"The Stability of the Bicycle"

The best idea!

But 'background' is needed to understand observations and most here are just
bicyclists (tm).

wrote in message
...

Don't! There is more to be gained by intelligent observation of
natural phenomena.

Jobst Brandt

wrote in message
...
Simon Brooke writes:

There are a few simple tests that he didn't do, one of which is to
wheel the bicycle along a walking speed holding on to the saddle
only. Most bicyclists have done this and those who were interested
will note that it works by gyroscopic force and not working at all
with no wheel rotation.

the effects of the steering geometry doesn't work with the bike stationary
either.

Uhhhmmmm...

I habitually wheel bicycles with one hand on the saddle. I've always
assumed that this worked in exactly the same way as riding a bike -
i.e. lean to steer. Although I agree that in principle a rotating
wheel has a gyroscopic effect at whatever speed it's rotating (and a
fast spinning wheel a considerable one) I don't believe that there's
much gyroscopic effect at this speed.

Take the wheel out, spin it in you hands and try to tilt it to the
left or right and note the force of the steering action. This should
convince you of its effect. You don't need to solve differential
equations.

That's true, but does it prove thats what keeps the bike upright?
Does it prove that the force you feel with a wheel is strong enough to keep
a bike upright (esp with the extra forces of a rider).

The "push a bike" experiment doesn't eliminate the effect of steering
geometry.

Does a bike with twice the rotating mass have the same stability at half the
speed?

There is more to be gained by
sending the researcher an electric motor and duh computer set up.
call macarthur!!!
we gotta get to the bottom of this.
or its intersections!
avast the skew!

wrote in message ...
Phil Holman writes:

The greater mass of the wheel, handlebars etc. forward of the
steering axis compared to the rear of the steering axis is the
reason for the low speed steering when wheeling and leaning a
bicycle. This is the case when the bicycle is stationary also. Gyro
forces do not become dominant until much greater speeds.

I can see you are hypothesizing. Take the wheel out,spin it in your
hands, and try leaning it from side to side. If you don't believe the
strong steering forces you experience, try steering the bicycle while
holding it by the saddle when it isn't rolling. You'll notice it does
not steer.

No I'm not hypothesizing, if the lean is initiated quickly with a
stationary bicycle the steering will go in the reverse direction and
when the lean angle is reached the mass imbalance will make the wheel
turn in the required direction. Initiating the lean very slowly will
reduce the reverse steering affect. One technique of steering a
wheeled bicycle at low speed is by rapid leaning with overtravel and
then lean reversal (whiplash) to steer the wheel in the required
direction.

Phil Holman

Phil Holman



Jobst Brandt

Phil Holman writes:

The greater mass of the wheel, handlebars etc. forward of the
steering axis compared to the rear of the steering axis is the
reason for the low speed steering when wheeling and leaning a
bicycle. This is the case when the bicycle is stationary
also. Gyro forces do not become dominant until much greater
speeds.

I can see you are hypothesizing. Take the wheel out,spin it in
your hands, and try leaning it from side to side. If you don't
believe the strong steering forces you experience, try steering the
bicycle while holding it by the saddle when it isn't rolling.
You'll notice it does not steer.

No I'm not hypothesizing, if the lean is initiated quickly with a
stationary bicycle the steering will go in the reverse direction and
when the lean angle is reached the mass imbalance will make the
wheel turn in the required direction. Initiating the lean very
slowly will reduce the reverse steering affect. One technique of
steering a wheeled bicycle at low speed is by rapid leaning with
overtravel and then lean reversal (whiplash) to steer the wheel in
the required direction.

I notice you didn't respond to the initial proposal that gyroscopic
forces, even at low speed, make wheeling the bicycle holding onto only
the saddle, possible. This is done without any tricks or sudden
motions using the rotating wheel as a steering control.

Jobst Brandt

wrote in message
...
Phil Holman writes:

The greater mass of the wheel, handlebars etc. forward of the
steering axis compared to the rear of the steering axis is the
reason for the low speed steering when wheeling and leaning a
bicycle. This is the case when the bicycle is stationary
also. Gyro forces do not become dominant until much greater
speeds.

I can see you are hypothesizing. Take the wheel out,spin it in
your hands, and try leaning it from side to side. If you don't
believe the strong steering forces you experience, try steering the
bicycle while holding it by the saddle when it isn't rolling.
You'll notice it does not steer.

No I'm not hypothesizing, if the lean is initiated quickly with a
stationary bicycle the steering will go in the reverse direction and
when the lean angle is reached the mass imbalance will make the
wheel turn in the required direction. Initiating the lean very
slowly will reduce the reverse steering affect. One technique of
steering a wheeled bicycle at low speed is by rapid leaning with
overtravel and then lean reversal (whiplash) to steer the wheel in
the required direction.

I notice you didn't respond to the initial proposal that gyroscopic
forces, even at low speed, make wheeling the bicycle holding onto only
the saddle, possible. This is done without any tricks or sudden
motions using the rotating wheel as a steering control.

I don't know what you imply by this statement. Gyroscopic forces are in
play as long as the wheel is rotating. At what speed the gyroscopic
force overcomes the mass imbalance may be a more constructive line of
investigation.

Phil Holman


Jobst Brandt

Take the wheel out, spin it in you hands and try to tilt it to the
left or right and note the force of the steering action. This should
convince you of its effect.

please explain. gyro reaction is _90 degrees to the applied force_.
i.e. my front wheel, spinning "forwards" tries to tilt top rightwards
when turned to the left. you seem to be implying that gyro recation is
responsible for banking the bike to the left when steered left.

jb

jim beam wrote:

Take the wheel out, spin it in you hands and try to tilt it to the
left or right and note the force of the steering action. This should
convince you of its effect.


please explain. gyro reaction is _90 degrees to the applied force_.
i.e. my front wheel, spinning "forwards" tries to tilt top rightwards
when turned to the left. you seem to be implying that gyro recation is
responsible for banking the bike to the left when steered left.

No, when you wheel the bike along holding onto the seat you steer by
banking the bike and the turn is a reaction to the bank. Banking the bike
to the left will tend to initiate a turn to the left. But the gyroscopic
force is quite small when the wheel is spun at only walking speed and the
geometry of the bike also results in the wheel turning left in response to
a left bank (even when the wheel isn't rotating). I'd have to try this
with a counter-rotating second front wheel (like on URB I) before
concluding which is the dominant effect.

wrote in message ...

Take the wheel out, spin it in you hands and try to tilt it to the
left or right and note the force of the steering action. This should
convince you of its effect. You don't need to solve differential
equations.
OK, but envision a system without any rotating elements. Substitute a
runner or blade shaped essentially the same as the bottom of a wheel
and substitute sliding for rolling. Such a device would still have a
turning capability without the existence of any gyroscopic effect.

Don't! There is more to be gained by intelligent observation of
natural phenomena.
You mean it's OK to be able to "feel" something even if you can't
prove it exists mathematically?

DR

Jim Beam writes:

Take the wheel out, spin it in you hands and try to tilt it to the
left or right and note the force of the steering action. This
should convince you of its effect.

please explain. gyro reaction is _90 degrees to the applied force_.
i.e. my front wheel, spinning "forwards" tries to tilt top
rightwards when turned to the left. you seem to be implying that
gyro recation is responsible for banking the bike to the left when
steered left.

Not at all. I suggest that the wheel spinning forward steers to the
left when tilted to the left and to the right when tilted to the
right. This is the means by which the bicycle steers when walking the
bike while held by the saddle and also what enables it to be ridden
no-hands.

Jobst Brandt