I have a quick release seat post and a lightweight cable threaded through the seat rails to deter anyone passing from lifting it out. It wouldn't be too difficult to cut through but you can't guard against everything in life!
Hi row,
Have a look at the Zefal Lock'n Roll system http://www.zefal.com/en/locking-pins/93-lock-n-roll.html
You set the seat/post to the required height and if you ever need to adjust or remove it you have to turn the bike upside down to unlock it
Take it with you. Most parked bikes around here are left without the seat and seat post on which also discourages ride away theft. Method requires a backpack however.
Take it with you. Most parked bikes around here are left without the seat and seat post on which also discourages ride away theft. Method requires a backpack however.