Carbon Fiber Seat Stays = Better Ride?

jim beam writes:

not aware on any bike manufacturer publishing it, but it's easily
done. just need a vibration analyzer. shock transmission spectra for
carbon composites are quite different to steel or aluminum. tennis
racquet manufacturers are much more forthcoming on this subject.

How important are the axial loads in an axe handle or tennis racquet?
How important are transverse loads in the seatstays? Do you think it
makes any differance that the ends of the tennis racquet are
completely unconstrained?

jim beam wrote:

just need a vibration analyzer. shock transmission spectra for
carbon
composites are quite different to steel or aluminum. tennis racquet
manufacturers are much more forthcoming on this subject.

Oh. Please tell us about your pneumatic-tire equipped tennis rackets,
and where I can get one.t

jim beam wrote:

it should have a noticably softer ride. materials people are very
familiar with the superior shock transmission characteristics of
composites. that's why tools like hammers that otherwise cause
repetitive strain injuries are so often made with composite shafts.
[in
this case, wood can also be called a composite.]

Perusing a random hardware store site I find:

* Claw Hammers - Fiberglass (12)
* Claw Hammers - Graphite (2)
* Claw Hammers - Steel (15)
* Claw Hammers - Wood (16)
* Rip Hammers - Fiberglass (14)
* Rip Hammers - Steel (21)
* Rip Hammers - Wood (23)

Funny thing is that prices all seem to be about the same. I'm sure
debates rage about materials on some carpentry NG.

The real analogy would be whether a composite handle buys you anything
on a rubber mallet, that's a more accurate comparison.

"Peter Cole" writes:

jim beam wrote:

it should have a noticably softer ride. materials people are very
familiar with the superior shock transmission characteristics of
composites. that's why tools like hammers that otherwise cause
repetitive strain injuries are so often made with composite shafts.
[in
this case, wood can also be called a composite.]

Perusing a random hardware store site I find:

* Claw Hammers - Fiberglass (12)
* Claw Hammers - Graphite (2)
* Claw Hammers - Steel (15)
* Claw Hammers - Wood (16)
* Rip Hammers - Fiberglass (14)
* Rip Hammers - Steel (21)
* Rip Hammers - Wood (23)

Funny thing is that prices all seem to be about the same. I'm sure
debates rage about materials on some carpentry NG.

I think it used to be that if you were pounding 16d sinkers in all day
you would use a 20-24 ounce rip hammer with a wood handle. Always a
wood handle because a metal handle would vibrate like crazy. One
would, however, use a rip hammer with a metal handle if they were
planning on doing a bunch of ripping and prying with the hammer
because that sort of activity would quickly lead to a loose or broken
wood (hickory) handle. Of course this has nothing to do with bikes,
except that Vaughan made the best mainstream wood handle hammers for
framing, analgous to Shimmano components. Good solid stuff that worked.
Then there were botique brands, things like rigging axes cut and
welded to become hammers with curved wood handles (DeLuges? or
something like that) Good, custum, expensive, low volume stuff. Maybe
analgous to components like Phil Wood and such. And so on and so on.
Of Course Estwing always made the best metal handle hammers.

Peter wrote:

Funny thing is that prices all seem to be about the same. I'm sure
debates rage about materials on some carpentry NG.


As a frequenter of both rec.woodworking and rec.bicycles.tech, I can
say, actually, no.

App

On 13 Apr 2005 09:07:28 -0700, "Peter Cole"
wrote:

The real analogy would be whether a composite handle buys you anything
on a rubber mallet, that's a more accurate comparison.

Yup.

One lbs owner whose opinions I trust says if he puts the same wheels
and seat on six different bikes and rides each of them over the same
route, he has trouble telling which frame is which. OTOH, he has had
people grouse about how harsh the ride was on a carbon-frame racer,
only to wax ecstatic about the plush feel of a cheaper, aluminum-frame
tourer. The big difference, in his opinion, was the 32 vs 22 tires,
and 20 lbs less inflation pressure on the tourer.
--
Typoes are a feature, not a bug.
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Jim Smith wrote:
jim beam writes:


not aware on any bike manufacturer publishing it, but it's easily
done. just need a vibration analyzer. shock transmission spectra for
carbon composites are quite different to steel or aluminum. tennis
racquet manufacturers are much more forthcoming on this subject.


