Old Steel Frame & New Carbon Seatpost?

[Pierre]

Hi,
Looking for some opinions or experience on whether any of you have had a carbon seatpost fail due to being installed on an older steel frame with a traditional lug assemby. I'm in need of a seatpost with a bigger offset and like the looks of the KForce 32mm offset but have been warned against matching and old frame with a carbon post due to risk of break. The only other option I've found is a seriously heavy ditto post (300g +).

[aoe]

I don't see why that'd be a potential problem? Plenty of modern bikes using traditional lugs with carbon seatposts with no issues. And I've had carbon posts in "old" lugged frames from the 80's with no problems either.

[AgilisMerlin]

I don't see why that'd be a potential problem? Plenty of modern bikes using traditional lugs with carbon seatposts with no issues. And I've had carbon posts in "old" lugged frames from the 80's with no problems either.

ditto

[christian]

Carefully degrease seat tube (non-trivial endeavor - offer convenient child $10).
Apply carbon paste.
Enjoy.

[monkeybanana86]

I'm curious, what did the person say would harm the post? An old frame will clamp just like a new frame. If you're really worried you can get your seat tube reamed a seatpost should slide right in without twisting

[Pierre]

The framebuilder suggested that the older clamp type was not designed for carbon and that its design put too much pressure on the rear part of the seat tube which could lead to pinching (my term not his) of the carbon at this location and subsequent failure via cracking.

[Joachim]

Some suggest that turning a clamp around spreads force more evenly around a carbon post (Tom Kellogg for example). However, I have never heard of this regarding the clamping effect of a "traditional" lug. FWIW, I will be using a carbon post with a lugged steel frame with a Richissimo seat lug.

[brando]

I been commuting with a Ritchie carbon post in my steel Ciocc for a few years now with no problem. Except once it was kinda tough to pull out of there after some wet weather.

[Puget Pounder]

The framebuilder suggested that the older clamp type was not designed for carbon and that its design put too much pressure on the rear part of the seat tube which could lead to pinching (my term not his) of the carbon at this location and subsequent failure via cracking.

If you have a pointed lug that protrudes above the collar, forget it. This is a stress region. I know of a guy whose post cracked right at this area after hitting a bump (and he didn't overtorque in the first place either). The older integrated collars do not provide even clamping while the newer removable collars do.

That said, I ran a seatpost with an integrated collar with the pointed lug for a year and my post survived. If I had known of the warnings before, I probably would not have run it.

Hell, I don't even run carbon posts anymore. Thomsons for me.

[cnighbor1]

I got a Campagnolo record 31.mm carbon fiber seat post that was broken. I got it for saddle clamps for a steel chorus Seatpost missing same. The carbon fiber post was split rigth were you would clamp it. A bit scary to see

[cnighbor1]

I been commuting with a Ritchie carbon post in my steel Ciocc for a few years now with no problem. Except once it was kinda tough to pull out of there after some wet weather.

At a bicycle show a Seven rep told me not to consider a Ti and Carbon fiber mixed frame if used in Seattles wet weather. I always wondered what wet weather does to carbon fiber frames. maybe it swells just a bit

[Fixed]

I got a Campagnolo record 31.mm carbon fiber seat post that was broken. I got it for saddle clamps for a steel chorus Seatpost missing same. The carbon fiber post was split rigth were you would clamp it. A bit scary to see

I had one (campy record)do the same thing
Cheers

[oldpotatoe]

Hi,
Looking for some opinions or experience on whether any of you have had a carbon seatpost fail due to being installed on an older steel frame with a traditional lug assemby. I'm in need of a seatpost with a bigger offset and like the looks of the KForce 32mm offset but have been warned against matching and old frame with a carbon post due to risk of break. The only other option I've found is a seriously heavy ditto post (300g +).

Can crack the SP. when tightening the traditional type binder, it gets pretty oval, which 'can' damage a carbon post. Why, in the early years, with a external seat collar, you turned it 180 degrees, to help prevent damage.

[LO^OK]

Hi,
Looking for some opinions or experience on whether any of you have had a carbon seatpost fail due to being installed on an older steel frame with a traditional lug assemby.

Sorry if stating the obvious, but use a torque wrench and stay within carbon specified range (with carbon paste someone already mentioned you can even lower the values). A lot of failures are due to over tightening.

[Johnny P]

I have a carbon seatpost in a titanium frame. After 4 to 5 years, still no problems.

[djg21]

I had one (campy record)do the same thing
Cheers

I had this happen too. A 2003 Litespeed Vortex frame with an Easton carbon seatpost. I won't use a carbon post anymore. I prefer Thomsons, and if weight is that much of an issue, you can purchase the Masterpiece.

[wallymann]

no longer run CF seatpins.

retired every single one for an alloy thomson. well designed Al posts deliver 100% of CF performance (i.e., low weight) with NONE of the constraints (no special installation or maintenance issues).

just install, adjust, and forget.


I had this happen too. A 2003 Litespeed Vortex frame with an Easton carbon seatpost. I won't use a carbon post anymore. I prefer Thomsons, and if weight is that much of an issue, you can purchase the Masterpiece.

[martinrjensen]

The pointed lug (On my Serotta) is on the forward edge of the lug and any pressure would be away from the lug on the back side. i don't think a point on the front of the lug should hurt anything? If you have a pointed lug that protrudes above the collar, forget it. This is a stress region. I know of a guy whose post cracked right at this area after hitting a bump (and he didn't overtorque in the first place either). The older integrated collars do not provide even clamping while the newer removable collars do.

That said, I ran a seatpost with an integrated collar with the pointed lug for a year and my post survived. If I had known of the warnings before, I probably would not have run it.

Hell, I don't even run carbon posts anymore. Thomsons for me.

[Steve in SLO]

http://forums.thepaceline.net/showthread.php?t=77270&highlight=broken+seatpost
I had this happen with an external collar setup, so you gotta be careful no matter which seat cluster you have;

[djg21]

Something about carbon seatposts and and stems always concerned me. I'm not a Luddite, and even use Ritchey carbon handlebars which I got for the flat tops. Now that Al bars can be had with flat tops, I don't think I'd buy carbon bars again.

[rustychisel]

i don't think a point on the front of the lug should hurt anything?


Only your scrotum, should it come to that. You're welcome. :rolleyes: