My Experiment...

On Feb 28, 2:36 am, Martin Dann <[email hidden]>

Quoted message said:

I think cats must do something similar with their legs, tail and
possibly head.

Yup and also use air drag, same as skydivers.

However, my partners neighbours cat manages to specialize in falling
on it's back. Because of the steepness of the road there is a
retaining wall stopping her garden sliding into next doors (probably
about 2 feet tall). The cat likes to walk along the edge of the wall
when getting from one end of the garden to the other.

One day my partner had the sprinkler going and the cat was trying to
time it so that it didn't get wet. Twice it got it wrong, got sprayed
with water and fell off the wall onto it's back. It was hilarious,
especially watching the cat pretend nothing had happened.

Quoted message said:

Of course the real question is how does toast always manage to land
butter side down, as it does not have limbs or intelligence :-)

Intelligent design ;-)

Because the EM force is so much stronger than the gravitational force
we have evolved to be the height we are (EM force giving strength to
chemical bonds in bones) and so have tables the height we do. Because
gravity is so weak something like toast sliding off a table gains just
enough rotation while it's part held up by the table and part falling
down that it does a half turn on it's way down.

Interesting PhD project for someone - vary the relative strengths of
EM and gravity, work out how tall "humans" would be and therefore how
tall their tables would be and so how universal a law "butter side
down" is across conceivable universes.

God was a practical joker!

Tim.

Martin Dann said:

Roger Thorpe said:

Fortunately nobody has mentioned the way dropped cats manage to turn
over in mid air.

Ooops (puts hand to mouth)

Imagine you are stood[1] in a space suit in space not rotating and not
attached to anything else, and you want to turn "upside down"[2]. If you
swing both arms in circles in the same direction parallel to your body,
you will rotate the other way as long as your arms are moving. Once you
stop swinging your arms, you body will stop rotating. [3]

I think cats must do something similar with their legs, tail and
possibly head.

Of course the real question is how does toast always manage to land
butter side down, as it does not have limbs or intelligence :-)

[1] or whatever the word is for zero gravity.
[2] ditto
[3] of course if this is your only method of turning, you are probably
dead, even if you try and pull a David Bowman[4]
[4] His h*lm*t saved his life because he took it off and threw it away :-)

Martin.

Oh blimey, you're right.
I had a much more complicated technique in mind. I was trying to be too
clever. I'm off lo look up 'hubris' in the dictionary.
Roger Thorpe

--
Roger Thorpe

My email address is spamtrapped. You can work it out!

In news:[email hidden],
Martin Dann <[email hidden]> tweaked the Babbage-Engine to
tell us:

Quoted message said:

I think cats must do something similar with their legs, tail and
possibly head.

Of course the real question is how does toast always manage to land
butter side down, as it does not have limbs or intelligence :-)

With all this global warming bobbins in the news, you'd think someone would
be doing some serious research into harnessing the power generation
possibilities of buttered cats...

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
If you are choking on an ice cube, simply pour a jug of boiling
water down your throat and presto! The blockage is almost
instantly removed.

Quoted post said:

Interesting PhD project for someone - vary the relative strengths of
EM and gravity, work out how tall "humans" would be and therefore how
tall their tables would be and so how universal a law "butter side
down" is across conceivable universes.

I read about a statistician who was surprised to notice that whenever
his little daughter dropped the toast it landed butter side up.
Initially he thought he was just lucky but it was happening so
consistently it couldn't be due to chance. It was only when he stopped
doing the mental arithmetic and decided to investigate further that he
discovered she was buttering her toast on both sides.

--
Dave...

Ben C said:

I don't understand Jobst Brandt's theory for why countersteer is
necessary, although he may be right. I don't see why you can't lean
the
bike over to initiate the turn just by shifting your centre of mass.

For the same reason you can't walk to the top of an unsupported ladder and
just balance on it. To balance on ladder you have to walk the bottom of it
underneath yourself.

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/

--
Posted via NewsDemon.com - Premium Uncensored Newsgroup Service
------->>>>>>http://www.NewsDemon.com<<<<<<------
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AndyMorris said:

Ben C said:

I don't understand Jobst Brandt's theory for why countersteer is
necessary, although he may be right. I don't see why you can't lean
the
bike over to initiate the turn just by shifting your centre of mass.

For the same reason you can't walk to the top of an unsupported ladder and
just balance on it. To balance on ladder you have to walk the bottom of it
underneath yourself.

