I need to buy another seatpost for a new frame, but being a tight sod, I’ve noticed these shims on Ebay that make the seatpost tube narrower. Thinking about just buying one of these to save some money. It’s only a pub-bike. Will I die?

just make sure the bottom of the shim is below any seat stay/seattube/top tube junction and you’ll be fine.

Yes you will die.

No it probably won’t be because of the shim.

Whether the shim is ok for what you intend depends on the frame/seatpost – see the thread of woe a while back about a Devinci…

Superstar alloy ones are good quality and price!!

I use one and no issues

yes, shoudl clarify, if it’s a pub-bike I assume there’s no warranty issues arising from use of the shim.

Nah, Spesh Rockhopper Aluminium.