Carbon seat post recommendation ?

Ron Ruff said:

jim beam said:

"I don't think... " so you don't have one then? is that a qualificaton
for advice? or is it just opinion based on other r.b.t blowhards?

Yes, I don't have one...

And no, I'm basing it on on the fact that the seatpost does not deflect
enough to cause a difference in "feel", or damping.

That depends on several factors, including the length of exposed post,
diameter, wall thickness and material of the post, rider weight, and
(if the post is CFRP) the lay of the fibers in the post.

I think it's safe to generalize the way you have when the bike in
question has traditional geometry and is traditionally sized (with a
level top tube and a "fistful" of exposed post). Throw a sloping top
tube or a too-small frame into the mix, and the post can easily flex
enough to make a difference in perceived ride quality. And it's clear
to me that flex in the seatpost can affect comfort substantially.

CFRP tubing can be amazingly stiffer or way more flexible than metal
tubing of equal weight, depending on the density and orientation of
fibers in its structure. So it's not accurate to characterize CFRP
posts as a whole for their ability or inability to flex noticeably.

What a CFRP post will *not* do is damp vibration significantly. CFRP,
like metal, will ring for hundreds of cycles if struck, so there is
obviously no significant damping there for our purposes. What keeps it
from ringing while you ride is the portion of the system that does have
damping qualities: tires, saddle and (more importantly) your body.

Quoted message said:

As a side note, I recall Zinn asking two Italian companies if their
carbon bars and stems would provide good damping. They replied, "No,
they are quite stiff". But of course Easton said, "Yes". Maybe the
whole damping BS is only for US consumption...

Because of the nature of CFRP materials, they could all have been
correct. More likely, they were just telling Lennard Zinn what they
thought would impress him, but that's another matter.

This all misses the point in that the seatpost is really the wrong
place to try to enhance a bike's comfort. A good saddle will make a
much bigger difference in comfort for a much lower cost.

Chalo Colina

Jeff Starr said:

On Mon, 21 Nov 2005 23:40:10 GMT, "Jay S. Hill" <[email hidden]>
wrote:

Have you ever tried crushing a CF seatpost?

No, but I did it accidentally by overtightening the seat binder bolt.
From what I've read, and after talking to a very good mechanic (Nello)
here in Austin, it's not that unusual. He doesn't reccommend carbon
posts because of this.

Chalo said:

Ron Ruff said:

jim beam said:

"I don't think... " so you don't have one then? is that a qualificaton
for advice? or is it just opinion based on other r.b.t blowhards?

Yes, I don't have one...

And no, I'm basing it on on the fact that the seatpost does not deflect
enough to cause a difference in "feel", or damping.

That depends on several factors, including the length of exposed post,
diameter, wall thickness and material of the post, rider weight, and
(if the post is CFRP) the lay of the fibers in the post.

I think it's safe to generalize the way you have when the bike in
question has traditional geometry and is traditionally sized (with a
level top tube and a "fistful" of exposed post). Throw a sloping top
tube or a too-small frame into the mix, and the post can easily flex
enough to make a difference in perceived ride quality. And it's clear
to me that flex in the seatpost can affect comfort substantially.

CFRP tubing can be amazingly stiffer or way more flexible than metal
tubing of equal weight, depending on the density and orientation of
fibers in its structure. So it's not accurate to characterize CFRP
posts as a whole for their ability or inability to flex noticeably.

What a CFRP post will *not* do is damp vibration significantly.

damp is the wrong word. attenuate is better.

Quoted message said:

CFRP,
like metal, will ring for hundreds of cycles if struck,

for some frequencies, yes. not others. the transmission spectrum is
radically different.

Quoted message said:

so there is
obviously no significant damping there for our purposes.

these "so obviously" arguments make no sense when based on a false
assumption.

Quoted message said:

What keeps it
from ringing while you ride is the portion of the system that does have
damping qualities: tires, saddle and (more importantly) your body.