Not true. Balancing on a ladder whose feet stay where they are is
possible, if difficult, and does not require any physical impossibility
like "pulling yourself up by your bootstraps".

Here is my earlier explanation (in this thread). Further down the thread
is a link to a video of a man balancing on a ladder.

http://groups.google.co.uk/group/uk.rec.cycling/msg/40e326853f0337c7?hl=en&

More interesting is the suggestion made that you'd somehow need a very
pronounced lean, bigger than what anyone ever does, in order to make a
turn. I'm still mulling over that one.

On 2007-03-01, [email hidden] <[email hidden]> wrote:
[...]

Quoted message said:

Yes, I agree that people who are not familiar with such elementary
concepts may not be able to understand the issues. Anyone who insists
that they can transport themselves sideways by dint of willpower
without there being any external force acting on them is not going to
be convinced by usenet debate

Was anyone insisting that?

Quoted message said:

, although they can still be pushed in the direction of learning about
it if they are prepared to try simple experiments (like riding a
bicycle with locked steering) that refute their beliefs.

How would that experiment be used to refute the believe that an object
can be moved sideways with willpower and no external force?

It seems a bad choice of experiment, as there are external forces
readily accessible to the rider in that system. How would you be sure
he wasn't cheating and using them instead of willpower?

Ben C said:

On 2007-03-01, [email hidden] <[email hidden]> wrote:
[...]

Quoted message said:

Yes, I agree that people who are not familiar with such elementary
concepts may not be able to understand the issues. Anyone who insists
that they can transport themselves sideways by dint of willpower
without there being any external force acting on them is not going to
be convinced by usenet debate

Was anyone insisting that?

I think you talked about "just shifting your centre of mass" just a
few posts ago.

Quoted message said:

Quoted message said:

, although they can still be pushed in the direction of learning about
it if they are prepared to try simple experiments (like riding a
bicycle with locked steering) that refute their beliefs.

How would that experiment be used to refute the believe that an object
can be moved sideways with willpower and no external force?

It seems a bad choice of experiment, as there are external forces
readily accessible to the rider in that system. How would you be sure
he wasn't cheating and using them instead of willpower?

Readily accessible? Why haven't you dared try it yet then?

For a less painful version, just sit on your bicycle, and as you
topple off to one side, "just shift your centre of mass" to the other
side (while keeping hold of the bars and your feet on the pedals as in
normal riding) so you dismount the other way. You don't need to bother
to lock the steering so long as you promise not to to turn the bars
sharply (which will shift the bike under you due to the fork
geometry).

Assuming you can "just shift your mass" enough to make an appreciable
impact in normal riding, you should be able to wait until you are a
significant way off-balance before tipping yourself back up, and it
won't require any extreme contortions.

Perhaps you could make a video and put it on youtube.

James

Quoted message said:

Assuming you can "just shift your mass" enough to make an appreciable
impact in normal riding, you should be able to wait until you are a
significant way off-balance before tipping yourself back up

Ride a normal bike, at 10-12mph or so, in a straight line. At no point are
you a significant way off-balance. The adjustments needed to keep balance
are very small - a matter of a few degrees turn of the wheel.

No, imagine that someone wishes to move the CofG of bike+rider relative to
the bike in order to initiate a turn. They can either countersteer, not
correct for something-or-other (road camber, wind, previous countersteer,
whatever) that has bike+rider shifting CofG in that direction anyway, or
they could shift it by moving themselves or the bike (but without turning
the wheels).

It is the last option that is under dispute. The CofG would need be moved
only a tiny amount before it became self-wossnaming, and the CofG moved far
enough to for the rider to turn the bars 'normally'[1] to carry out the
turn. Little control is needed - the rider merely has to do enough that it
goes one way and not the other.

The difficulty in measuring this is that countersteering is impossible not
to do unless you've nobbled the steering somehow (well, it's impossible for
me not to do).

So, to recap, the argument was whether it was possible to shift the CofG
far enough to turn, without the use of countersteer. My view is that it is,
but that we countersteer 'cos it's so much easier and pretty much
impossible not to (even if you do lean, you'll still be countersteering at
some point). However, shifting centre of gravity without countersteer?
Yeah, that can be done. <smiley> It's as easy as falling off </smiley>

[1] i.e. left to go left, right to go right.

