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Main
Date: 07 Jun 2007 03:35:54
From: Thomas Hood
Subject: The mathematical way to ride a bike
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http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
Paper here:
http://tinyurl.com/2ducg9
Apologies if this is old news,
Tom
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Date: 22 Jul 2007 10:50:04
From: Jim Papadopoulos
Subject: Re: The mathematical way to ride a bike
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On Jun 7, 2:32 pm, carlfo...@comcast.net wrote:
> On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood
>
> <thomas.h...@gmail.com> wrote:
> >http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/sci...
>
> SNIPSNIPSNIP
>
> A link to a video would be wonderful.
>
> Cheers,
>
> Carl Fogel
The aforementioned Telegraph link has a video link at the top of the
page. Do review it, to see a bicycle 'popping back up' after a shove.
Also take a look at Arend Schwab's web page with treadmill
experiments: http://audiophile.tam.cornell.edu/~als93/Bicycle/index.htm
Arend was an important contributor to the discussed paper, and so am I
Jim Papadopoulos
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Date: 22 Jul 2007 13:07:25
From:
Subject: Re: The mathematical way to ride a bike
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On Sun, 22 Jul 2007 10:50:04 -0700, Jim Papadopoulos
<jimpapadopoulos@gmail.com > wrote:
>On Jun 7, 2:32 pm, carlfo...@comcast.net wrote:
>> On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood
>>
>> <thomas.h...@gmail.com> wrote:
>> >http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/sci...
>>
>> SNIPSNIPSNIP
>>
>> A link to a video would be wonderful.
>>
>> Cheers,
>>
>> Carl Fogel
>
>The aforementioned Telegraph link has a video link at the top of the
>page. Do review it, to see a bicycle 'popping back up' after a shove.
>
>
>Also take a look at Arend Schwab's web page with treadmill
>experiments: http://audiophile.tam.cornell.edu/~als93/Bicycle/index.htm
>
>Arend was an important contributor to the discussed paper, and so am I
>
>Jim Papadopoulos
Dear Jim,
Thanks--here's the link, which is broken in some posts:
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
Here's the video at the top, with the sideways push in the second
half:
http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/wheel_bicycle_stability.mpg
It looks as if the initial push was indeed more powerful than my
childhood disasters. Probably it helps to be over three feet tall.
Cheers,
Carl Fogel
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Date: 07 Jun 2007 17:24:56
From: Gary Young
Subject: Re: The mathematical way to ride a bike
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On Thu, 07 Jun 2007 13:32:52 -0600, carlfogel wrote:
> On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood <thomas.hood@gmail.com>
> wrote:
>
>>http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>>
>>Paper here:
>>http://tinyurl.com/2ducg9
>>
>>Apologies if this is old news,
>>
>>Tom
>
> Dear Tom,
>
> This passage caused my eyebrows to rise:
>
> "Today's 'definitive review' underlines bicycles' amazing ability to
> balance themselves. 'You can give a bike a push and it will go 50 metres
> without falling. Even if it is knocked sideways, it will pop up again,'
> said Prof Ruina.
>
> http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>
>
I'm not sure if this is meant to be public, but there seems to be a draft
of the paper here:
http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/papers/
Jim Papadopoulos is one of the authors and has a discussion of bicycle
stability in Chapter 8 of Wilson's Bicycling Science.
Among other things, he says,
"To perform steady-state riderless experiments, it is essential to have
low-friction steering, a condition of initial alignment that allows the
bicycle to travel straight, and a design that affords intrinsic stability
at the test speed. It is then possible to engage in bicycling activities
similar to a game of catch (rolling the bicycle to a partner) or kite
flying (propelling and leaning the bicycle by pulling on an attached
string)."
> Maybe I'm wrong, but I take this to mean a normal bicycle with no rider
> on an ordinary level road.
>
> A) That sounds like some push.
My recollection is that if you release a bicycle at the top of a gentle
hill, it will stay upright for a surprising distance (though it's been
years since I've tried anything like that). I imagine it would take
more finesse to achieve the same result on level ground because, as you
say, it would require quite a push to keep the bike above the threshold
speed for any length of time and a poorly executed push might start the
bike out in an unstable position. Still, I don't see any reason why the
same effect couldn't be achieved on level ground.
What raised my eyebrow in the news story was the statement that, "Even if
[the bicycle] is knocked sideways, it will pop up again." But on further
thought that seems right too. An irate motorist once tried to push me off
my bike. (I had dared to rap on his window when he turned into my path; he
pulled ahead and darted out of his car at me as I passed.) It's possible
that I subconsciously took corrective action, but what struck me as it was
happening was how ineffectual the push was. There didn't seem to be any
force which needed my corrections. But perhaps I'm jumping to conclusions
in thinking that the bicycle (with me attached) was self-correcting.
