MeltingPlastic wrote:... - But the wheel is heavy so I believe it
Do not be confused as to what keeps the bike up, it is not the gyro torque acting on the bike that keeps it upright, it is the steering wheel that does that.
The gyro simply act as a driver.
Basically when the bike lean to one side, there is a perpetual torque that try to topple the bike.
This torque is aligned with the longitudinal axis of the bike.
The wheel have an angular momentum axis that is about perpendicular to the plane of the bike.
This gravity torque and angular momentum turn the wheel into gyroscope.
Because the wheels try to preserve their angular momentum, a new torque perpendicular to the ground is produced that try to rotate the entire bike around the ground plane.
In most cases the torque is quite small, is has almost no effect on the bike, but even if it did, it. Would rotate perpendicular to the ground, so that can't be the restoring torque.
What happens is that because the front tire is on an axis that is almost aligned with the gyro torque, is the magnitud of that torque that turn the handle, like a person would.
It just happens that the turn of the front wheel is on the direction that tend to align the bike.
In a way the gyro act as a driver. This is the reason that. It does not have to be a tire, as long as there is any spinning wheel, the effect is accomplished.
Here is the interesting part that will blow your mind, the torque is bigger the smaller the angular velocity is, this is why is work at low speed.
I know you are now thinking I am crazy, but is true.
It is all about vector arithmetic.
If the gravity torque is small, the at high speed it influence on the tire angular momentum is negligible, so it does the right amount of small adjustment.
At low speed the tires angular momentum is smaller,
So now the hypotenuse is larger and turn the front wheel more.
If the gravity torque is very big, or the angular momentum is too small, the the hypotenuse align more with the gravity torque and the bike falls. So not the angular momentum can't be arbitrally small. Whis is why you bike use the wheel that the can pre spin.
If you do not believe me, run the gyro demo, you will see that the fly wheel that spin at lower speed has a larger precesing velocity.