Minimum seatpost length?

[twowheelsgood]

Hi, I have a bog-standard alloy seatpost but it really is preposerously long, having around 30cm inside the frame.

How short could I cut it and still remain safe i.e. mainly not damaging the frame or risk having the post snap?

 

[chris42]

measure from the min insert line to the end then that is the safe amount you need to leave

 

[twowheelsgood]

It is not marked with a minimum insert line.

 

[Steve Austin]

At least an inch below the bottom of the intersection of the toptube and seattube is the most often head advice. If its a compact frame with a low toptube it can mean a lot of seat post still.

 

[MichaelM]

Without going and measuring, I reckon the min insert of a Thomson post on the mtb is around 11/12 cm - thats on a 44cm post. I'd say you could quite safely cut it to have an insert of 15cm (probably a bit less).

 

[twowheelsgood]

Thanks all,

I'll leave 5cm/2ins in the frame. It's actually for my hybrid. What on earth made me buy a 40cm post in the first place!!

 

[Steve Austin]

you'll want more than 5cm

 

[TimO]

Why do you want to cut it off? Is it difficult to get in, or are you just trying to save a bit more weight?

 

[barq]

you'll want more than 5cm

*looks up*

What he said.

 

[Monty Dog]

Minimum of 3x diameter - so 100mm to be absolutely on the safe side

 

[twowheelsgood]

Hi OK 10cm it is. I want to cut it because it takes a ridiculous amount of time to get in and out of a frame and it's tricky looking after a 40cm greasy pole (oo-er) when you remove it for security. As it has my Brooks attached to it, weight isn't exactly the issue!

 

[punkypossum]

I always thought you had to leave at least a third of the total length inside the frame?