Is carbon comfy ?

Jimmy censored said:

My friend recons that a carbon seatpost will make my riding more comfy ..i
cant see how?

I doubt you will see any difference with 6 inches of post. Some people
have nearly 18" of post showing on a compact frame, and then it might be
worth it. The post is cantilevered out a little because of the seat
tube angle and your weight can therefore bend it.

Your friend is a victim of marketing. 5psi more or less in yout tyres
would be infinitely more apparent than changing the seatpost.

--
Peter Headland

Quoted message said:

The post is cantilevered out a little because of the seat
tube angle and your weight can therefore bend it.

..... and I seem to rememeber that carbon tubes don't take too kindly to
repeated bending.

BigRab

in message <[email hidden]>, Jimmy [censored]

(') said:

My friend recons that a carbon seatpost will make my riding more comfy
..i cant see how?

It's much more springy than aluminium and IME a bit more springy than
steel. My all-carbon road bike is, somewhat to my surprise, an
extremely comfortable ride.

Frankly I wouldn't have thought a carbon seatpost by itself would make
_that_ much difference though. A bit of difference, certainly.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; IE 3 is dead, but Netscape 4 still shambles about the earth,
;; wreaking a horrific vengeance upon the living
;; anonymous

Simon Brooke said:

It's much more springy than aluminium and IME a bit more springy than
steel.

But simply /along/ a tube (i.e., down a seatpost) the value of "more"
will be somewhere between negligible and bugger all, I'd have thought.
I think you'll need lateral spars somewhere for any degree of
appreciable flex, and a seatpost will be effectively a rigid bar made
from any of the above.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch said:

Simon Brooke said:

It's much more springy than aluminium and IME a bit more springy than
steel.

But simply /along/ a tube (i.e., down a seatpost) the value of "more"
will be somewhere between negligible and bugger all, I'd have thought. I
think you'll need lateral spars somewhere for any degree of appreciable
flex, and a seatpost will be effectively a rigid bar made from any of
the above.

It's not vertical, but about 18 degrees behind that. And moreover, the
bumps (that matter) are coming from the rear wheel, which makes the
effective angle even greater. A long seatpost may flex appreciably.

James

James Annan <[email hidden]> wrote:

: It's not vertical, but about 18 degrees behind that. And moreover, the
: bumps (that matter) are coming from the rear wheel, which makes the
: effective angle even greater. A long seatpost may flex appreciably.

I did notice a difference with my carbon seatpost (on a compact frame
with a lot of seatpost showing). It was noticable more stiff than
the ti one but did also seem to absorb the high frequency buzz
well.

I took it out though becuase I found it a complete PITA as it
kept slipping and went back to the ti one. Much more robust, and
a better solution IMO.

Arhtur

--
Arthur Clune PGP/GPG Key: http://www.clune.org/pubkey.txt
It is better to light a candle than to curse the darkness

Jimmy censored said:

My friend recons that a carbon seatpost will make my riding more comfy
..i cant see how?

The saetpost on my racing bike is only about 6 inch above the top of
the clamp so where is the give ?,...can understand a flexible
saddle......am I right or is he ?
jim

It can be. You can make carbon flex more than aluminium without doing
damage. However at only 6 inch showing, you may not notice more than
just minor softening of road buzz. On a mountain bike where you usually
have 8-12" showing, it makes a lot more difference. But then so does
running narrower 27.2 posts instead of the 31.8 oversize posts common
on some bikes.