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Old October 7th 03, 05:53 PM
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Default "The Stability of the Bicycle"

Jim Beam writes:

wow. you've just completely rewritten the world of physics.
absolutely extroardinary.


You'll have to be more explicit. What is it that you find
extraordinary and contrary to "the world of physics"?

Look, take a bike wheel, suspend one end of the axle from a piece of
string, then spin it in the normal vertical position. The wheel will
appear to "defy gravity" by remaining near vertical with its axis
perpendicular to the string. Then you will notice that the wheel axis
is itself rotating around the string. This is because the reolved
resoulution of simple newtonian physics resolves at 90 degrees to the
applied force, i.e. the string pulls up against the wheel's center of
gravity axis, so the wheel moves at 90, thus rotating.


In spite of the garbled text, I don't see in what way this contradicts
steering a bicycle using these forces, if I deciphered it correctly.
By the way, have you performed this experiment or did you only read
about it? If you have done this, you'll note that the axle of the
wheel remains in a horizontal plane down rotation speed of the wheel
below one revolution per second.

When you tilt a fork of a bike with a rotating wheel in it, there's
no reason for the physical world to suddenly distort and suddenly
run counter to normal.


What do you mean by this. Can you translate that to plain English?

As has been described by a previous poster, a vehicle ith no rotating
components still banks & steers satisfactorily. Gyro forces DO NOT make
the bike bank.


I think you have that backwards, banking (or leaning) the bicycle to
one side or the other causes the wheel to turn, not the converse.

If you don't want to believe me [sic], just dig out that old high
school physics footage of a bike being ridden with a counter
gyroscopic wheelset. Works just fine.


I'm not familiar with your "footage".

Jobst Brandt

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