumbup: :thumbup:


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PostPosted: Tue Feb 28, 2012 3:44 am 
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Posts: 188
Valbrona wrote:
justkeepedaling wrote:
0-180? What the hell are you talking about. Are cyclists now riding in reverse?


Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.

Yes, wind comes from all directions, but when are you ever travelling slower than the wind? The yaw angle you care about is the direction of the air relative to the rider. Unless you aren't pedalling for some reason, that will most likely be between 0-30 deg.


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PostPosted: Tue Feb 28, 2012 6:34 am 
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Posts: 1118
Location: Gold Coast, QLD, Australia
bricky21 wrote:
Murphs wrote:
The Kask helmets are filled in like that, that is not a helmet cover. Sky have been using them for a number of years in the classics etc

Removable covers are illegal however.


Which model? The Sky rider behind looks to be using a standard helmet. I can't find that helmet on the Kask website, but I can't find a helmet cover either. Iirc Cav was wearing a cover in the WC road race on his specialized prevail.


Just because they're wearing one, doesn't mean you can buy one.

There was some murmur that if the UCI had actually seen Cav's helmet cover before the RR started, it would have been disallowed, but they didn't.

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PostPosted: Tue Feb 28, 2012 9:18 am 
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Location: Pedal Square
Valbrona wrote:
justkeepedaling wrote:
0-180? What the hell are you talking about. Are cyclists now riding in reverse?


Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.

I'm not sure how relevant the 180° yaw case is though -- anyway you would probably like to have a high drag in that case, so you catch more air and sail off the front of the group! :beerchug:

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PostPosted: Tue Feb 28, 2012 12:38 pm 
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Location: Lyon
Valbrona wrote:
Vector analysis works with objects that move at higher speed than your average cyclist.


:roll: :roll:

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PostPosted: Tue Feb 28, 2012 1:04 pm 
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Roeboe wrote:
I think the main reason is for keeping the head wind and water free, since you lose most energy (heat) trough your head.


Myth!:

http://www.guardian.co.uk/science/2008/ ... nbehaviour

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PostPosted: Tue Feb 28, 2012 2:22 pm 
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Joined: Mon May 24, 2010 4:18 am
Posts: 361
Location: Australia
Have had my prevail for a year now - would not rate it very well for two reasons:
Build quality is very very ordinary compared to my met strad. Moldings are very poor with days hanging off. Stickers are peeling. Typical made in china effort cleverly disguised with a made in Macau sticker - never again!
2. Chin straps vibrate when over 30kmh. Have tried tightening as per instructions but they loosen promptly and start buzzing again.

Just my thoughts. Some love it and swear by it and I respect that.
Peace
I


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PostPosted: Wed Feb 29, 2012 8:55 pm 
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Location: Wherever there's a mountain beckoning to be climbed
It may not be as common as [0,30], but [90,180] yaw is possible on a bike. For example, strong predominantly tail wind up a steep climb. And yes, vector analysis applies regardless of speed, as long as you know how to apply it.


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PostPosted: Wed Feb 29, 2012 10:11 pm 
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Location: Netherlands
I think the closed helmets are not for aerodynamics, but to keep the wind (thus cold) out!

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PostPosted: Wed Feb 29, 2012 10:20 pm 
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rodebaron51 wrote:
I think the closed helmets are not for aerodynamics, but to keep the wind (thus cold) out!


They do both.


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PostPosted: Thu Mar 01, 2012 8:31 pm 
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Location: Austin, Texas
Vector analysis works just fine and dandy for objects as slow as cyclist - even one as slow as myself.

http://s321476941.online.de/hedgermany/ ... ulator.asp


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PostPosted: Thu Mar 01, 2012 8:40 pm 
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Joined: Thu Nov 17, 2011 8:26 pm
Posts: 246
Location: Norway
Valbrona wrote:
justkeepedaling wrote:
0-180? What the hell are you talking about. Are cyclists now riding in reverse?


Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.


What the hell are you talking about? 360 degrees almost only applies when the rider is standing still. You don't have to ride very fast before airflow relative to the rider never exceeds 20 degrees of yaw.


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PostPosted: Thu Mar 01, 2012 9:13 pm 
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Location: Russia, Moscow
hna, 'never' is a rather strong word, isn't it? Try playing with the Apparent Wind Calculator from the link above (it's buggy in km/h, so leave it in mph) - you'll see that it's entirely possible to have sidewind of more than 20 degrees.


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Posted: Thu Mar 01, 2012 9:13 pm 


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