Re: Carbon Fiber Seat Stays = Better Ride?

[[email protected]]

Sandy wrote:
> Dans le message de
> news:[email protected],
> [email protected] <[email protected]> a réfléchi, et puis a
déclaré :
>
> > The last time you posted measurements, you gave data on _lateral_
> > deflection, not vertical deflection. This was patiently explained
to
> > you.
>
> So ? Your condescension is noted, with a wry smile, sonny.

I haven't been called "sonny" for many, many years. Interesting
experience!

Regarding condescension - I can tell this dialog is decaying into that,
as evidenced by your statement to dvt: "Golly, you have a strange way
of using a keyboard to say nothing."

But to let you know: Scientists, engineers and mathematicians can
sometimes lose patience with people who are confident that their own
lack of education is immaterial. Despite that, I'll try to be patient.

But misplaced.
> You are happy to accept that there is damping in lateral deflection
and not
> vertical ? Interesting. Amplitude, frequency, decay ? Rationale ?

Perhaps the problem is "ride" is poorly defined. Perhaps you are
speaking of a different aspect of "ride" than most of us are.
Personally, what I've been discussing is road vibration and road shock.
Those phenomena occur almost entirely in the vertical plane.

And yes, I do understand that amplitude, frequency and decay can be
completely different in different directions. If you don't understand
that, it's further evidence that you're not equipped to contribute
meaningfully to this discussion.

Grab a flat ruler or meter stick. Clamp it horizontally to a table,
letting its length protrude. Vibrate it vertically. Vibrate it
horizontally, if you can. You'll see that behavior can be completely
different in different directions.


> If you believe that lateral deflection bears not at all on ride
quality,
> please let the rest of the world know.

The effect of lateral deflection on _vertical_ ride quality - that is,
shock and vibration absorption - is negligible.

If you believe that all bicycles are
> subject only to perfect vertical deflection for all the time they are

> ridden, also please let us know.

No, I've never said that. In fact, I've described lateral deflection
in an Alan aluminum frame I rode. However, it's not pertinent to the
problem at hand, which is vertical.


If you submit that there is *no*
> deflection in the vertical plane, for any and all types of materials
used to
> construct modern bicycles, please state that clearly.

Such a man of absolutes! I submit there is _negligible_ vertical
deflection in the seatstays of a conventional bike, no matter what the
material is. And I'm quite capable of calculating such deflections.
For that matter, so are most of the students in our freshman-level
courses.


> The problem you face is that we folks who ride and do experience
differences
> in bicycles

?? As if the rest of us don't ride bicycles??

are capable of measuring (sensing, with appropriate receptors
> all over the place) a good number of things that your crowd simply
has not
> yet figured out how to quantify to make you comprehend.

Ah yes. And the proof will come in the reports of blind tests
that you will very soon provide. Correct? ;-)

Your faith is charming, but not convincing. Let's have those blind
test reports.

- Frank Krygowski

 

[Sandy]

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

> Regarding condescension - I can tell this dialog is decaying into
> that, as evidenced by your statement to dvt: "Golly, you have a
> strange way of using a keyboard to say nothing."

Read what was targeted, and you _should_ see the relevance. Has to do with
measurements, Mr. Engineer.

> But to let you know: Scientists, engineers and mathematicians can
> sometimes lose patience with people who are confident that their own
> lack of education is immaterial. Despite that, I'll try to be
> patient.

Your condescension is noted, with a wry smile, sonny. (Sorry to repeat
myself, little one.)

>> You are happy to accept that there is damping in lateral deflection
>> and not vertical ? Interesting. Amplitude, frequency, decay ?
>> Rationale ?
>
> Perhaps the problem is "ride" is poorly defined.

Mr Engineer needs writing assistance.

> Perhaps you are
> speaking of a different aspect of "ride" than most of us are.

Not in the least ! But I am paying attention to more than the isolated
issue you wish to beat to death. I really would like to know what you ride,
why you chose that, and what it's ride quality is.

