Riding in the wind, a snippet from the IAM newsletter
 

The Carlisle & West Cumbria IAM have a brilliant guy who produces the newletter. He was a RN Diver, and has a Physics Degree, tought High School Science and now teaches people how to drive, ride and is a IAM Senior Observer.

His party trick is explaing the physics behind why cars & bikes corner, slip angles, reaction forces, corner forces, slip force, thrust demand, camber thrust etc etc.

He put this snippet in the monthy news letter and I though you'd be interested as people often ask how to ride in the wind. Well here's the explanaition of what happens and why...


Bike Tip of the Day:
If riding in a strong cross-wind, you would expect the bike to be blown over, off the vertical, in the same direction as the side wind blows; but it doesn�t, in fact the bike does the very opposite and leans into the wind! Why�s that?
Even on a perfectly still day, there�s an airflow created by the bike�s forward motion: this is the Head Wind.
The component of the Head Wind and Side Wind add to give a greater airflow down the windward side of the bike; this reduces the pressure to below atmospheric pressure on that side; the bike is then heeled over into the sidewind by the greater atmospheric pressure on the opposite side to the wind. It�s the same principle that provides Lift on the underside of an aircraft wing: all due to the work of 18th Century Swiss Mathematical Physicist, Daniel Bernoulli.
To stop the bike leaning into the Side Wind, stick your knee out to act as an airbrake on the windward side.


This slows the airflow enough to get rid of the negative pressure; once the air pressure on either side of the bike is equalised, the bike sits upright.


Simples!

What happens when the wind is so strong it's trying to blow you off the road?

Speed up, then the 'apparent wind' (combination of head and cross wind) is less sideways and more dominated by the headwind.

Go on, I dare you.

At 80mph the 'apparent wind' was very much a sidewind. The sort of sidewind that blows trucks off course.

So my bike is like an aircraft wing!
So what happens when the wind blows from the other side?
Unconvinced
K

Where does it say that ?

speed up always helps and lower gear so your driving all the time and no looseness in bike (does that make sense)

Well its BASIC physics 101! Don't shoot the messenger. The OP is perfectly correct. I may not be able to ride my bike well but I do know the physics involved and the OP is correct.

Try this little home experiment. You will need running water through a tap and a tea spoon. Run the water, in parallel to the water, but about 1" appart hold the tea spoon from the tip of the handle with the BACK against the water. Now when you close the 1" gap to nothing you would expect the flow and pressure of the water to push the back of the tea spoon away, yes? See what actually happens, this is called 'lift' and is the principle of flight and part of the aerodynamics that the clever OP is refering to.

Learn from this man he knows what he is talking about. I don't so ignore me, lol

Keep safe and remember; 'the mind works best when used like a parachute. Open'.

Kidest,

Ryland

mmmm
 

Sounds a bit iffy to me.

Bikes aint spoon shaped.

The wind pressure has the same effect as counter steer, so the bike "leans" into it. This is a gyroscopic effect - nothing to do with aerodynamics.

What I do know is that the less you interfere and thew more you relax into the bike the better.

Please elaborate?

Counter steer is to do with the shape of the tyre and the 'rolling cone effect' causing over correction, counter steer is there is because the Camber thrust is too great (causing the bike to oversteer) for the Corner Force Demand. In other words you provide negative slip that matches the difference between the camber thrust and the corner force demand.

As opposed to a cars steering, where you cannot use negative slip, and you have to use slip force and thrust to equal the cornwer force demand.

Gyroscopic effect is an urban myth, nothing to do with how a motorcycle handles, otherwise you'd never get the bike to lean over in a bend.

It's very simple A level physics.