wind?

ggs34 · Post by **ggs34** » Wed Apr 10, 2013 8:08 pm

this may be a dumb question but does any one know how much wind will slow you down?

example.top speed on my buddy was 65 so if an have a head wind of 30 mph how much would it slow me down?

does any one know how to do the figure this out?

skully93 · Post by **skully93** » Wed Apr 10, 2013 8:16 pm

given that wind is rarely a constant, I don't think you could figure out an exact formula.

I know that I like riding with the wind much better than against it, especially from the side!

TVB · Post by **TVB** » Wed Apr 10, 2013 8:19 pm

It's complicated, depending on how tall you are, how wide you are, how much wind your clothing grabs, etc. A windshield will help to some extent, again depending on the size of it.

ggs34 · Post by **ggs34** » Wed Apr 10, 2013 8:27 pm

just want to be able to do 55 to 60 is a 150cc too small?
like a pcx honda 150?
i am over 6ft

gr8dog · Post by **gr8dog** » Thu Apr 11, 2013 12:21 am

In my experience on my Buddy it can be a lot. 40 to 50 top speed against that much wind. With the wind I hit 70 with more to go, but I started thinking about those small tires spinning above their rated speed and I backed off. I am 5'11" and about 200lb, Buddy has a windshield, Prima medium. Your results may vary.

Beamster · Post by **Beamster** » Thu Apr 11, 2013 1:33 am

Wind isn't so complicated. It's merely a function of wind speed and exposed area; that will result in a force. . Just think about it, every building needs to conform to standard wind loads specified in your area's Building Code.
Elementary physics formulas relate force, velocity and acceleration

TVB · Post by **TVB** » Thu Apr 11, 2013 3:54 am

Beamster wrote:Wind isn't so complicated.

Tell that the the folks at Boeing.

jrsjr · Post by **jrsjr** » Thu Apr 11, 2013 5:02 pm

On level ground your top speed is almost* entirely limited by wind resistance. Top speed by definition is the balance between the maximum horsepower at the rear wheel versus the wind resistance to the frontal area (with it's associated Coefficient of Drag) of the scooter and rider trying to push through the air. So, if your top speed on level ground is 65 and you ride directly into a 30 mph wind, your top speed will be 65 - 30. It's pretty straightforward.

Automobile drivers rarely encounter this phenomena because they never go fast enough to encounter the stasis between maximum horsepower and wind resistance - AKA "top speed." For an automobile driver, a far more common thing would be to run into a strong headwind on a steep hill and have to push harder on the throttle to make more power to maintain speed. We small scooter riders encounter much more interesting physics in the course of pushing small machines to their absolute limits!

*"Almost" because there is a small rolling resistance to the tires etc, but at top speed these factors are overwhelmed by aerodynamic effects.

still shifting · Post by **still shifting** » Thu Apr 11, 2013 5:44 pm

The last couple of days it wasn't just the wind, but the dust, sand and debris, especially those Damn plastic bags that seem to be drawn to obscuring my vision. Yet another reason to slow down in the wind. R

Maximus53 · Post by **Maximus53** » Thu Apr 11, 2013 5:50 pm

I learned the hard way that:

wind + scooter cover > force required to tip a stella off the centerstand...

ggs34 · Post by **ggs34** » Thu Apr 11, 2013 9:28 pm

thanks wow thats a lot of physics i think i got it

so you just take maxim speed and - the wind speed? right

jrsjr · Post by **jrsjr** » Thu Apr 11, 2013 10:34 pm

ggs34 wrote:thanks wow thats a lot of physics i think i got it

so you just take maxim speed and - the wind speed? right

Pretty much, yep. That's assuming a direct headwind on level ground. If the wind is hitting you at an angle, then you have to use a little trigonometry to get the component of the wind that is directly opposing your direction of travel as shown below. You can punch this directly into Google to get the result. As a reality check, assume the angle is zero, which means the wind is directly head on. Punch this into google - "cosine 0 degrees" and the answer is 1. You multiply 1 times the wind speed and it is unchanged, which agrees with your intuition. Suppose the angle is 90 degrees. Punch "cosine 90 degrees" into Google and you get 0. That means that a wind that hits you directly from the side has no effect on your forward speed. That also agrees with your intuition, right? Now, just for fun, punch in "cosine 45 degrees" and multiply that result times a realistic wind velocity, say 10 miles per hour, and see what you get. Then subtract that from your Buddy's top speed, and you'll have a sense of the effect that a random moderate headwind might have on your top speed.

This same math works the opposite way with a tailwind, except the tailwind adds to your top speed.

Stitch · Post by **Stitch** » Thu Apr 11, 2013 11:41 pm

Dude, duck down, reduce wind drag. A 150 should be able to hold 55mph in normal wind. Obviously, if you got hurricane force winds, your results may vary.

jrsjr · Post by **jrsjr** » Thu Apr 11, 2013 11:57 pm

Stitch wrote:Dude, duck down, reduce wind drag. A 150 should be able to hold 55mph in normal wind. Obviously, if you got hurricane force winds, your results may vary.

Folks who've experimented around generally agree that a flyscreen is the optimum balance between aerodynamics and reasonably upright seating position. Tucking in a bit behind the windscreen reduces the frontal area of the bike by hiding the (very unaerodynamic) rider's body behind the (lower coefficient of drag) windscreen. Channelling Sheldon Cooper.

gr8dog · Post by **gr8dog** » Fri Apr 12, 2013 12:11 am

ggs34 wrote:thanks wow thats a lot of physics i think i got it

so you just take maxim speed and - the wind speed? right

Welllll, not really quite so easy. Wind resistance increases exponentially. As an example. The wind resistance at 60mph is not double that of 30mph, it is more like 4 times as much. Therefore a 30mph headwind does not decrease your top speed by 30mph but something more like 10 to 15 mph. I don't know the actual equations but you get the idea.

weirdsong1 · Post by **weirdsong1** » Fri Apr 12, 2013 2:20 pm

Headwinds (and tailwinds) are not figured quite the same for ground vehicles as for aircraft -- at least it's not as straightforward. For ground vehicles you have to take the friction between the wheels and pavement into account, which is a far greater force than any normal wind force. Which is the reason why when you're standing still a 30 mph wind doesn't push you down the road at 30 mph, if it even moves you at all (which it would in a frictionless environment).

That said, it's pretty windy here in sfla and I have watched my speedometer drop 3-4 mph when faced with a strong, steady headwind. I've definitely come to respect the wind, which can wreak havoc on light, small-wheelbase vehicles.

olhogrider · Post by **olhogrider** » Fri Apr 12, 2013 3:35 pm

Nobody told me there would be math! I found my 150 would do 65 flat ground, no wind. In stiff 25-30 mph headwinds I got as low as 55 but never less. I did duck down. Your speed may vary as I'm a bit smaller than you.

charlie55 · Post by **charlie55** » Fri Apr 12, 2013 4:03 pm

I dunno, but this whole discussion seems kinda odd. If one is only dealing with occasional gusts then losing a couple MPH for a few seconds shouldn't be that big of a deal. If one is somehow managing to always ride into a 30 MPH headwind, then just go for the extra ccs/hp and the issue becomes moot.

Personally, I'm more concerned with crosswinds.