> Personally, what I've been discussing is road vibration and road
> shock. Those phenomena occur almost entirely in the vertical plane.

I see - you don't ride.

> And yes, I do understand that amplitude, frequency and decay can be
> completely different in different directions. If you don't understand
> that, it's further evidence that you're not equipped to contribute
> meaningfully to this discussion.

Asking can be a contribution. Well, I asked, as you were not observing any
other aspect of "ride quality". I had to ask, to understand if you have
been on two wheels recently.

> Grab a flat ruler or meter stick. Clamp it horizontally to a table,
> letting its length protrude. Vibrate it vertically. Vibrate it
> horizontally, if you can. You'll see that behavior can be completely
> different in different directions.

What I may want to do with a ruler is my business. And I behave.

>> If you believe that lateral deflection bears not at all on ride
>> quality, please let the rest of the world know.
>
> The effect of lateral deflection on _vertical_ ride quality - that is,
> shock and vibration absorption - is negligible.

We are limited to being vertical all the time ? You sure about that ? You
ride curves that way ? Over 5 km/h ?

>> If you believe that all bicycles are
>> subject only to perfect vertical deflection for all the time they are
>> ridden, also please let us know.
>
> No, I've never said that. In fact, I've described lateral deflection
> in an Alan aluminum frame I rode. However, it's not pertinent to the
> problem at hand, which is vertical.

Chainstays or seatstays, or the uniforked versions of them, don't move ?
Have you thought about the torsion at the attachment point, where the
lateral flex occurs ? Is there no contribution to a vertical change ? Or
is it lateral like a fully compliant hinge ? And the seatstays ? the
bottom bracket. Is the answer that all that other stuff is "negligible"?

>> If you submit that there is *no*
>> deflection in the vertical plane, for any and all types of materials
>> used to construct modern bicycles, please state that clearly.
>
> Such a man of absolutes! I submit there is _negligible_ vertical
> deflection in the seatstays of a conventional bike, no matter what the
> material is. And I'm quite capable of calculating such deflections.
> For that matter, so are most of the students in our freshman-level
> courses.

We are talking about people measuring what they sense. When you hit a bump,
do you take out your (noted above) ruler first, to confirm that the
topography you just traversed has adequate variability to be categorized as
a bump, or are you happy with the "seat of the pants" (Oh, how much fun that
was !) recognition of the fact ?

>> The problem you face is that we folks who ride and do experience
>> differences in bicycles
>
> ?? As if the rest of us don't ride bicycles??

I am not really convinced that _you_ do.

>>are capable of measuring (sensing, with appropriate receptors
>> all over the place) a good number of things that your crowd simply
>> has not yet figured out how to quantify to make you comprehend.

> Ah yes. And the proof will come in the reports of blind tests
> that you will very soon provide. Correct? ;-)

Blind proves nothing, just as you attempt to state that negligible yet
measurable differences are phantom ones. Measurable and sensible. The
issue brought up, at the origin of this thread, was whether there are actual
differences in ride quality, and whether they are significant enough to
consider alternative rear triangle composition in the purchase of a bike.
Perhaps you forgot. Not just are they measureable (which I'll bet you will
give me). The opinion (not engineering fact) about the value of the
measurable difference is what was sought. It's fine if you want to say that
you think the measureable differences are not worth spending money, but to
effectively say that the materials exhibit no differences is the extreme
position I fairly criticize.

Please take you time to make me look like a buffoon, as I have tired of this
and plan to be out, riding, early. I won't say I'll miss our
counterpoint....

 

[Scott]

Does anyone else recall the spate of 'blind' frame tests that were all
the rage when Columbus and others started coming out with a wide
variety of steel tubesets?

I recall one particular test back in the mid 90's where a bike mag
commissioned Marinoni to build 6 identical bikes, one from each of the
Columbus tubesets available at the time. They were indistinguishable,
except for the one made from the Max tubeset.