Quoted message said:

As a side note, I recall Zinn asking two Italian companies if their
carbon bars and stems would provide good damping. They replied, "No,
they are quite stiff". But of course Easton said, "Yes". Maybe the
whole damping BS is only for US consumption...

Because of the nature of CFRP materials, they could all have been
correct. More likely, they were just telling Lennard Zinn what they
thought would impress him, but that's another matter.

This all misses the point in that the seatpost is really the wrong
place to try to enhance a bike's comfort. A good saddle will make a
much bigger difference in comfort for a much lower cost.

Chalo Colina

rs said:

I've got a low-end road bike, Giant OCR3 and would like to get a little more
damping, thinking a carbon seat post would help. Obviously I don't need the
lightest but is there a brand recommendation for a fairly inexpensive and
decent one for a road bike?

I needed less setback so I sold my Thomson Al seatpost & got a USE Alien
carbon one hoping for a more damped ride in the bargain. I can't feel
the diff. I think there is a lot of nonesense in the Great Materials
Debate.

I'd look for other things such as seat adjustablity in a post. My Alien
isn't very adjustable which might have turned out badly, but the
standard place of the seat worked out ok for me.

Quoted message said:

I think it's safe to generalize the way you have when the bike in
question has traditional geometry and is traditionally sized (with a
level top tube and a "fistful" of exposed post). Throw a sloping top
tube or a too-small frame into the mix, and the post can easily flex
enough to make a difference in perceived ride quality. And it's clear
to me that flex in the seatpost can affect comfort substantially.

The OCR series are Giant's 'non-racing' compact bikes. TT slopes
fairly dramatically.

SYJ

John Forrest Tomlinson said:

On Mon, 21 Nov 2005 21:27:33 -0500, Matt O'Toole
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

Shock-absorbing saddles
like the Turbomatic and Koobi *do* work. They offer a cm or so flex in
exactly the direction that's helpful, rather than the sideways waggle of a
flexy carbon or Ti seatpost. Until very recently, Turbomatics were still
popular among pros.

Quoted message said:

Stil -- this is 2004 at the earliest, or maybe this year:

Quoted message said:

http://www.cervelo.com/images/2004/voigt%20on%20the%20Soloist%20Team.jpg

I can't really see it in that picture, but I'll take your word for it.

Turbomatics seem to be universally liked, by newbies and pros alike. This
is rare with saddles.

Too bad they've been discontinued!

BTW, Mountain Bike Action magazine tested various suspension saddles
several years ago. I was surprised how much travel they provided.

Matt O.

In article <[email hidden]>, [email hidden] says...

Quoted message said:

just curious--what would be your opinion of carbon handlebars? People have
been telling me to upgrade to one as they are supposed to be great shock
absorbers. Is that true?

I'm still trying to absorb the shock from the asking price.
--------------
Alex

Matt O'Toole said:

John Forrest Tomlinson said:

On Mon, 21 Nov 2005 21:27:33 -0500, Matt O'Toole
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

Shock-absorbing saddles
like the Turbomatic and Koobi *do* work. They offer a cm or so
flex in exactly the direction that's helpful, rather than the
sideways waggle of a flexy carbon or Ti seatpost. Until very
recently, Turbomatics were still popular among pros.

Quoted message said:

Stil -- this is 2004 at the earliest, or maybe this year:

Quoted message said:

http://www.cervelo.com/images/2004/voigt%20on%20the%20Soloist%20Team.jpg

I can't really see it in that picture, but I'll take your word for it.

Thought I was missing something; thanks!

"Matt O'Toole" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

John Forrest Tomlinson said:

On Mon, 21 Nov 2005 21:27:33 -0500, Matt O'Toole
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

Shock-absorbing saddles
like the Turbomatic and Koobi *do* work. They offer a cm or so flex in
exactly the direction that's helpful, rather than the sideways waggle of a
flexy carbon or Ti seatpost. Until very recently, Turbomatics were still
popular among pros.

Quoted message said:

Stil -- this is 2004 at the earliest, or maybe this year:

Quoted message said:

http://www.cervelo.com/images/2004/voigt%20on%20the%20Soloist%20Team.jpg

I can't really see it in that picture, but I'll take your word for it.

