Seat post safe depth?

[Ernbar]

I posted this on the wrong forum so my question is is this mark the "safe" max line I can extend up my seat post? Usually one sees a stamped lettered warning but this post has no other markings except the line. The length from the line to the bottom of the post is 2 1/2". Thanks!

 

[Mr. Monkeyarms]

Sounds about right. I usually want enough seatpost in the seat tube inserted to make it past the bottom of the top tube for strength. Otherwise the seat post is a lever and the top of the seat tube is the fulcrum.

 

[Ernbar]

Thought I had attached a picture so it’s done now.

 

[AndyA]

Out of curiosity, I went to the box of spare seat posts and measured the ones with insert marks. Most were at 2-1/2". A few were deeper, the deepest being 3".

 

[GTs58]

Out of curiosity, I went to the box of spare seat posts and measured the ones with insert marks. Most were at 2-1/2". A few were deeper, the deepest being 3".

Most all my bikes have unmarked seat posts and I leave a minimum of 2.25"-2.5" in the seat tube.

 

[morton]

Never less than the line indicates, but deeper dpending upon the weight of the rider, the quality of the bike, material of which it is made and the type of bike. A 110 pound man using his Varsity as a cruiser would be hardpressed to cause damage at even a bit above minimum. A 220 pounder riding an aluminum wally world mountain bike (sic) thru rough trails would be well advised to insert as close to the bottom bracket as possible.

I agree with Mrmonkeyarms that below the top tube is a good rule of thumb. Just remember that the more seatpost exposed the stronger the leverage action and likelihood of damage.