A group of testers took turns riding each one, over and over, recording
their observations. Before the test, each tester just KNEW they'd be
able to distinguish the frames built from the better tubesets, and
those built from the cheaper ones.

Funny thing happened at the end. While they couldn't really
distinguish one tubeset from the other, and didn't necessarily agree on
the various ride qualities they thought they observed, they unanimously
agreed on their favorite all around pick for a best frameset.

Turns out it was made from the Thron tubeset, which at the time was the
least expensive, least 'exotic' tubeset used in the frames tested.

If you really want to spend a lot of money on carbon stays, go ahead.
It's your money. Or, you could get some 'carbon'-looking tape to wrap
around your existing bike's stays, and it'll ride just as nicely as the
new one would.

 

[[email protected]]

Scott wrote:
> Does anyone else recall the spate of 'blind' frame tests that were
all
> the rage when Columbus and others started coming out with a wide
> variety of steel tubesets?
>
> I recall one particular test back in the mid 90's where a bike mag
> commissioned Marinoni to build 6 identical bikes, one from each of
the
> Columbus tubesets available at the time. They were
indistinguishable,
> except for the one made from the Max tubeset.
>
> A group of testers took turns riding each one, over and over,
recording
> their observations. Before the test, each tester just KNEW they'd be
> able to distinguish the frames built from the better tubesets, and
> those built from the cheaper ones.
>
> Funny thing happened at the end. While they couldn't really
> distinguish one tubeset from the other, and didn't necessarily agree
on
> the various ride qualities they thought they observed, they
unanimously
> agreed on their favorite all around pick for a best frameset.
>
> Turns out it was made from the Thron tubeset, which at the time was
the
> least expensive, least 'exotic' tubeset used in the frames tested.

That's the one blind road test I recall. I don't seem to have the
article on file, though.

>
> If you really want to spend a lot of money on carbon stays, go ahead.
> It's your money. Or, you could get some 'carbon'-looking tape to
wrap
> around your existing bike's stays, and it'll ride just as nicely as
the
> new one would.

I like the idea of carbon-look tape!

In fact, one could perform some interesting acts of charity with such
stuff. I'm sure we could sneak strips of it onto the seatstays of at
least a couple posters. Once they discovered the tape, they'd
doubtlessly notice an improvement in ride! What could be more kind?
;-)

- Frank Krygowski

 

[Benjamin Lewis]

Just zis Guy wrote:

> On Fri, 22 Apr 2005 08:40:29 -0500, James Spencer
> <[email protected]> wrote:
>
>> This conversation has really gotten absurd on all sides. Certainly the
>> idea that an inflated tire acts to insulate the rider from road
>> vibration is nonsense
>
> LOL! Why do you suppose the pneumatic tyre was invented in the first
> place?

I'm afraid you're only allowed to argue extremes here, Guy. If you're
claiming that a tire insulates the rider from vibration, you must claim
that it insulates from *all* vibration. Oh yeah, and you must also argue
that the vibration absorption of the frame is *exactly* zero, not merely
that it's small enough to be irrelevant.

--
Benjamin Lewis

Evelyn the dog, having undergone further modification, pondered the
significance of short-person behavior in pedal-depressed panchromatic
resonance and other highly ambient domains... "Arf", she said.

 

[Mark Hickey]

David Damerell <[email protected]> wrote:

>Quoting James Spencer <[email protected]>:
>>This conversation has really gotten absurd on all sides. Certainly the idea
>>that an inflated tire acts to insulate the rider from road vibration is
>>nonsense
>
>Is it? Try a "bone shaker" ride on bare rims some time.

Dang - beat me to it. I suspect that test WOULD change his mind, as
soon as it stopped vibrating.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Mark Hickey]

pinnah <[email protected]> wrote:

>[email protected] wrote:
>>The _one_ exception, where a magazine did set up a blind test, showed
>>the expert riders were absolutely incapable of detecting the touted
>>"differences."
>
>Do you have a referance for this article? I would love to see this.