> B) I seem to recall that the bike falls over pretty quickly.
>
> Anyone who can offer an explanation adapted to a particularly mean
> understanding, I'd appreciate it. Maybe the bicycles that I experimented
> with as a little boy were different.
>
> A link to a video would be wonderful.
>
> Cheers,
>
> Carl Fogel
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Date: 07 Jun 2007 17:11:33
From: Gary Young
Subject: Re: The mathematical way to ride a bike
|
On Thu, 07 Jun 2007 13:32:52 -0600, carlfogel wrote:
> On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood <thomas.hood@gmail.com>
> wrote:
>
>>http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>>
>>Paper here:
>>http://tinyurl.com/2ducg9
>>
>>Apologies if this is old news,
>>
>>Tom
>
> Dear Tom,
>
> This passage caused my eyebrows to rise:
>
> "Today's 'definitive review' underlines bicycles' amazing ability to
> balance themselves. 'You can give a bike a push and it will go 50 metres
> without falling. Even if it is knocked sideways, it will pop up again,'
> said Prof Ruina.
>
> http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>
>
>
I'm not sure if this is meant to be public, but there seems to be a draft
of the paper here:
http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/papers/
Jim Papadopoulos is one of the authors and has a discussion of bicycle
stability in Chapter 8 of Wilson's Bicycling Science.
Among other things, he says,
"To perform steady-state riderless experiments, it is essential to have
low-friction steering, a condition of initial alignment that allows the
bicycle to travel straight, and a design that affords intrinsic stability
at the test speed. It is then possible to engage in bicycling activities
similar to a game of catch (rolling the bicycle to a partner) or kite
flying (propelling and leaning the bicycle by pulling on an attached
string)."
> Maybe I'm wrong, but I take this to mean a normal bicycle with no rider
> on an ordinary level road.
>
> A) That sounds like some push.
My recollection is that if you release a bicycle at the top of a gentle
hill, it will stay upright for a surprising distance (though it's been
years since I've tried anything like that). I imagine it would take more
finesse to achieve the same result on level ground because, as you say, it
would require quite a push to keep the bike above the threshold speed for
any length of time and a poorly executed push might start the bike out in
an unstable position. Still, I don't see any reason why the same effect
couldn't be achieved on level ground.
What raised my eyebrow in the news story was the statement that, "Even if
[the bicycle] is knocked sideways, it will pop up again." But on further
thought that seems right too. An irate motorist once tried to push me off
my bike. (I had dared to rap on his window when he turned into my path; he
pulled ahead and darted out of his car at me as I passed.) It's possible
that I subconsciously took corrective action, but what struck me as it was
happening was how ineffectual the push was. There didn't seem to be any
force which needed my corrections. But perhaps I'm jumping to conclusions
in thinking that the bicycle (with me attached) was self-correcting.
> B) I seem to recall that the bike falls over pretty quickly.
>
> Anyone who can offer an explanation adapted to a particularly mean
> understanding, I'd appreciate it. Maybe the bicycles that I experimented
> with as a little boy were different.
>
> A link to a video would be wonderful.
>
> Cheers,
>
> Carl Fogel
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Date: 07 Jun 2007 13:32:52
From:
Subject: Re: The mathematical way to ride a bike
|
On Thu, 07 Jun 2007 03:35:54 -0700, Thomas Hood
<thomas.hood@gmail.com > wrote:
>http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>
>Paper here:
>http://tinyurl.com/2ducg9
>
>Apologies if this is old news,
>
>Tom
Dear Tom,
This passage caused my eyebrows to rise:
"Today's 'definitive review' underlines bicycles' amazing ability to
balance themselves. 'You can give a bike a push and it will go 50
metres without falling. Even if it is knocked sideways, it will pop up
again,' said Prof Ruina.
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
Maybe I'm wrong, but I take this to mean a normal bicycle with no
rider on an ordinary level road.
A) That sounds like some push.
B) I seem to recall that the bike falls over pretty quickly.
Anyone who can offer an explanation adapted to a particularly mean
understanding, I'd appreciate it. Maybe the bicycles that I
experimented with as a little boy were different.
A link to a video would be wonderful.
Cheers,
Carl Fogel
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Date: 07 Jun 2007 16:01:36
From: Bill
Subject: Re: The mathematical way to ride a bike
|
Thomas Hood wrote:
> http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/06/06/scibike06.xml
>
> Paper here:
> http://tinyurl.com/2ducg9
>
> Apologies if this is old news,
>
> Tom
>
Funny, really, since the control mechanism is the supercomputer between
the ears of the rider. In computer speak we could just say that the
brain is a heuristic learning computer. Fall down, analyze what was done
wrong and try again until able to maintain upright position.
Simple, huh?
Bill Baka
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