Re: [CR]reply to stuck seatpost discussion

(Example: Racing:Jean Robic)

Date: Fri, 4 Jul 2008 10:22:20 -0700 (PDT)
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
Subject: Re: [CR]reply to stuck seatpost discussion
To: John Betmanis <johnb@oxford.net>, classicrendezvous@bikelist.org
In-Reply-To: <3.0.6.32.20080704110318.0144a8f8@mailhost.oxford.net>


OK, after all the helpful responses, here is my plan:

As I've been hearing about Kroil here for years, I finally found the manufacturer on the web, called the 800 number and ordered a couple of cans. When it arrives. I'm going to apply Kroil while I heat the junction with a hair dryer and let it cool for a few cycles. Then after giving the Kroil a couple of days, I'll clamp the post in a vise as Dale suggested and use the frame for a lever. As many times as we've discussed this, I don't remember the suggestion of clamping the post in a vise being mentioned before, but maybe I just forgot. Actually a couple of others suggested the same thing this time on or off list.

Regards,

Jerry Moos Big Spring, Texas, USA

John Betmanis <johnb@oxford.net> wrote: At 09:18 AM 03/07/2008 -0500, Manfred Hegwer wrote:
>
>Heating the aluminum seat post may very well work but don't heat it to the
>point of trying to melt it. You can use a torch like the one a plumber wou
>ld use to sweat copper pipe. Heat the exposed aluminum post long enough to
> allow it to conduct the heat down into the seat tube. The different metal
>s have different rates of thermal expansion. This movement will often brea
>k the bond between the two metals. I recently used this method to remove a
> pedal stuck in a crank arm.

In the case of the pedal in the crank arm, you (usually) have steel pedal spindle in an aluminum alloy crank, so heat will loosen the bond due to the higher coefficient of expansion of the aluminum. With the seatpost you have the opposite. However, heat could still help break the bond due to the difference in expansion crushing any corrosion products in the interface. Repeated heating and cooling is always good.

John Betmanis
Woodstock, Ontario
Canada