what length seatpost should I get? 300mm or 400mm?
for a medium Cotic Soul, I'm 5'9 with a 31" inside leg
.
ta

I predict 300mm will be too small. 400mm a bit too long but better than too short. I'm 5.10 and mine needs most of a 400mm post.

thanks
I thought I'd need 400ish mm – you often pay the same as 300mm, just the one I want isn't in stock in 400mm

rule of thumb is to make sure there's at least 4 fingers width of seatpost within the main triangle (i.e. below the top tube/seat tube junction).

You need 100mm of seatpost insertion in a Soul (i.e. 10mm below the bottom of the top tube). Most people need a 400mm post, but you'd probably be OK with a 350mm with that frame size/leg length combo.

magic, thanks Cy

If you need a temp post till you can get a 400mm then CRC have THESE for £7.99. Heavy as ****, but for £8 !!!

how heavy can it be?

twice as heavy as a light one?

meh

You're most welcome 🙄