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"The Stability of the Bicycle"



 
 
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  #1  
Old October 5th 03, 07:12 AM
GerryK
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Default "The Stability of the Bicycle"

There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by David
E. Jones entitled, "The Stability of the Bicycle". I am trying to get a
copy. Is it, perhaps, somewhere on the internet? Advice appreciated.

Gerry


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  #2  
Old October 5th 03, 07:19 AM
Sorni
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"GerryK" wrote in message
news:[email protected]
There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by

David
E. Jones entitled, "The Stability of the Bicycle". I am trying to get a
copy. Is it, perhaps, somewhere on the internet? Advice appreciated.


Google is your huckleberry.


  #3  
Old October 5th 03, 09:03 AM
Q.
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Default "The Stability of the Bicycle"

http://ist-socrates.berkeley.edu/~fa...es/JonesBikeBW.
pdf

C.Q.C.

"GerryK" wrote in message
news:[email protected]
There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by

David
E. Jones entitled, "The Stability of the Bicycle". I am trying to get a
copy. Is it, perhaps, somewhere on the internet? Advice appreciated.

Gerry




  #4  
Old October 5th 03, 05:24 PM
Q.
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Default "The Stability of the Bicycle"

Sorry, for some reason that link didn't come out right when I posted.

You can get it from he

http://socrates.berkeley.edu/~fajans.../bicycles.html

And google was the way I found it.

I read it last night, it is a great article.

C.Q.C.

"Q." wrote in message
news

http://ist-socrates.berkeley.edu/~fa...es/JonesBikeBW.
pdf

C.Q.C.

"GerryK" wrote in message
news:[email protected]
There was an article in "Physics Today" for 1970, 23(4), pp. 34-40 by

David
E. Jones entitled, "The Stability of the Bicycle". I am trying to get a
copy. Is it, perhaps, somewhere on the internet? Advice appreciated.

Gerry






  #5  
Old October 5th 03, 08:48 PM
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Default "The Stability of the Bicycle"

anonymous writes:

http://socrates.berkeley.edu/~fajans.../bicycles.html


or: http://tinyurl.com/pswa

I read it last night, it is a great article.


I can't imagine you read all that because it wallows around endlessly
in unclear descriptions of what was tried and what results he got.
For instance, try to find whether the bicycle with a counter-rotation
wheel next to the front wheel was controllable riding no-hands and
how it was different. I read that part several times and am still
unclear about what he found.

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.

It is this kind of omission and the wandering prose that give this
report minimal credibility for me.

Jobst Brandt

  #6  
Old October 6th 03, 12:35 AM
Simon Brooke
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Default "The Stability of the Bicycle"

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.


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.

Indeed, this seems to me to be borne out by the fact that one of my
bikes which has a noticable tendency to pull left[1] can be wheeled quite
happily one hand on the saddle - but only if tilted slightly right.

However I haven't done the maths and am just going on perceptions. Has
anyone done the maths for this?

[1] The routing of the lockout cable for the rear shock isn't to
clever and the springyness of the sheath pushes on the bars.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
Ye hypocrites! are these your pranks? To murder men and give God thanks?
Desist, for shame! Proceed no further: God won't accept your thanks for murther
-- Roburt Burns, 'Thanksgiving For a National Victory'
  #8  
Old October 6th 03, 07:45 AM
[email protected]
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Default "The Stability of the Bicycle"

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.


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.

Indeed, this seems to me to be borne out by the fact that one of my
bikes which has a noticeable tendency to pull left[1] can be wheeled
quite happily one hand on the saddle - but only if tilted slightly
right.


That puts the required bias into it but steering is done by gyroscopic
forces, trail taking care of the lean offset.

However I haven't done the maths and am just going on
perceptions. Has anyone done the maths for this?


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

Jobst Brandt

  #9  
Old October 6th 03, 07:48 AM
[email protected]
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Default "The Stability of the Bicycle"

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.

Jobst Brandt

  #10  
Old October 6th 03, 08:07 AM
Benjamin Lewis
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Default "The Stability of the Bicycle"

jobst brandt wrote:

anonymous writes:

http://socrates.berkeley.edu/~fajans.../bicycles.html


or: http://tinyurl.com/pswa

I read it last night, it is a great article.


I can't imagine you read all that because it wallows around endlessly
in unclear descriptions of what was tried and what results he got.
For instance, try to find whether the bicycle with a counter-rotation
wheel next to the front wheel was controllable riding no-hands and
how it was different. I read that part several times and am still
unclear about what he found.


,----
| Gingerly, and with great trepidation, I tried the experiment --
| downhill, to avoid complicating the effort with pedalling. URB I is not
| an easy bicycle to ride "hands off" even with the front wheel static; it
| somehow lacks balance and responsiveness. In the disrotatory mode it was
| almost impossible and invited continual disaster, but it could, just, be
| done.
`----

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips
over, pinning you underneath. At night, the ice weasels come."
--Matt Groening
 




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