Optical illusions, continued ...

In article <[email hidden]>,

Sandy said:

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Quoted message said:

For us engineering-impaired,
I offer :
"Triangle is a convex polygon with three segments joining three
non-collinear points. Each of the three segments is called a side,
and each of the three non-collinear points is called a vertex"

For a physical structure, if the "segment" can transmit force from one
vertex to the other without deforming, then that is as good as a
straight line, from a performance point of view. Wouldn't you agree?

You can win any circular argument, of course you're right. I suspect,
though, that the issue is right there - is there deformation or not. From
the absolute of no deformation to the cooked spaghetti version, it seems
that some manufacturers claim that they construct some sort of controlled
deformation in their frames. After all, there is clear flex in a lateral
plane. The comment has been repeated, often, that a seatstay that
vertically flexes won't do it very long before failure. Yet at the same
attachment point, it is know to flex laterally. I don't know, but I can
recognize a logical gap, even without a micrometer.

Quoted message said:

So you could form a functional tetrahedron from straight tubing or
bent ones as long as the physical capacity of the tubes is not
exceeded. It might not be what Euclid had in mind but he'd probably
appreciate the application.

No argument on this model - to posit it doesn't flex and take that to mean
that you just proved it doesn't flex doesn't move this idea anywhere,
really.

Were the struts or joints in the rear tetrahedron to
deform on a macroscopic scale the alignment of the drive
train would change, affecting energy transmission,
inducing auto shifts, and drawing energy out of the system
into flexing the structural elements. Hence there is no
macroscopic flex.

--
Michael Press

Dans le message de
news:[email hidden],
Michael Press <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

In article <[email hidden]>,

Sandy said:

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a
déclaré :

Quoted message said:

> For us engineering-impaired,
> I offer :
> "Triangle is a convex polygon with three segments joining three
> non-collinear points. Each of the three segments is called a side,
> and each of the three non-collinear points is called a vertex"

For a physical structure, if the "segment" can transmit force from
one vertex to the other without deforming, then that is as good as a
straight line, from a performance point of view. Wouldn't you
agree?

You can win any circular argument, of course you're right. I
suspect, though, that the issue is right there - is there
deformation or not. From the absolute of no deformation to the
cooked spaghetti version, it seems that some manufacturers claim
that they construct some sort of controlled deformation in their
frames. After all, there is clear flex in a lateral plane. The
comment has been repeated, often, that a seatstay that vertically
flexes won't do it very long before failure. Yet at the same
attachment point, it is know to flex laterally. I don't know, but I
can recognize a logical gap, even without a micrometer.

Quoted message said:

So you could form a functional tetrahedron from straight tubing or
bent ones as long as the physical capacity of the tubes is not
exceeded. It might not be what Euclid had in mind but he'd probably
appreciate the application.

No argument on this model - to posit it doesn't flex and take that
to mean that you just proved it doesn't flex doesn't move this idea
anywhere, really.

Were the struts or joints in the rear tetrahedron to
deform on a macroscopic scale the alignment of the drive
train would change, affecting energy transmission,
inducing auto shifts, and drawing energy out of the system
into flexing the structural elements. Hence there is no
macroscopic flex.

.... another circle

Sandy said:

Dans le message de
news:[email hidden],
Michael Press <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Were the struts or joints in the rear tetrahedron to
deform on a macroscopic scale the alignment of the drive
train would change, affecting energy transmission,
inducing auto shifts, and drawing energy out of the system
into flexing the structural elements. Hence there is no
macroscopic flex.

... another circle

Not at all. Michael described symptoms that would exist if there were
enough flex to matter. That they don't exist is evidence that there
isn't enough flex to matter. You may disagree with certain aspects of
his logic, but it's certainly not circular.

BTW, I recall a conversation with a friend telling of his college
experience with law students. As he said, "Those guys will argue
_anything_. We'd be in the cafeteria getting our seats, and the law
students would be debating each other about who should get which seat."

Sandy, perhaps you should treat this as a legal case. Perhaps you
should hire an expert witness with proper technical knowledge and
credentials.

Then just sit down. ;-)

- Frank Krygowski

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Sandy said:

Dans le message de
news:[email hidden],
Michael Press <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Were the struts or joints in the rear tetrahedron to
deform on a macroscopic scale the alignment of the drive
train would change, affecting energy transmission,
inducing auto shifts, and drawing energy out of the system
into flexing the structural elements. Hence there is no
macroscopic flex.