Turbomatics seem to be universally liked, by newbies and pros alike. This
is rare with saddles.

Too bad they've been discontinued!

BTW, Mountain Bike Action magazine tested various suspension saddles
several years ago. I was surprised how much travel they provided.

Matt O.

I've been riding a Turbomatic for about 3000 miles and have been very pleased
with it. I tired about five other saddles and the Turbomatic was the only one
that worked for me. It is a much heavier saddle and it does occasionally make
wierd noises I guess from the suspension. On one of my rides I cross a wooden
bridge and I am always amazed at the shock absorbing the saddle provides. The
Turbomatic is still sold at Excel Sports for $80 and I have seen used ones on
Ebay.

Neal

Matt O'Toole said:

John Forrest Tomlinson said:

On Mon, 21 Nov 2005 21:27:33 -0500, Matt O'Toole
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

Shock-absorbing saddles
like the Turbomatic and Koobi *do* work. They offer a cm or so flex in
exactly the direction that's helpful, rather than the sideways waggle of a
flexy carbon or Ti seatpost. Until very recently, Turbomatics were still
popular among pros.

Quoted message said:

Stil -- this is 2004 at the earliest, or maybe this year:

Quoted message said:

http://www.cervelo.com/images/2004/voigt%20on%20the%20Soloist%20Team.jpg

I can't really see it in that picture, but I'll take your word for it.

Turbomatics seem to be universally liked, by newbies and pros alike. This
is rare with saddles.

Too bad they've been discontinued!

BTW, Mountain Bike Action magazine tested various suspension saddles
several years ago. I was surprised how much travel they provided.

Matt O.

The Selle Italia "Trimatic" is the most comfortable saddle I have ever
used (out of a dozen, including Flite, WTB SST, and 2 Brooks). I found I
could ride a 400K (250 mi) right out of the box without soreness --
never did that before.

Matt O'Toole said:

John Forrest Tomlinson said:

On Mon, 21 Nov 2005 21:27:33 -0500, Matt O'Toole
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

Shock-absorbing saddles
like the Turbomatic and Koobi *do* work. They offer a cm or so flex in
exactly the direction that's helpful, rather than the sideways waggle of a
flexy carbon or Ti seatpost. Until very recently, Turbomatics were still
popular among pros.

Quoted message said:

Stil -- this is 2004 at the earliest, or maybe this year:

Quoted message said:

http://www.cervelo.com/images/2004/voigt%20on%20the%20Soloist%20Team.jpg

I can't really see it in that picture, but I'll take your word for it.

Turbomatics seem to be universally liked, by newbies and pros alike. This
is rare with saddles.

Too bad they've been discontinued!

BTW, Mountain Bike Action magazine tested various suspension saddles
several years ago. I was surprised how much travel they provided.

Matt O.

The Selle Italia "Trimatic" is the most comfortable saddle I have ever
used (out of a dozen, including Flite, WTB SST, and 2 Brooks). I found I
could ride a 400K (250 mi) right out of the box without soreness --
never did that before.

jim beam said:

Chalo said:

What a CFRP post will *not* do is damp vibration significantly.

damp is the wrong word. attenuate is better.

Quoted message said:

CFRP,
like metal, will ring for hundreds of cycles if struck,

for some frequencies, yes. not others. the transmission spectrum is
radically different.

Right. But it's nonetheless a resilient material. Whether it damps
out a given frequency within thousands of cycles, or merely hundreds,
matters not a bit if your butt absorbs that energy in some single digit
number of cycles. It's still your butt (or the saddle padding) doing
the "damping", "attenuating", or whatever you want to call it, and not
the carbon part.

You are obviously pretty astute about materials properties. I'm
surprised that you subscribe to what seems like magical thinking about
the shock & vibe transmission characteristics of structural composites.
The transmission spectrum is basically irrelevant since the stiffness
of a carbon structural part is so high and its hysteresis so low
compared to the soft (human) parts of the system.

Chalo Colina

jim beam said:

Chalo said:

What a CFRP post will *not* do is damp vibration significantly.

