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post #1 of 4 (permalink) Old 01-06-2004, 07:10 PM Thread Starter
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got this in my email... kind of interesting experiment...


Dear riders,

Here is some kitchen science from the Superbike School "labs".

Steering and Gyroscopes

Here is a simple experiment I did to try and figure out how much influence
the gyroscopic effect of a spinning wheel has on steering a motorcycle. I
did it a few years back and here is how it went.

I balanced a ZX6 on a floor jack so that the wheels were both off the
ground and the small cup on the floor jack (which fortunately balanced the
bike nicely on the pipe's four into one collector) wasn't significantly
restricting the bike's ability to tilt. It was balanced precisely enough so
that a slight nudge with my finger would move the bike slightly on both the
longitudinal and lateral axiis.

I took an electric drill motor with a rubber disc on it and spun the front
wheel to about 30mph.

I figured that pushing the handlebar should produce some reaction in the
bike from gyroscopic precession. A non scientific definition of gyroscopic
precession is a combination of the resistance and motion we feel when a
gyro is in your hands (like a spinning bicycle wheel held by the axle) and
the resulting direction of the twist that is produced from inputs into the
gyro at its axis.

What happened? Almost nothing. There was a vague, very slight tilting of
the bike. Whereas we know we can quickly and accurately counter steer at
30mph this, according to the simple experiment, is definitely not the
force that is making it happen.

Was this a true scientific experiment? I don't know but I do know that the
force produced was weak and would never be great enough to tilt and turn a
motorcycle.

All the best,

Keith

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post #2 of 4 (permalink) Old 01-06-2004, 08:09 PM
 
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Ummm.. ok... so what... countersteering has always been mostly about using the weight of the bike to turn. When you push on the bars, the bike is thrown off balance in the opposite direction you steer.... thereby initiating a turn. Body steering only has a limited affect, because you yourself only weigh 1/4 of what the bike does.

To understand countersteering, ride a motorcycle at 5mph or slower. Watch what steering inputs are needed to maintain your balance. you are prevnting the biek from falling over i nthe same manner you are intentionally causeing a bike to "Fall" into a turn.
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post #3 of 4 (permalink) Old 01-07-2004, 11:26 AM
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Yeah, I am a little confused by the results of the test as well. I wonder what the difference in gyroscopic forces would be if both wheels were spinning, not just the front. Even with rotors, I bet the rear would have more mass than the front and should therefore have a greater effect on the bike. Also there is the motor creating a large amount of this force as well.
My understanding of why countersteering works is that you make a smaller radius of the front tire shoulder on the ground in front and thus the a shorter radius around, and the bike turns on this new arc. Not really the best explaination in writing, but it makes sense in my head at least!!

I wish I had a garage, extra bikes, and time enough to conduct such experiments!

the uncarved stone
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post #4 of 4 (permalink) Old 01-07-2004, 09:25 PM Thread Starter
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Its over my head as well.. figured it would make for some good off season banter...

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