Originally Posted by
genejockey
I used a beer can shim to stop a 27.2 seatpost sliding down the 27.4 seat tube on the Battaglin, before I got a 27.4 seatpost. Mind you, moving that 27.4 seatpost is a chore. 27.2 keeps slipping, 27.4 requires a lot of force to insert or move. I'm thinking it's really a 27.3.
A great deal of experience says a slice of plastic water bottle works much better. More grab.