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Originally Posted by KenWittlief
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using the front wheel of a bike as a reference, when the wheel is spinning if you turn the handlebars to the LEFT the gyroscopic effect makes the bike lean to the RIGHT...
...This is what makes a bike balance on its own, if the bike starts to fall over the front wheel turns to correct the fall (turns into the fall).
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If you have two flywheels spinning in opposite directions, the gyroscopic effect is completely canceled out. Ive seen bicycles rigged up with a wheel on top of the front and back wheels, so that as you ride they spin backwards. The bike is almost impossible to ride, and if you give it a forward motion shove by itself, it falls right over.
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This idea is a common idea that is just plain wrong.
If you read my unsung FIRST Hero response (
Dr. Joe Speaks) you will see that one of the non-random whacks in my life is
R.E.Klien.
He has made bicycle stability one of his life's works.
Here is a zero-gyro bicycle.
I assure you it is easily ridden.
The reason a bicycle stays up is complex, but it is MOSTLY due to the forward rake angle of the steering fork and the positive caster of the front wheel (positive caster is when the point of contact of the wheel is behind the line where the steering axis intersects the ground).
In its simpliest form a bike does not fall because these two factors elegantly conspire to provide a stable steering angle that will put the bike in a circular arc where the gravity moment trying to make the bike fall is exactly cancelled by the centripital acceleration. Above a critical speed, the fork & wheel geometry provide a stable feedback mechanism that keep the bike from falling.
Go
Here and
Here and
Here for more detailed explanations of why a bike does not fall and why gyroscopic effects an negligible compared to other factors.
Joe J.