How important are the axial loads in an axe handle or tennis racquet?
How important are transverse loads in the seatstays? Do you think it
makes any differance that the ends of the tennis racquet are
completely unconstrained?

i think that you'd know that most carbon rears incorporate curves which
affect the static loading loading element. and i think that tennis
raquets are dynamically loaded - a factor that applies to bike
componenets such as frames, wheels, tires, seat posts, etc, but
something i have never seen any one on this group has yet acknowledge.
dv/dt can be pretty constraining.

Mark Hickey wrote:
jim beam wrote:


it should have a noticably softer ride. materials people are very
familiar with the superior shock transmission characteristics of
composites. that's why tools like hammers that otherwise cause
repetitive strain injuries are so often made with composite shafts. [in
this case, wood can also be called a composite.]

the trouble with this group however is that the people making the
loudest "it makes no difference" noises would never do anything
definitive like rent instumentation that would quantify the situation -
it would prove them luddites. as for actually /riding/ a bike with such
new fangled technology? well, that's just not going to happen. no
siree bob.


Tell ya' what then... due to the total lack of any measurements (gee,
why do you suppose the manufacturers didn't try to quantify the
tremendous amount of improvement???), we'll have to settle for you
explaining to us all how much that carbon fiber seat stay
"compresses", and how, under what conditions. And then you can
compare that amount of compression to that in the tire during an event
that would compress the seat stay, and explain to us all how the
difference would be noticeable to the rider.

That'll do...

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

mark, just like different bulk materials have different properties such
as modulus, density, etc., they also have different shock transmission
characteristics. and that's it. composites have different [usually
attenuated] shock transmission spectra to materials like steel & ti &
aluminum.

the jobstian tire red herring makes no account of dynamic loading
because it never suits his arguments on this kind of subject, but the
fact remains that a tire can & does transmit shock impulse via its
sidewall /and/ it's air filling. the sidewall transmits "tension loss"
pulses. the air transmits compression just like it does sound.

jim beam wrote:

Mark Hickey wrote:

Tell ya' what then... due to the total lack of any measurements (gee,
why do you suppose the manufacturers didn't try to quantify the
tremendous amount of improvement???), we'll have to settle for you
explaining to us all how much that carbon fiber seat stay
"compresses", and how, under what conditions. And then you can
compare that amount of compression to that in the tire during an event
that would compress the seat stay, and explain to us all how the
difference would be noticeable to the rider.

That'll do...

mark, just like different bulk materials have different properties such
as modulus, density, etc., they also have different shock transmission
characteristics. and that's it. composites have different [usually
attenuated] shock transmission spectra to materials like steel & ti &
aluminum.

I don't entirely disagree with you, and do understand that different
material will transmit different impulses differently... but I can't
help but think that any "pulse" that gets by and through the tire,
across the rim, up (and down) the spokes, through the hub to the
dropout isn't going to have a tremendous amount of "square wave" left.
And it's doubly hard for me to imagine something as stiff as an
axially loaded CF tube affecting an already-muted "pulse" enough to
make a real difference. To do so would require mm+ "compression" to
make any difference even to the most finely tuned butt (no flatulence
jokes please), especially when you realize that the "difference" has
to be interpreted by that butt through a saddle designed to absorb
shock.

To me, it's a princess and the pea scenario, and I've yet to see
anything that makes me think the CF stays are anything other than
marketing. I'll gladly change my mind in the presence of data
though... but I suspect there's a very good reason the manufacturers
don't supply it.

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

" wrote:

Please explain why compression is an issue?
Grey/Black cast iron does not compress, yet its vibration damping
characteristics are why all the best machine tools use it for frames
and beds.

Don't confuse two different phenomina.

I think you're the one mixing different issues. The sheer mass of a
cast iron bed is what helps keep vibrations to a minimum. If I hit
that table with a hammer, the hammer is going to do the compressing,
not the table, right? The table has mass on its side, and
"compressing" the surface of the table would require compressing a
MUCH larger chunk of iron than the hammer has (since just under the
contact point is more iron, and more behind that, and so on and so
on...).

To grossly over-simplify the issue - for a seat stay to "damp" a
vibration, the vibration has to enter one end at one amplitude, and
exit the other end at a smaller amplitude. Forgive me if I've missed
something obvious, but the only physical phenomenon I can imagine that
would cause that effect would require the stay to compress. There's
simply no other way that a thin-walled piece of carbon fiber is going
to reduce the amplitude of impulses fed into one end.

And I think it's clear that it simply cannot compress to any degree
that would be meaningful in terms of a noticeable change in the ride
qualities of a given bike.

I'll be happy to alter my position if someone - anyone - can explain
to me how the stay could physically damp an impulse significantly. No
one's been able to do that. Ever.

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