Carbon Fiber Seat Stays = Better Ride?

Where's the rigid truss bridge in their scheme of things

The front "triangle" of bicycle frames is not a triangle, and it
doesn't have hinges at the corners. Simplistic analysis of it as a
truss gets you nowhere.

The fork/steerer imparts bending moments to the top tube and down tube
(the wheelbase shortens and lengthens noticeably as the fork flexes
fore and aft, most of that is in the fork/steerer itself, but part
comes from frame flex).

Likewise the seat post can impart a bending moment to the seat tube,
top tube and seat stays if the rider's weight is offset from its centre
line (which it normally is by a few cm.). So I have no problem
believing that different materials, wall thicknesses, etc. in the tubes
of a bicycle frame can have an effect on the ride at frequencies that
are relevant (up to a few tens of Hz, I suppose) due to differences in
stiffness.

That said, I doubt that the seatstays have much of an effect. It looks
to me like the larger tubes that make up the front "triangle" would
dominate.

The damping qualities of CF are, as has been pointed out, in the wrong
frequency range to help comfort.

Bottom line: I am *very* sceptical about the supposed magical
properties of different types and shapes of seatstays.

On a related note I would never buy a Colnago as a matter of principle,
because they put those ridiculous diamond-shaped holes in their chain
stays and propagate the very worst kind of techno-babble in their
marketing bumf.

--
Peter Headland

pinnah wrote:

Pat Lamb wrote:
(Isn't it pathetic that I feel driven to include such a disclaimer?)

Might I suggest,

"Transgressing the Boundaries: Toward a Transformative Harmonic
Absorbtion of Road Shock"?

[my apologies to Alan Sokal]

We're getting closer... but there's no cool acronym yet. You gotta
have a cool acronym if you want people to waste, errrr, spend, errrrr,
invest money in your bull..., errrrr, technology.

Maybe

Patented
Linear
Area
Composite
Elongation
Boundary
Obfuscation

Total nonsense, but that's kinda the point to much of the marketing
technobabble, right?

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

Quoting Sandy :
Just zis Guy, you know? a réfléchi, et puis a
You choose to believe the subjective,
we prefer the objective. In particular we prefer it because, when the
degree of subjectivity is reduced (e.g. by obscuring which tubeset is
used for a bike) it turns out that it is suddenly much harder for the
riders to make the "right" judgment.
To say a machine can measure tenths of a millimetre more accurately, fine
with me. To say that measurement of one factor - vertical deflection of a
seat-stay - is the _only_ relevant measure of ride quality,

But no-one _has_ said that.

What has been claimed is that vertical deflection of the seatstays is
_a_ relevant measure. We disagree with that, because we can measure that
and see that it is very small regardless of frame material.

So we have to abandon any pretence that non-blind tests are of any
value whatsoever except as a test of fashion.
You will not have non-blind tests, except for variations on a single model
frame. Well, unless you styrofoamed all the pieces, I guess.

I think you mean "blind tests"; but, again, the fact that a blind test is
difficult does not mean that a non-blind test becomes of any more value.
--
David Damerell Kill the tomato!
Today is Mania, May.

Quoting Sandy :
a réfléchi, et puis a déclaré :
You seem to be scrupulously avoiding that. We've tried to discuss
relatively definite criteria - vertical shock and vibration
transmission - but you hint at other unspecified criteria having
little or nothing to do with the title of the thread.
You want vertical shock (Ithought you had settled on "deflection") and
vibration transmission to define "ride quality" ? OK. It's your religion.

Lying about Frank's views will not do you any good.

It's the "damping carbon fibre" crowd who claim these issues affect ride
quality, by claiming that different frame materials have radically
different properties. We say they don't, and the engineering backs that
up; but neither Frank, nor Guy, nor I, nor anyone else is saying that, for
instance, geometry can't affect ride quality.
--
David Damerell Kill the tomato!
Today is Mania, May.

Quoting Sandy :
David Damerell a réfléchi, et puis a
Oh, you don't want to discard the evidence? Good. Let's accept it,
then, and move on.
Accepted as recollections, not more.
Ah, so you want to occupy a sort of weaselly position where you don't
really accept it, but you don't quite come out and say so.
If anyone reading here has a fresh (less than 3 months old) recall of the
article, and what it says, very specifically, let me in on it.

Weasel weasel weasel. Either you believe it or you don't. What you're just
doing now is smokescreening.

The magazine reviewers clearly had their reports distorted by
preconceived notions, since they did not report the same results in
a blind test. You say that does not happen when one is honest.
Therefore, you are saying that they are dishonest.
I guess they were lousy reporters - what do you think ?
I think you're trying to distract the issue. Your remarks said they
were dishonest. Why was that?
Never wrote or implied that. Not once.

Yes, you did.

I wrote;
"But we know for a fact that rider reports are not reliable; that
there is a very strong effect in terms of preconceived notions."

You wrote; "No, that's not true. Not if it's honest."

These riders obviously suffered a strong effect from preconceived notions,
given that their reports were completely different when those notions were
not permitted to interfere. Therefore, from what you wrote, this was not
honest. Dishonest means not honest.

The people involved were regular magazine reviewers; they constantly
engaged in non-blind reviews of bikes. That's sort of the point.
Not the point - not done with the same bikes, perhaps ; not done with the
same scope of review, perhaps.]

Smokescreen smokescreen. You won't quite come out and say you don't
believe it...

So you're saying that other than geometry and lateral stiffness,
nothing distinguishes frames for ride quality ?
I'm saying that seems likely, yes.
Interesting ...

Well, what other factors do you think are relevant?

Do you think the quote (in another
posting) from Seven (to the effect that vertical compliance can be
modified by selecting different tubes) is inaccurate ?
Yes, I think that's completely untrue,

To be clear; I don't think it's untrue that vertical compliance can be
modified. I think the implication - that it can be modified so as to have
significant results - is untrue. It's like saying that the bike can be
painted to vary ride quality. I agree that bikes can be painted different
colours, but...

because the difference is
between tiny and teeny-tiny in a system with much larger elements of
vertical compliance. You only get significant vertical effects from
components like suspension, sprung saddles, etc.
OK, that's how you see it. I can accept that this is your opinion.

No, this is not purely opinion. It is a matter of fact that vertical
deflection of frame tubes is tiny compared to vertical deflection in other
elements in the system such as tyres, but that components such as sprung
saddles offer significant vertical deflection. You cannot sensibly deny
that.
--
David Damerell Kill the tomato!
Today is Mania, May.

But those 'fish lips' can be used to carry a spare tube!!

David Damerell wrote:

Quoting Sandy :
David Damerell a réfléchi, et puis a
Sandy wrote:
So you're saying that other than geometry and lateral stiffness,
nothing distinguishes frames for ride quality ?
I'm saying that seems likely, yes.
Interesting ...

Well, what other factors do you think are relevant?

Possibly weight, for suitable definitions of "ride quality".
I'm also currently agnostic on the difference fork "springiness" can make.

--
Benjamin Lewis

Although the moon is smaller than the earth, it is farther away.