Thursday, August 20, 2015

Broken seatpost removal...

Have not had anything too informative that has not been covered in this blog in the past, but had Paul's Space Bike come in with a broken seatpost, the end stuck fast in the frame.  That makes riding difficult if not down right uncomfortable.

You need two distinct forces to remove a stuck stub of post; mechanical and temperature.

I've never met a stuck post I could not remove yet, so though I don't relish these fixes, they are strangely alluring in their challenge.

Here was a walk down memory lane for a stuck Thomson...

Stuck Thomson post...

This ti post gave up the fight pretty easy though.

First thing I did was look to gaining some mechanical force.  Trying to grab the stub with a pipe wrench or other "crimping" style tool will only ovalize the tube and create pressure on the inside of the seat tube, increasing the difficulty of removal.  So I drilled a through hole in the remaining material that allowed the passage of a 5mm allen tool that I would then use as a lever to turn and lift with.

Next, I applied heat to the inside of the post in it's full diameter; enough to create some expansion of the seat tube and loosen the potential corrosion, but not enough to affect the paint.

Then it was a simple twist and pull with a few choice words when I cut my finger on the ragged edge of the broken post.

Inspection of the post showed that there was a distinct discoloration inside the wall of the tube about 1/8" long, possibly a defect during the drawing of the material.  Who knows, just glad that Paul is Okie Dokie and that the bike will now be on the trail again soon.