It was in a mid 80's copy of 'Bicycle Guide', and was a revelation to
a lot of folks. Others popped another placebo in their mouth and
tossed it.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Benjamin Lewis]

Sandy wrote:

>> The effect of lateral deflection on _vertical_ ride quality - that is,
>> shock and vibration absorption - is negligible.
>
> We are limited to being vertical all the time ? You sure about that ?
> You ride curves that way ? Over 5 km/h ?

Vertical from the frame of reference of the bicycle, not gravity -- i.e. in
the same frame of reference that the deflection of the bicycle frame was
measured in. To put it another way, the bicycle does not actually have to
be upright in order to measure "vertical deflection" of the frame.

--
Benjamin Lewis

Evelyn the dog, having undergone further modification, pondered the
significance of short-person behavior in pedal-depressed panchromatic
resonance and other highly ambient domains... "Arf", she said.

 

[Mark Hickey]

[email protected] wrote:

Frank, never try to teach a pig to sing. It wastes your time and
annoys the pig.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[pinnah]

Mark Hickey <[email protected]> wrote:
>It was in a mid 80's copy of 'Bicycle Guide', and was a revelation to
>a lot of folks. Others popped another placebo in their mouth and
>tossed it.

So, this blind test compared a variety of steel tubesets against,
lessee, other steel tubesets. How is that supposed to shed light on
the differences of frames of different materials.?

Thanks for the ref though. Would love to find it.

 

[Mike Latondresse]

Mark Hickey <[email protected]> wrote in
news:[email protected]:

> pinnah <[email protected]> wrote:
>
>>[email protected] wrote:
>>>The _one_ exception, where a magazine did set up a blind test,
>>>showed the expert riders were absolutely incapable of detecting
>>>the touted "differences."
>>
>>Do you have a referance for this article? I would love to see
>>this.
>
> It was in a mid 80's copy of 'Bicycle Guide', and was a revelation
> to a lot of folks. Others popped another placebo in their mouth
> and tossed it.
>
> Mark Hickey
> Habanero Cycles
> http://www.habcycles.com
> Home of the $695 ti frame
>
>
Bicycle Guide was in my opinion the best magazine of its time and I
remember that article. All the bikes were painted red and the one that
was judged the best, if my memory serves me was made from the Aelle
tube set which was a welded tube, so way down the scale. What made me
happy was that I had just bought my a Cramerotti made with Aelle.

 

[[email protected]]

pinnah wrote:
>
> So, this blind test compared a variety of steel tubesets against,
> lessee, other steel tubesets. How is that supposed to shed light on
> the differences of frames of different materials.?

The reason we're mentioning that test is this: The magazine road
testers have _always_ authoritatively talked about ride quality,
including the smoothness of a bike's ride.

That magazine set up a blind test which proved their testers were
blowing smoke. They could _not_ detect what they claimed. That blind
test proved that the engineering calculations and measurements (showing
negligible differences) were correct. And thus, it proved the presence
of a strong placebo effect in evaluating frames.

The placebo effect remains. The engineering calculations and
measurements are the same as before. The claims from the road testers
are the same as before. The only difference is, before it was about
different types of steel. Now it's about steel and other materials.

- Frank Krygowski

 

[[email protected]]

On 23 Apr 2005 12:08:32 -0700, [email protected] wrote:

>
>pinnah wrote:
>>
>> So, this blind test compared a variety of steel tubesets against,
>> lessee, other steel tubesets. How is that supposed to shed light on
>> the differences of frames of different materials.?
>
>The reason we're mentioning that test is this: The magazine road
>testers have _always_ authoritatively talked about ride quality,
>including the smoothness of a bike's ride.
>
>That magazine set up a blind test which proved their testers were
>blowing smoke. They could _not_ detect what they claimed. That blind
>test proved that the engineering calculations and measurements (showing
>negligible differences) were correct. And thus, it proved the presence
>of a strong placebo effect in evaluating frames.
>
>The placebo effect remains. The engineering calculations and
>measurements are the same as before. The claims from the road testers
>are the same as before. The only difference is, before it was about
>different types of steel. Now it's about steel and other materials.
>
>- Frank Krygowski

Dear Frank,

Does your logic work if applied to tennis rackets that hit
squashy tennis balls with springy strings and are made of
wood, metal, and carbon fiber?