On Mar 1, 8:53 pm, Mark Thompson

pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com said:

Quoted message said:

Assuming you can "just shift your mass" enough to make an appreciable
impact in normal riding, you should be able to wait until you are a
significant way off-balance before tipping yourself back up

Ride a normal bike, at 10-12mph or so, in a straight line. At no point are
you a significant way off-balance. The adjustments needed to keep balance
are very small - a matter of a few degrees turn of the wheel.

No, imagine that someone wishes to move the CofG of bike+rider relative to
the bike in order to initiate a turn. They can either countersteer, not
correct for something-or-other (road camber, wind, previous countersteer,
whatever) that has bike+rider shifting CofG in that direction anyway, or
they could shift it by moving themselves or the bike (but without turning
the wheels).

Now try doing it at 25mph and making a sharp turn. It's not that hard
to work out how long it takes for a rider who's CoG is (say) initially
1cm off-centre, to fall through a 30 degree angle. It would also be
painfully obvious if anyone actually bothered the trivial test of
riding through a puddle at a decent speed on a dry road, followed by
taking a corner. Simon's off-centre photos with fat tyres on a beach
were a bit unclear but gave a pretty strong hint.

Quoted message said:

So, to recap, the argument was whether it was possible to shift the CofG
far enough to turn, without the use of countersteer.

No, Simon's claim was not that this was a theoretical possibility in
extremis (which I have repeatedly acknowledged might be possible) but
that it is the normal mode of steering not just for him but for most
cyclists, which doesn't pass the laugh test.

James

Quoted message said:

that this was a theoretical possibility in
extremis (which I have repeatedly acknowledged might be possible)

Bugger, so we agree with everything the other is saying? (well, you say
'might', I say 'is'😉.

Quoted message said:

Ben C said:

On 2007-03-01, [email hidden] <[email hidden]> wrote:
[...]

Quoted message said:

Yes, I agree that people who are not familiar with such elementary
concepts may not be able to understand the issues. Anyone who insists
that they can transport themselves sideways by dint of willpower
without there being any external force acting on them is not going to
be convinced by usenet debate

Was anyone insisting that?

I think you talked about "just shifting your centre of mass" just a
few posts ago.

And I thought you conceded that balancing on a ladder or a bike with
locked steering was possible if difficult, or perhaps it was someone
else.

We're talking about shifting the centre of mass of bike+rider relative
to where the tyres touch the ground. The bike+rider COM does not move
relative to the NRF, initially, although it does as the bike starts to
tip and frictional forces at the contacts oppose the torque on it.

No psychokinesis required.

Quoted message said:

Quoted message said:

Quoted message said:

, although they can still be pushed in the direction of learning about
it if they are prepared to try simple experiments (like riding a
bicycle with locked steering) that refute their beliefs.

How would that experiment be used to refute the believe that an object
can be moved sideways with willpower and no external force?

It seems a bad choice of experiment, as there are external forces
readily accessible to the rider in that system. How would you be sure
he wasn't cheating and using them instead of willpower?

Readily accessible? Why haven't you dared try it yet then?

For a less painful version, just sit on your bicycle, and as you
topple off to one side, "just shift your centre of mass" to the other
side (while keeping hold of the bars and your feet on the pedals as in
normal riding) so you dismount the other way. You don't need to bother
to lock the steering so long as you promise not to to turn the bars
sharply (which will shift the bike under you due to the fork
geometry).

As I've said, I am no good at circus tricks. Balancing on a stationary
bicycle, especially one with locked steering, is not a skill required
for normal riding. But the fact that it is possible indicates that is
possible to initiate a turn by leaning. It does not follow however that
initiating a turn by leaning requires the skills of a circus clown.

Quoted message said:

Assuming you can "just shift your mass" enough to make an appreciable
impact in normal riding, you should be able to wait until you are a
significant way off-balance before tipping yourself back up

I don't see how that conclusion follows from the premise.

Ben C said:

Quoted message said:

Ben C said:

On 2007-03-01, [email hidden] <[email hidden]> wrote:
[...]

Quoted message said:

Quoted message said:

> Yes, I agree that people who are not familiar with such elementary
> concepts may not be able to understand the issues. Anyone who insists
> that they can transport themselves sideways by dint of willpower
> without there being any external force acting on them is not going to
> be convinced by usenet debate

Quoted message said:

Quoted message said:

Was anyone insisting that?

Quoted message said:

I think you talked about "just shifting your centre of mass" just a
few posts ago.

And I thought you conceded that balancing on a ladder or a bike with
locked steering was possible if difficult, or perhaps it was someone
else.