... another circle

Not at all. Michael described symptoms that would exist if there were
enough flex to matter. That they don't exist is evidence that there
isn't enough flex to matter. You may disagree with certain aspects of
his logic, but it's certainly not circular.

Well, it _is_ circular, if it begins with a presumption that the measurement
is "macroscopic" and thus concludes that it is "macroscopic". Like your
"negligible", it fails to address measurements.

Would a deflection of 0.1mm be *micro*scopic or *macro*scopic ? What about
0.5mm or 2mm or 5mm ? Those are all testing data for a variety of frames'
rear triangle flex.

Just the mention of "autoshifting" leads inexorably to the conclusion (which
most of us know to be completely factual) that there are frames which behave
exactly that way. And leads to the conclusion that Mr Press knew that when
he wrote it.
--
Sandy

The above is guaranteed 100% free of sarcasm,
denigration, snotty remarks, indifference, platitudes, fuming demands that
"you do the math", conceited visions of a better world on wheels according
to [insert NAME here].

Sandy said:

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Sandy said:

Dans le message de
news:[email hidden],
Michael Press <[email hidden]> a réfléchi, et puis a déclaré :
>
> Were the struts or joints in the rear tetrahedron to
> deform on a macroscopic scale the alignment of the drive
> train would change, affecting energy transmission,
> inducing auto shifts, and drawing energy out of the system
> into flexing the structural elements. Hence there is no
> macroscopic flex.

... another circle

Not at all. Michael described symptoms that would exist if there were
enough flex to matter. That they don't exist is evidence that there
isn't enough flex to matter. You may disagree with certain aspects of
his logic, but it's certainly not circular.

Well, it _is_ circular, if it begins with a presumption that the measurement
is "macroscopic" and thus concludes that it is "macroscopic". Like your
"negligible", it fails to address measurements.

Would a deflection of 0.1mm be *micro*scopic or *macro*scopic ? What about
0.5mm or 2mm or 5mm ? Those are all testing data for a variety of frames'
rear triangle flex.

Just the mention of "autoshifting" leads inexorably to the conclusion (which
most of us know to be completely factual) that there are frames which behave
exactly that way. And leads to the conclusion that Mr Press knew that when
he wrote it.
--
Sandy

Lunch time is almost over, students.

Next period, law students will be heading to Debating class.
Engineering students will be heading for Vibrations laboratory. Each
group will, I'm sure, learn something valuable in their field.

Again, lunch time is almost over. Now, will the law students _please_
stop bickering and sit down?

- Frank Krygowski

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a déclaré :

Quoted message said:

Sandy said:

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et puis a
déclaré :

Quoted message said:

Sandy wrote:
> Dans le message de
> news:[email hidden],
> Michael Press <[email hidden]> a réfléchi, et puis a déclaré :
>>
>> Were the struts or joints in the rear tetrahedron to
>> deform on a macroscopic scale the alignment of the drive
>> train would change, affecting energy transmission,
>> inducing auto shifts, and drawing energy out of the system
>> into flexing the structural elements. Hence there is no
>> macroscopic flex.
>
> ... another circle

Not at all. Michael described symptoms that would exist if there
were enough flex to matter. That they don't exist is evidence that
there isn't enough flex to matter. You may disagree with certain
aspects of his logic, but it's certainly not circular.

Well, it _is_ circular, if it begins with a presumption that the
measurement is "macroscopic" and thus concludes that it is
"macroscopic". Like your "negligible", it fails to address
measurements.

Would a deflection of 0.1mm be *micro*scopic or *macro*scopic ?
What about
0.5mm or 2mm or 5mm ? Those are all testing data for a variety of
frames' rear triangle flex.

Just the mention of "autoshifting" leads inexorably to the
conclusion (which most of us know to be completely factual) that
there are frames which behave exactly that way. And leads to the
conclusion that Mr Press knew that when he wrote it.
--
Sandy

Lunch time is almost over, students.

Next period, law students will be heading to Debating class.
Engineering students will be heading for Vibrations laboratory. Each
group will, I'm sure, learn something valuable in their field.

Again, lunch time is almost over. Now, will the law students _please_
stop bickering and sit down?

- Frank Krygowski

It was a tough decision, really, but I feel much better no longer needing to
see your postings.

Sandy said:

It was a tough decision, really, but I feel much better no longer needing to
see your postings.

We have a president with the same mindset. That is, he only wants to
hear from people who already agree with him. It makes "thinking" a
much simpler exercise.

Ah well. Enough about politics!

- Frank Krygowski