That is, are the tennis players feeling only a placebo
effect when they believe that shock and vibration are
reduced by the use of different materials?

Carl Fogel

 

[jim beam]

dvt wrote:
> jim beam wrote:
>
>> my point is that the
>> theory that a tire completely insulates the rider from any & all
>> perception of road surface is "incomplete". the balloon test
>> demonstrates that.
>
>
> Noone is claiming that "a tire completely insulates the rider from any &
> all perception of road surface." I'm not sure where you got that.
>
> The claim is this: The tire insulates the rider from perception of road
> surface *far more* than steel/aluminum/carbon fiber rear triangle.
> Differences in the stiff components are claimed to be a drop in the
> proverbial bucket.
>
thank you - very nicely put. i don't agree with that, but you sum the
argument up perfectly. it's just like the "aero spokes make no
difference" argument. truth is, there is a measurable difference. it
may be comparatively small hence the "a drop in the bucket" argument,
but if a single percent is what it takes to differentiate between 1st &
2nd, then bladed spokes /do/ matter. it's all about the win, right?
when was the last time you saw F1 won by a 5% or 10% time margin? how
about the tour? even a 0.05% margin is worth it.

returning to frame materials, composites /do/ measurably reduce
transmission of road vibration. that's fact. amazingly, actual testing
has even been cited in this thread [shock, horror]. but the argument
remains whether it's "significant". just because some "won't try, won't
test, won't listen" retrogrouch doesn't want to get off their dime and
starts getting all ****-of-the-walk when they confuse silence with
concession just because everyone else is simply bored into silence [or
in my case, has been stuck without n.g. access this last couple of days]
doesn't mean they know what they're talking about, far less that they've
bothered to try any of this equipment.

first time i read the r.b.t. grouches bleating these same old arguments
about carbon seat posts, my reaction was to actually buy one & try it.
i was pleasantly surprised to learn that it /did/ take some of the sting
out of the road. pre-ride, my expectation, based on the extreme
pseudo-tech convictions i'd read, was that there would be nothing. but
that was /way/ wrong. next, i tried carbon forks. even better - no
hand numbness on long rides. conclusion; beware the retro-grouches. in
reality, there's actually a strong trend suggesting the /opposite/ of
these strong convictions if history on carbon composite componentry,
brinelled headsets, metal fatigue, residual stress, rim anodizing,
lateral stability, elasto-hydrodynamic separation, etc. etc. are
anything to go by.

 

[[email protected]]

jim beam wrote:
> ... you sum the
> argument up perfectly. it's just like the "aero spokes make no
> difference" argument. truth is, there is a measurable difference.
it
> may be comparatively small hence the "a drop in the bucket" argument,

> but if a single percent is what it takes to differentiate between 1st
&
> 2nd, then bladed spokes /do/ matter. it's all about the win, right?
> when was the last time you saw F1 won by a 5% or 10% time margin?
how
> about the tour? even a 0.05% margin is worth it.

So in the "Tour de Comfort" a 0.05% reduction in road vibration
transmitted to your butt will "win"?

Maybe if a person rides exactly 30 miles before saying "Wow, those
annoying sonic-frequency buzzes transmitted through the seat stays are
NOW beginning to bother my super-sensitive butt," they may be able to
ride an extra 80 feet before making that same statement. Whew! Who
wouldn't pay a premium for _that_? ;-)


> returning to frame materials, composites /do/ measurably reduce
> transmission of road vibration. that's fact.

