Use carbon setpost slips down, what can I do?

[Gv]

Hi all, I've bought a use carbon 25mm diameter seatpost, I've also bought a shim for a 27,2 mm
seat tube, but the seat post keeps sliping down. I've used 27,2 mm seatposts with no problems. Is
there any way I can keep the seatpost from sliding down, other than changing seatpost? TIA,
Gonzalo Vilaseca

 

[Qui Si Parla Ca]

GV-<< I've bought a use carbon 25mm diameter seatpost, I've also bought a shim for a 27,2 mm seat
tube, but the seat post keeps sliping down. I've used 27,2 mm seatposts with no problems. Is there
any way I can keep the seatpost from sliding down, other than changing seatpost?

Try some boiled lindseed oil onto the post, put it in and let it 'dry' a bit.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[Appkiller]

I hesitate to suggest this but maybe get a 27.4 shim? When you tighten the seatpost clamp, does the
slit in the seatpost tube become overly tight? It may be that your shim is under spec - perhaps you
could go to your lbs and try a different 27.2 shim and maybe a 27.4? Hairspray on the post and shim?

Just thinking out loud.

App

[email protected] (GV) wrote in message
news:<[email protected]>...
> Hi all, I've bought a use carbon 25mm diameter seatpost, I've also bought a shim for a 27,2 mm
> seat tube, but the seat post keeps sliping down. I've used 27,2 mm seatposts with no problems. Is
> there any way I can keep the seatpost from sliding down, other than changing seatpost? TIA,
> Gonzalo Vilaseca

 

[Phil Holman]

"GV" <[email protected]> wrote in message
news:[email protected]...
> Hi all, I've bought a use carbon 25mm diameter seatpost, I've also bought a shim for a 27,2 mm
> seat tube, but the seat post keeps sliping down. I've used 27,2 mm seatposts with no problems. Is
> there any way I can keep the seatpost from sliding down, other than changing seatpost? TIA,
> Gonzalo Vilaseca

Degrease the inside of the seat tube and make sure the post is clean. If you are using a wimpy seat
clamp, toss it and get a Salsa with the barrel nut. That way torquing the bolt translates to
clamping the seat trube and not bending the bolt. Be careful not to over tighten.

Phil Holman

 

[Gv]

"Phil Holman" <[email protected]> wrote in message
news:<[email protected]>...
> "GV" <[email protected]> wrote in message
> news:[email protected]...
> > Hi all, I've bought a use carbon 25mm diameter seatpost, I've also bought a shim for a 27,2 mm
> > seat tube, but the seat post keeps sliping down. I've used 27,2 mm seatposts with no problems.
> > Is there any way I can keep the seatpost from sliding down, other than changing seatpost? TIA,
> > Gonzalo Vilaseca
>
> Degrease the inside of the seat tube and make sure the post is clean. If you are using a wimpy
> seat clamp, toss it and get a Salsa with the barrel nut. That way torquing the bolt translates to
> clamping the seat trube and not bending the bolt. Be careful not to over tighten.
>
> Phil Holman
The seat post is clean, as it is brand new. The shim fits ok both in the frame and in the seat post.
The slit in the seatpost is not overly tight.... I'll get a try with the 27,4mm shim. Thanks to all