Don,
I would imagine others have used this approach to the seat post. I plan to use this trick on my "AeroTour" frame project. What one needs to realize is that the seat tube should have an internal sleeve to accomodate the expansion inside. Therefore, the post should be about 25.0mm in diameter so that the wall of the tube can be increased.
This approach deffinitely would not work on a carbon frame without extra consideration.
Get the new TREK and off it immediately, if you ask me. Then buy something vintage that will last.
Brian Baylis
La Mesa, CA
My modern (1998 TREK 2300) superbike just split its aluminum seat lug at the base of one of the lug ears, and the frameset is ruined. I have held a funeral and am sending it to that great crematorium in wisconsin for recincarnation as a completely different frameset from the bike gods at TREK.
This got me thinking about internal expander seatposts. Jan Heine tells me that expander seatposts are an "Alex Singer" exclusive feature. Is this really true ?? Did any other maker ever sell expander seatposts ?? By this I mean a seatpost that operates upon the same principles as a quill stem.
Alas, my bike was 3 tubes carbon and so an expander would probably split open the carbon tubes and would therefore not solve my problem.
- Don Gillies
San Diego, CA