Quoted message said:

damp is the wrong word. attenuate is better.

Can you elaborate?

--
Dave
dvt at psu dot edu

StaceyJ said:

---physics deleted (impressive, but it makes my head hurt)---

---replying to myself---

As a further illustrative anecdote, I took the same components, same
wheels, same seatpost, same saddle, same tires, blah blah blah from a
cannondale CAAD3 frame over to the Fastback. Both are roughly 3lb full
oversized aluminum frames with carbon forks. With virtually everything
else held constant, over the same roads the compact Schwinn with 23cm
of exposted seatpost delivered a noticably smoother ride than did the
traditional (horiz. tt) Cannondale with only 10cm or so of seatpost
exposed.

SYJ

(rs) said:

I've got a low-end road bike, Giant OCR3 and would like to get a little more
damping, thinking a carbon seat post would help.

#1 help : a better saddle
#2 help : larger tires
#3 help : double butted frameset
....
#27 help : carbon seatpost

'nuff said.

- Don Gillies
San Diego, CA

Donald Gillies said:

(rs) said:

I've got a low-end road bike, Giant OCR3 and would like to get a little more
damping, thinking a carbon seat post would help.

#1 help : a better saddle
#2 help : larger tires
#3 help : double butted frameset
...
#27 help : carbon seatpost

'nuff said.

OK all, I can't see how many of the writers here have actually compared
an aluminium post with a carbon fibre post. And then there are all the
theoreticians.

I have compared. I had a light Selcof aluminium seat post, mounted on a
Colnago aluminium frame. Frame is small owing to my need for shorter top
tube, so I need a lot of seat post sticking up (close to the marked
limit). I bought a Campag Record CF post and notice quite a difference.
OK, the Campag is quite a bit heavier (i.e. I didn't do it due to weight
weeniosis) but there is noticeably more flex and this is what I was
looking for, since the frame itself is relatively stiff.

I use both 23mm and 20mm tyres, depending on circumstances. Of course,
bringing the pressure from 8,5 bar down to 7,0 bar (on the 20 mm) has a
greater effect on comfort than any post swap will have.

To get that extra smoothness, though, the CF tube has helped that extra
bit. I am heavy for a rider, 72 kg (160 lbs), so that factor also comes
into play.

Just my two cents, from direct experience.

/Robert

rs said:

I've got a low-end road bike, Giant OCR3 and would like to get a little more
damping, thinking a carbon seat post would help. Obviously I don't need the
lightest but is there a brand recommendation for a fairly inexpensive and
decent one for a road bike?

I rode a True Temper carbon post for a year, decided it had too much
setback so switched back to my Am. Classic aluminum post. Saw no
difference in ride quality, and the AC post is slightly lighter.

Ken

StaceyJ said:

In looking over your post, I am curious how the equation accounts for
the heightened load of riding (seated) over large bumps. I am no
physics expert (hell, I do contract and real estate law), but it
appears that you are looking at a static load on the seatpost, rather
than any sort of dynamic loading. Perhaps a combination of the two
(dynamic loading and springy saddle) would explain the deflection?

Now you really want to complicate things! The load will certainly be
higher than the static case when you hit a bump... but how much more?
Hard to tell. If an additional load equivalent to the static load is
applied then you will get the 0.16" deflection. You could also
calculate what load would be necessary to break the post... that would
be the worst case.

Maybe I'll look at that later.

rs said:

I've got a low-end road bike, Giant OCR3 and would like to get a little more
damping, thinking a carbon seat post would help. Obviously I don't need the
lightest but is there a brand recommendation for a fairly inexpensive and
decent one for a road bike?

Rode a True Temper carbon post for about a year, decided it had too much
setback so I switched to my Am Classic aluminum post. Noticed no
difference in ride quality, and the AC post is a bit lighter.

Ken

Matt O'Toole said:

Turbomatics seem to be universally liked, by newbies and pros alike. This
is rare with saddles.

Too bad they've been discontinued!

Where did you hear that?

JT

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