In your humble opinion?


amazingly, actual testing
> has even been cited in this thread [shock, horror].

Hmm. I recall one unreadable graph posted without explanation of how
it was generated, and available only hidden deeply in a company's
advertising literature.

Here's what "actual testing" should look like for this issue: You'll
need an accelerometer measuring vertical acceleration of the top part
of the bike saddle, when a rider is sitting on the saddle and the bike
is being ridden on an appropriate road surface.

This is not cheap, but it's not really rocket science. If a company
the size of Trek really had something to show, I think they could have
used this method to show it within two weeks or less.

> first time i read the r.b.t. grouches bleating these same old
arguments
> about carbon seat posts, my reaction was to actually buy one & try
it.
> i was pleasantly surprised to learn that it /did/ take some of the
sting
> out of the road. pre-ride, my expectation, based on the extreme
> pseudo-tech convictions i'd read, was that there would be nothing.
but
> that was /way/ wrong. next, i tried carbon forks. even better - no
> hand numbness on long rides. conclusion; beware the retro-grouches.

Alternate conclusion: Beware the placebo effect. It's powerful.

You know, if you've got the equipment, you _could_ set up a blind test.
(Actually, better do it double-blind, since you're clearly not neutral
on this issue.) Can you get some truly neutral riders, use the same
bike while changing the seatpost and hiding the seatpost from the
riders, and record their blind impressions? It might make an
interesting article.

Although, FWIW, I'm not as skeptical of CF seatposts and front forks as
I am of CF seat stays. The difference is, I think a competent engineer
could design a CF fork or a seatpost that had significant deflection to
absorb vibration.

But to design a seatstay that magically removes vibration despite being
rigid would be akin to magic.

And while there are plenty of people who believe strongly in certain
kinds of magic, it tends to go away when you hook an accelerometer to
it.

- Frank Krygowski

 

[[email protected]]

[email protected] wrote:
> On 23 Apr 2005 12:08:32 -0700, [email protected] wrote:
>
> >
> >That magazine set up a blind test which proved their testers were
> >blowing smoke. They could _not_ detect what they claimed. That
blind
> >test proved that the engineering calculations and measurements
(showing
> >negligible differences) were correct. And thus, it proved the
presence
> >of a strong placebo effect in evaluating frames.
> >
> >The placebo effect remains. The engineering calculations and
> >measurements are the same as before. The claims from the road
testers
> >are the same as before. The only difference is, before it was about
> >different types of steel. Now it's about steel and other materials.
> >
>
> Dear Frank,
>
> Does your logic work if applied to tennis rackets that hit
> squashy tennis balls with springy strings and are made of
> wood, metal, and carbon fiber?
>
> That is, are the tennis players feeling only a placebo
> effect when they believe that shock and vibration are
> reduced by the use of different materials?

I'm much less familiar with tennis than I am with cycling. I don't
know what the claims are for CF tennis rackets, and I don't even know
what the alternative materials are these days. (The only tennis racket
I've ever owned was wood, and it was tossed when it warped.) Also, I
note the impact of a racket and ball is _much_ different than the
vibrations transmitted from the road to a cyclist's butt.

But it seems to me the question is this: Have the tennis rackets been
tested in a blind test? If the players can sense less shock and
vibration when they don't know what the racket material is, that might
tell us something.

It would be a bit tricky. For one thing, unlike in a bike frame, the
mass and moment of inertia of the racket are easily perceptible to the
player. The sound of impact might vary quite a bit, too. I'd lobby
for a lab situation, where the ear-muffed player held the racket
hanging stationary downward and a machine shot a ball at it, hitting
various parts of the net. The player could then be asked to record his
blind impressions.

Has this been done? Probably not, for the same reason: There's nobody
who'd profit from the test. And especially, the company pushing the
fancy material certainly wouldn't benefit from a null result.

