Fitting a carbon seat post

[montage]

150mm isn't much sticking out- should be fine.

 

[brodie]

Thanks for the advice guys.

I've done it, bloody hell it was tight. There was so much friction that the seat tube was too hot to touch! A 27.2mm came out but was only about 180mm long so there wasn't much post in the tube, my new one is 350mm so there is a fair bit extra in there, it was so tight that I considered cutting 100mm off but I persisted; in, out, in, out, each time a little looser. I reckon I must have lost a couple of kg in sweat. Perhaps the internal quality of the 501 isn't all that, I did open up the top of the tube and checked for burrs, etc as you suggested Mickle thanks.

Now it's all fitted I pinched the seat bolt up but probably could have left it off And I've got that little bit of extra height that I've been in need of and they're supposed to offer a little more comfort too aren't they? Oh and a whole 80g saving over my old post

The seatpost shouldn't that tight, ideally it should slide in smoothly and without needing great effort. Maybe 27.2 is too big for the frame, 501 possibly should be 27mm as it's a heavier tubing ie thicker walls.

 

[Tel]

The seatpost shouldn't that tight, ideally it should slide in smoothly and without needing great effort. Maybe 27.2 is too big for the frame, 501 possibly should be 27mm as it's a heavier tubing ie thicker walls.

Yeah I wondered that but like I said a 27.2mm came out of it, but perhaps my dad had the tube reamed out 0.2mm when he had some of the frame mods done, I don't know. It is the 501 aerospace though so perhaps that was 27.2mm....

Anyway I just pulled the post out and am now contemplating a cut. I have about 130mm of post exposed (not including the height of the clamp) and 200mm buried in the frame. How much should I cut off??? 100mm perhaps?

What's carbon like to cut anyway!

 

[Tel]

This was quite helpful http://www.eastonbike.com/downloadable_files_unprotected/r&d_files/R&D-05-Carbon.pdf but I'd still appreciate any other opinions...

 

[Tel]

How much should I cut off??? 100mm perhaps?

What's carbon like to cut anyway!

100mm it was then which still leaves 100mm or so in the frame which should be plenty enough. And carbon is okay to cut, a little easier than alloy I would say.

My post now weighs just 188g, I cut off 36g, not bad for a £15 bikehut post

(My kitchen scales have never seen so much use....saddo alert!)

 

[brodie]

Yeah I wondered that but like I said a 27.2mm came out of it, but perhaps my dad had the tube reamed out 0.2mm when he had some of the frame mods done, I don't know. It is the 501 aerospace though so perhaps that was 27.2mm....

If you have to use a lot of force to remove and fit a seatpin then that seatpin is not the right size for the frame, regardless of the size stamped on the seatpin. It's possible that the frame was not reamed to the correct size after being built.

I would say forcing a carbon post into a frame is not a good idea.

 

[Tel]

Like I said I vaguely recall my dad having the seat tube reamed by the local frame builder at the time. Now I have removed the bottom 4" it slides in and out with very little effort and the carbon in the tube is unmarked.

 

[Gazza]

Fractured

I'm on my second pin now.. in a Giant SLR frame. The problem is the design of the top tube creates a V shaped indentation into the resin of the post over time (and yes I do torque it). Eventually it created a split in the old tube and the newer one is heading the same way.. you have to be very very careful with them. I noticed my tube was made for a twin collar fitting and the Giant is only single collar so maybe that puts extra stress on the area. i tried putting a shim in to smooth the pressure but no space for that..