Originally Posted by
Little Darwin
I am figuring on 200-250mm total length, but I would potentially like to put a small mark to indicate minimum insertion without introducing a stress riser if it makes sense. Has anyone done this? I don't have any special tooling, but I am curious if anyone has ever seen this as something worth doing, or if you just wing it, since the minimum insertion line is just a lawyer thing anyway.
The actual safe minimum insertion varies depending upon the wall-thickness of the seatpost, the seat-tube on the frame, the clamp design, etc. Without knowing the actual frame it's going into, the seatpost manufacturer will set the mark with extra safety margins.
On your particular post and frame combination, you want the post to be at least lower than the part where the top-tube joins to the seat-tube. On most frames, that's 40-50mm. And yes, you can just use a scribe-tool to mark a minimum insertion. Just 1/4" long line at the back of the post is fine.