Yes, my point is it is not a trick i would hand-wave away with "just",
and I'm sure that the vast majority of people cannot balance in such a
way.

Quoted message said:

We're talking about shifting the centre of mass of bike+rider relative
to where the tyres touch the ground. The bike+rider COM does not move
relative to the NRF, initially,

So does it or doesn't it move? Is there a typo to explain the direct
contradiction in these two sentences?

Quoted message said:

Quoted message said:

Quoted message said:

It seems a bad choice of experiment, as there are external forces
readily accessible to the rider in that system. How would you be sure
he wasn't cheating and using them instead of willpower?

Quoted message said:

Readily accessible? Why haven't you dared try it yet then?

Quoted message said:

For a less painful version, just sit on your bicycle, and as you
topple off to one side, "just shift your centre of mass" to the other
side (while keeping hold of the bars and your feet on the pedals as in
normal riding) so you dismount the other way. You don't need to bother
to lock the steering so long as you promise not to to turn the bars
sharply (which will shift the bike under you due to the fork
geometry).

As I've said, I am no good at circus tricks.

But you just said that the external forces were "readily available".
How can they be both "readily available" and yet only accessible to
circus clowns?

To put the shoe on the other foot, since you are not prepared to try
the trivial experiments I have suggested (which certainly would show
that the possibility to "just shift your centre of mass sideways" is
extremely limited), can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

James

Quoted message said:

Ben C said:

Quoted message said:

On Mar 1, 5:44 pm, Ben C <[email hidden]> wrote:

[...]

Quoted message said:

Quoted message said:

We're talking about shifting the centre of mass of bike+rider relative
to where the tyres touch the ground. The bike+rider COM does not move
relative to the NRF, initially,

So does it or doesn't it move? Is there a typo to explain the direct
contradiction in these two sentences?

It's not a contradiction. If you're sitting in zero-gravity, you can
touch your toes. Your COM moves relative to your toes, but not relative
to the NRF.

A movement like that, not requiring any lateral forces from the NRF,
causes a torque to the bike+rider as soon as the weight becomes out of
line with the support points, making bike+rider begin to tip over.

As soon as it starts to tip, there is an external force at the contacts
which causes it to pivot around the contact rather than around its COM.
At this point the COM is moving relative to the NRF.

Quoted message said:

Quoted message said:

Quoted message said:

> It seems a bad choice of experiment, as there are external forces
> readily accessible to the rider in that system. How would you be sure
> he wasn't cheating and using them instead of willpower?

Quoted message said:

Readily accessible? Why haven't you dared try it yet then?

Quoted message said:

For a less painful version, just sit on your bicycle, and as you
topple off to one side, "just shift your centre of mass" to the other
side (while keeping hold of the bars and your feet on the pedals as in
normal riding) so you dismount the other way. You don't need to bother
to lock the steering so long as you promise not to to turn the bars
sharply (which will shift the bike under you due to the fork
geometry).

As I've said, I am no good at circus tricks.

But you just said that the external forces were "readily available".
How can they be both "readily available" and yet only accessible to
circus clowns?

Accessible to everyone, but it takes a clown to control them.

Quoted message said:

To put the shoe on the other foot, since you are not prepared to try
the trivial experiments I have suggested (which certainly would show
that the possibility to "just shift your centre of mass sideways" is
extremely limited), can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

As I said earlier, leaning into a corner does not require clown ability.
Clowns enter the discussion only to illuminate the descriptions of why
it is possible to lean over without needing psychokinesis. We use the
same physics as the clowns, but not the same skill. They use this effect
to balance on things, I'm only suggesting that cyclists may use it to
initiate turns.

Ben C said:

Quoted message said:

Ben C said:

On 2007-03-01, [email hidden] <[email hidden]> wrote:

Quoted message said:

Quoted message said:

> On Mar 1, 5:44 pm, Ben C <[email hidden]> wrote:

[...]

Quoted message said:

Quoted message said:

We're talking about shifting the centre of mass of bike+rider relative
to where the tyres touch the ground. The bike+rider COM does not move
relative to the NRF, initially,

Quoted message said:

So does it or doesn't it move? Is there a typo to explain the direct
contradiction in these two sentences?

It's not a contradiction. If you're sitting in zero-gravity, you can
touch your toes. Your COM moves relative to your toes, but not relative
to the NRF.

Yes, the toes can move relative to the NRF. Are you claiming that the
contact patch does? If so, how, other than by steering?

