Seatpost length

[VeloVT]

How close can you be to the minimum insertion line and still be safe? Is this line "conservative" or is it really at the edge of the post's tolerance?

Lots of seatposts come in 100mm size gradations (e.g., 250, 350, etc). If I put a 250 mm post in my frame, I will be about 1-2 cm (roughly) from exposing the min insertion mark (though it will not be exposed). Is this safe, or kinda borderline not safe (assuming a carbon post which is likely more fragile than an alloy post)?

Wish they made them in more lengths... I suppose if I had the tools I could buy a longer length and cut it down to something in between...

[pinkychique]

The point of the minimum insertion line is to make sure that the clamp has enough surface area to grab without digging into the post or breaking the fibers. Being within a 2cm of this line should be plenty of room to keep it from being damaged, assuming that you haven't cut the seat post at all, if you still feel iffy about it, your LBS should have no problem cutting a longer one down, just make sure that the distance from the "minimum insertion line" to the end of the post is the same distance that you have after you cut the longer one down, in other words, make sure that you make your own "minimum insertion line."

does this make sense?

I hope that helps!

[Ana]

I know a lot of seatposts have instructions to make sure that the end of the seatpost which is inserted into your bike reaches past the point where your top tube joins the seatpost shaft