pstock

these questions from and my answers to an engineering / cycling friend of mine

The seat post is pantographed "Colnago" (which, beyond the unusual design is what makes it interesting. And more valuable) also marked is "Ital Manumbra.." or something suggesting it is made in Italy. Certainly would have been made by 3TTT or ITM.

Objective is to remove the seat, Yes. Liberate the seatpost.
It's become more of an academic challenge than a practical one now. The seat and post combo is perfectly fine - I was just in the process of separating my seats and posts and got stumped on this one.

Loosening (or removing) the bolt releases some of the grip on the rails. Enough that I can reposition the seat back and forwards on the rails and adjust the tilt.

Bolt can be completely removed. not stripped, not jammed. That's not the problem.

Correct. Goal is to separate pillar and clamps from rails.
It is not stuck so much as I do not see anyway to loosen the grip enough to get it off the rails.

That one-piece top of the pillar almost completely encloses the clamps.

Clench your fingers into a half circle. Now bring your thumb to the middle finger. Now back that thumb tip off a quarter inch. That is what the top of the seatpost pillar looks like.
The two clamps are inside the the hole between you thumb and fingers.
The bolt runs from thumb to Middle finger.

tighten the bolt would close the gap but loosening it doesn't not open the gap up enough to do anything.

Weird.

On 22/03/2012 1:29 PM, Steve Kruse wrote:
>
> > You're a bright guy.
>
> A font of useless knowledge, to be sure.
>
> > obviously it would be easier if you had it in hand, but do you see any
> > obvious way to get this off?
>
> If the frame is Colnago, the seatpost itself is either
> Campy (most likely), Gipiemme (less likely) or maybe
> Shimano. Is the make of seatpost non-obvious ? I
> doubt the make is Laprade or SR or some knock-off.
>
> The problem, as far as I can deduce, is that you un-did
> the seatpost bolt yet the clamp did not get loose and
> so the rails of the saddle still are locked in place. Is
> that correct ? When you say "get this off" your aim
> is to remove the saddle from the seatpost, except
> everything is still as if the bolt was still tight ?
>
> Or is the head of the bolt (recessed hex) stripped ?
>
> Or is it that, regardless of the saddle, your aim is
> to separate the pillar of the seatpost from the rails
> and clamp at the top of the pillar, but it's stuck ?
>
> Looked at the photos but didn't say Aha! yet.
>
>
>
>