- Frank Krygowski


>
> Carl Fogel

 

[jim beam]

[email protected] wrote:
> jim beam wrote:
>
>>... you sum the
>>argument up perfectly. it's just like the "aero spokes make no
>>difference" argument. truth is, there is a measurable difference.
>
> it
>
>>may be comparatively small hence the "a drop in the bucket" argument,
>
>
>>but if a single percent is what it takes to differentiate between 1st
>
> &
>
>>2nd, then bladed spokes /do/ matter. it's all about the win, right?
>>when was the last time you saw F1 won by a 5% or 10% time margin?
>
> how
>
>>about the tour? even a 0.05% margin is worth it.
>
>
> So in the "Tour de Comfort" a 0.05% reduction in road vibration
> transmitted to your butt will "win"?
>
> Maybe if a person rides exactly 30 miles before saying "Wow, those
> annoying sonic-frequency buzzes transmitted through the seat stays are
> NOW beginning to bother my super-sensitive butt," they may be able to
> ride an extra 80 feet before making that same statement. Whew! Who
> wouldn't pay a premium for _that_? ;-)
>
>
>
>>returning to frame materials, composites /do/ measurably reduce
>>transmission of road vibration. that's fact.
>
>
> In your humble opinion?
>
>
> amazingly, actual testing
>
>>has even been cited in this thread [shock, horror].
>
>
> Hmm. I recall one unreadable graph posted without explanation of how
> it was generated, and available only hidden deeply in a company's
> advertising literature.
>
> Here's what "actual testing" should look like for this issue: You'll
> need an accelerometer measuring vertical acceleration of the top part
> of the bike saddle, when a rider is sitting on the saddle and the bike
> is being ridden on an appropriate road surface.
>
> This is not cheap, but it's not really rocket science. If a company
> the size of Trek really had something to show, I think they could have
> used this method to show it within two weeks or less.
>
>
>>first time i read the r.b.t. grouches bleating these same old
>
> arguments
>
>>about carbon seat posts, my reaction was to actually buy one & try
>
> it.
>
>>i was pleasantly surprised to learn that it /did/ take some of the
>
> sting
>
>>out of the road. pre-ride, my expectation, based on the extreme
>>pseudo-tech convictions i'd read, was that there would be nothing.
>
> but
>
>>that was /way/ wrong. next, i tried carbon forks. even better - no
>>hand numbness on long rides. conclusion; beware the retro-grouches.
>
>
> Alternate conclusion: Beware the placebo effect. It's powerful.

willful denial. it's powerful.

>
> You know, if you've got the equipment, you _could_ set up a blind test.
> (Actually, better do it double-blind, since you're clearly not neutral
> on this issue.) Can you get some truly neutral riders, use the same
> bike while changing the seatpost and hiding the seatpost from the
> riders, and record their blind impressions? It might make an
> interesting article.

interestingly frank, i did do that with a friend of mine. two posts
covered in insulating tape. guess what the result was.

>
> Although, FWIW, I'm not as skeptical of CF seatposts and front forks as
> I am of CF seat stays. The difference is, I think a competent engineer
> could design a CF fork or a seatpost that had significant deflection to
> absorb vibration.

contradictory illogicality.

>
> But to design a seatstay that magically removes vibration despite being
> rigid would be akin to magic.

it's not frank. go to materials school.

>
> And while there are plenty of people who believe strongly in certain
> kinds of magic, it tends to go away when you hook an accelerometer to
> it.

scientists /do/ rely on instruments, not some bizarre mixture of faith &
vehement denial.

>
> - Frank Krygowski
>

 

[Mark Hickey]

jim beam <[email protected]> wrote:

>[email protected] wrote:

>> But to design a seatstay that magically removes vibration despite being
>> rigid would be akin to magic.
>
>it's not frank. go to materials school.
>
>> And while there are plenty of people who believe strongly in certain
>> kinds of magic, it tends to go away when you hook an accelerometer to
>> it.
>
>scientists /do/ rely on instruments, not some bizarre mixture of faith &
>vehement denial.

