yaw angle for race conditions

[ada@prorider.or]

i read some comments on differant forums about unbeleive
that a yaw angle let say 30 psi ever accour


people do not realize that calc yaw angle change´s with air speed or with riding speed
i guess that most people think must be a steady wind coming from one angle wich is certainly not the case a vector that is a result of true gound speed and air speed and the angle of attack of air
i agree its only intersting for race ´s under us
but seen on the privat mail i get still a lot on this forum

the yaw angle is calc you choose the optimium for that yaw angle so called form factor in aerodynamic world

yaw angle can happen at any angle up to 90


:banana:

[Argos]

Do you think they only test up to 30 degrees (+/- usually) because if it is more then that with the riders assumed speed factored in, then it is really howling* (the wind) and wheel aerodynamics take a back seat to rider survival?

Like this. Pretend I am fast, and pretend I am good at math and common sense.

If I go to a TT and the wind is calm, or even 10 to 15 from the side, then with me riding 25mph (I said pretend), the percieved yaw is less then 30 degrees...

But if I go to the same course and cats are getting blown across the road, and there are gusts to 35-40mph, wouldn't I be reconsidering my wheel choice or bike choice?

Sorta like that day in the tour a few years ago when they did the TTT and a portion of it was across that beautiful Bridge. The team cars were illegally blocking the wind for some of the riders (I think ONCE). If the whole course was that windy, wouldn't they have used a different wheelset?

So, isn't just that there testing is testing under most ideal/reasonable use conditions?

Thanks.



*Blowing

(Hope my spelling is ok :rolleyes: )

[wanderingwheel]

Like Argos said, in order to get to a 30deg yaw angle, you need a pretty significant wind. At 25mph, the lowest wind speed to get to a yaw angle of 30deg is 12.5mph, and that's a quatering tail wind which will actually reduce your apparent wind to 21.5mph. A true cross wind (90deg) must be 14.5mph to get to a yaw angle of 30. One more thing to remember is that these are surface wind speeds. The wind speeds you see in a weather report are at 10m above the ground, assuming the ground is perfectly flat and smooth. In the best of conditions (or worst in my case), the wind that you feel on the bike will be about 75% of the reported wind speed. More commonly, the ground wind is about half of the reported wind.

[ada@prorider.or]

i i try to explain
with 50 km/h and tail wind at 150 degrees with wind speed 30 km/h you have 32 psi

make´s any sense

????????????

this way you coiche with wheel is best

since the risk of front disc wheel with wind you can be blow of the bike
so wich wheel sould i take?
that is what is for

o i forgot
we measure wind speed at riders level personly on the course

so we can plot the course look at the weather forecast
and hope all goes right
and win of course

[Argos]

i i try to explain
with 50 km/h and tail wind at 150 degrees with wind speed 30 km/h you have 32 psi


But if you are traveling faster then the wind speed, like in this example, would it not rotate back over to closer to significantly less than 30 degree yaw @ 20km/h from the front?

Then, are we not again at a shallow yaw example and back to more straightforward aerodynamic decisions?

I'd Love to TT with a 30kph Tailwind!

[ada@prorider.or]

I'd Love to TT with a 30kph Tailwind!


well this happens more then you think
at 30 km/h back wind is not much

say end of 4 beaufort
begin 5

here in holland happens a lot altough when i am riding smeems that i always have head wind tough

this is waves with white head (sorry do not know else to decribe this)

[Argos]

this is waves with white head (sorry do not know else to decribe this)

That's darn close for a guess. Where I grew up, it was called "White Caps".

I get you though.

When I lived in NY, there was a thing that I called the "Long Island Tailwind". No matter which way I rode.... It was a Headwind!