Quoted message said:

A movement like that, not requiring any lateral forces from the NRF,

What sort of (lateral) movement is it that requires no lateral force?

Quoted message said:

Quoted message said:

To put the shoe on the other foot, since you are not prepared to try
the trivial experiments I have suggested (which certainly would show
that the possibility to "just shift your centre of mass sideways" is
extremely limited), can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

As I said earlier, leaning into a corner does not require clown ability.
Clowns enter the discussion only to illuminate the descriptions of why
it is possible to lean over without needing psychokinesis. We use the
same physics as the clowns, but not the same skill. They use this effect
to balance on things, I'm only suggesting that cyclists may use it to
initiate turns.

To put the shoe on the other foot, since you are not prepared to try
the trivial experiments I have suggested (which certainly would show
that the possibility to "just shift your centre of mass sideways" is
extremely limited), can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

James

Quoted message said:

can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

Sit astride bike. Remove pressure from seat (i.e. take your weight on the
pedals) and tilt bike to the side. Then move body the same way. Centre of
gravity has moved so much that you fall off quite quickly.

On 2 Mar, 11:17, Mark Thompson

pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com said:

Quoted message said:

can you suggest any experiment which would
actually demonstrate the existence of such an ability at a level which
might make a perceptible difference in bicycle riding?

Sit astride bike. Remove pressure from seat (i.e. take your weight on the
pedals) and tilt bike to the side. Then move body the same way. Centre of
gravity has moved so much that you fall off quite quickly.

To make it meaningful the steering would have to be locked straight.
On such a bike it is virtually impossible to remain balanced long
enough to perform this experiment. You always tip one way or the other
because of the egg-balanced-on-the-little-end effect. It's obvious you
still haven't experimented with locking your bike's steering.

It also seems you don't have an appreciation of the laws of motion.
You seem to think the rider could move the bike without a reaction
moving his body the other way, and then somehow move his body towards
the bike without the reaction pulling the bike upright again.

Also note that in normal bike riding with hands on the bars the rider
does not tilt the bike and his body in opposite directions. A smooth
turn is made with the rider's body and the bike remaining in the same
plane.

--
Dave...

Quoted message said:

To make it meaningful the steering would have to be locked straight.

I've just nicked a mates unused heap of junk. What do I do to the headset
to lock the steering? I think it's a threaded headset, and I have a
headset spannery-thing.

Quoted message said:

Also note that in normal bike riding with hands on the bars the rider
does not tilt the bike and his body in opposite directions. A smooth
turn is made with the rider's body and the bike remaining in the same
plane.

I've already said that in normal riding we use countersteer to move the
centre of gravity. I merely think that it's possible to move the CofG
without having to resort to countersteer.

On Mar 2, 12:40 pm, Mark Thompson

pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com said:

Quoted message said:

To make it meaningful the steering would have to be locked straight.

I've just nicked a mates unused heap of junk. What do I do to the headset
to lock the steering? I think it's a threaded headset, and I have a
headset spannery-thing.

Quoted message said:

Also note that in normal bike riding with hands on the bars the rider
does not tilt the bike and his body in opposite directions. A smooth
turn is made with the rider's body and the bike remaining in the same
plane.

I've already said that in normal riding we use countersteer to move the
centre of gravity. I merely think that it's possible to move the CofG
without having to resort to countersteer.

Disregarding air resistance there is only the friction against the
ground that can move the CoG

So if you lean the bike to the left the COG will (slightly) move to
the right. Leaning the bike to the left will also move the contact
patch to the left.

The net effect being that if you lean the bike to the left you will
fall off to the right assuming you started balanced.

Tim.

On 2 Mar, 12:40, Mark Thompson

pleasegivegenerously@warmmail*_turn_up_the_heat_to_reply*.com said:

Quoted message said:

To make it meaningful the steering would have to be locked straight.

I've just nicked a mates unused heap of junk. What do I do to the headset
to lock the steering? I think it's a threaded headset, and I have a
headset spannery-thing.

Use a thin headset spanner to hold the threaded race (immediately
below the locknut) and loosen the locknut. Tighten the threaded race
until the steering is solid then tighten the locknut down onto it
without backing off the threaded race.

The locknut may be very hard to start moving so be careful not to
injure yourself if it moves suddenly or if the spanner slips. Ideally
you should use a thicker spanner for the locknut. Once you've locked
the steering take care on the bike as it will be impossible to
ride. :-)

Have fun!

--
Dave...