Well then, that does bring up the question as to why no one's been
able to offer any scientific reason that the CF stays "work", other
than at the level that's used in glossy ads written by marketing types
who wouldn't know a modulus from a city bus.

But now's your chance (again...).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Phil, Squid-in-Training]

Mark Hickey wrote:
> jim beam <[email protected]> wrote:
>
>> [email protected] wrote:
>
>>> But to design a seatstay that magically removes vibration despite
>>> being rigid would be akin to magic.
>>
>> it's not frank. go to materials school.
>>
>>> And while there are plenty of people who believe strongly in certain
>>> kinds of magic, it tends to go away when you hook an accelerometer
>>> to it.
>>
>> scientists /do/ rely on instruments, not some bizarre mixture of
>> faith & vehement denial.
>
> Well then, that does bring up the question as to why no one's been
> able to offer any scientific reason that the CF stays "work", other
> than at the level that's used in glossy ads written by marketing types
> who wouldn't know a modulus from a city bus.
>
> But now's your chance (again...).

In order to find this information out, we should look to people who have
already done the research, such as Specialized. Since I'm not a materials
engineer, I wouldn't really know how to begin asking, but a request of the
relevant, legible materials from Specialized just might be the ticket to
getting some hard data.

--
Phil, Squid-in-Training

 

[jim beam]

Phil, Squid-in-Training wrote:
> Mark Hickey wrote:
>
>>jim beam <[email protected]> wrote:
>>
>>
>>>[email protected] wrote:
>>
>>>>But to design a seatstay that magically removes vibration despite
>>>>being rigid would be akin to magic.
>>>
>>>it's not frank. go to materials school.
>>>
>>>
>>>>And while there are plenty of people who believe strongly in certain
>>>>kinds of magic, it tends to go away when you hook an accelerometer
>>>>to it.
>>>
>>>scientists /do/ rely on instruments, not some bizarre mixture of
>>>faith & vehement denial.
>>
>>Well then, that does bring up the question as to why no one's been
>>able to offer any scientific reason that the CF stays "work", other
>>than at the level that's used in glossy ads written by marketing types
>>who wouldn't know a modulus from a city bus.
>>
>>But now's your chance (again...).
>
>
> In order to find this information out, we should look to people who have
> already done the research, such as Specialized. Since I'm not a materials
> engineer, I wouldn't really know how to begin asking, but a request of the
> relevant, legible materials from Specialized just might be the ticket to
> getting some hard data.
>
mark & phil, the charts are not totally legible, but let's see what we
can deduce.

1. the units of frequency is Hertz, [Hz], and that appears to be what
the horizontal axes are labeled as. i can't read the numbers, but
they're all 3 digits, apart from origin which is clearly zero. likely
units are hundreds of Hz, and the fuzz appears to accord with 100, 200,
300, etc up to 600Hz.

2. the vertical axes are not clear regarding units - could be english or
metric. they may also be sensor output or they may be g's. but the
length of the numerical labels clearly indicate a log scale.

3. we also have red & blue lines, from which "front axle" & "rear axle"
can be read, both for blue lines. therefore, even though illegible, the
reds must be handlebar & saddle.

with that much understanding, we can now look at the data. it's clear
that for good chunks of both graphs that there /is/ about an order of
magnitude difference between red & blue. because of sensor locations,
this differential /has/ to be resulting from some property of the frame
system. [and to be clear, this is /after/ any effect of the
tire/wheel.] it's also clear that the differential is greater for
higher frequencies than lower.

interpretation? we clearly have a frame system that /is/ shown to
attenuate vibration by up to 10x, generally better at higher frequencies
than lower. if we assume frame design is conventional [the pic /is/
fairly clear] and that the frame joints are comparatively rigid, this
measurement differential /is/ a function of material.

receipt of the graphs by carl fogel will doubtless clarify units of
measurement.