Stuck seatpost removal system (experimental)

Preface

As of 2024-04-06, this is untested. I only have a 27.2 mm variant because that's a super common seatpost size.

Motivation

• when a seatpost gets stuck in a frame, removal is best done with the assistance of a penetrating oil like PB Blaster

• generally it's best to try to twist the seatpost while pulling it out

• often, the end of a seatpost is used to apply torque via wrench or vise, or even beating on an old saddle clamped in place

  

  • however, most of these ends are simply press fit & will eventually slip once enough torque is applied

• even once the saddle is removed, there's seldom access to the main tube

Idea

• threadless stems have removable faceplates, allowing them to clamp to the middle of a tube

• threadless stems are commonly available in 31.8 mm size, which is bigger than many of the common seatpost diameters: 27.2 mm, 30.9 mm

• they're cheap enough to have beater ones to be used as breaker bars

• idea is to have a set of shims to step down from 31.8 mm to the target  seatpost size, clamp the stem on the seatpost, & induce torque on the seatpost through the stem by beating it with a mallet or putting a breaker bar through the steerer end of the stem (often 1.125")

• if grip fails, potentially sandpaper or even carbon fiber grip paste could work to help the plastic 

Rev 2 in use

• Flexure makes it easier to install the shim with 1 hand while the other hand has to juggle the stem & faceplate

• flange keeps the shim in place axially against the stem

Clamp the face plate around the shim

Apply torque

• 2024-05-19 tested last month & totally didn't work on a stuck seatpost

• printed in PETG

• as I expected, the grip between the plastic & seatpost OD is far too inadequate to apply torque