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Compact AL frames - carbon seat posts(7 posts)

Compact AL frames - carbon seat postsREMan
Jul 31, 2002 7:03 AM
I have a 2001 Specialized Allex Comp that has a stiff, compact aluminum frame. The bike came stock with an aluminum seat post that (not surprisingly) doesn't do particularly good job of absorbing road vibration. The bike rides well enough, but beats me up on rides longer than about 3 hours. I'm sure others with similar bikes have found this to be an issue as well. I was thinking that switching to a carbon seat post might smooth things out a bit. Has anyone with a similar bike upgraded their seat post and did you find it made a difference?
I seriously doubt it will help.jose_Tex_mex
Jul 31, 2002 8:34 AM
I do not have experience with the setup you mentioned, thus, take my opinion for what it is worth.

However, I doubt if a change in material will help. This is because we are only looking at the post's strength/flexibiliy length wise. If you compare the compressability of the tube in Al vs Carbon, I am sure they will be equally strong.

Have you considered posts with rubber bumpers at the top? This might help.

Also, what size tires do you use? I find 23's to be the best.
I've heard carbon posts help, but don't have any experience.(nm)jtferraro
Jul 31, 2002 10:02 AM
I seriously doubt it will help.REMan
Jul 31, 2002 12:23 PM
I'm using 23s already. I've also tried dropping the pressure which helped a bit but not enough to warrant the performance hit (real or imagined).
re: Compact AL frames - carbon seat postsPEDDLEFOOT
Jul 31, 2002 9:41 AM
My Trek has a similair frame and seatpost.I noticed when I switched to Conti GP 23c tires that it seemed to smooth out the ride considerably.I also swithed to laytex tubes but I don't know if that would have anything to do with the change.Is your fork also aluminum?Maybe going to a carbon fork would make a difference.
For me it made "some" difference.shortstroke
Jul 31, 2002 4:48 PM
This is one of those topics that bring very mixed responses.
Some say it helps and some don't. I'd be intrested to see what the setups were where they apparently helped and where they didn't to see if there's any pattern.

Could it be length, brand, seat offset, rider weight ?

I have a CAAD2 Cannondale that came with an alloy seatpost. I wanted a new seatpost anyway with a better clamping system, so I tried a Weyless Pro Carbon because I liked the classic Campy style design, it's carbon and the price is good.

For me the ride became smoother. As a whole the ride is slightly more damped, quieter feeling. Of course the carbon post is a bit longer too and that may be a factor. Personally, I'm happy with mine and I think it made a positive difference.

I do agree that tires make the most noticeable difference though. And the horror stories of cracking seatpost is a worry.

my 2 bits
it will helpBlah
Jul 31, 2002 8:21 PM
It helps not because the carbon compresses, but because it flexes and bends. With a compact frame the seat tube angle is greater than that of a regular bike, therefore the force caused by your a$$ causes the post to flex. This flex will dampen the road. And even in a regular frame the natural property of carbon will dampen high frequency vibrations, but this might not be noticable. And to add to this I ride a giant tcr with a easton ct2 seatpost and have never suffered from vibration.