Seatpost sizes

[brucers]

In my collection of seatposts the smallest (and most prevalent) is 25.4. Are there smaller sizes?

 

[Sharky]

27.2 seems to be the most prevalent on my bikes.

 

[Hacienda71]

There are loads of sizes including sub 25.4.
https://www.sheldonbrown.com/seatpost-sizes.html

 

[Edgy Dee]

The 24mm that many old Peugeots have is notoriously hard to source.

 

[brucers]

Thanks people, I have my answer.

 

[Pale Rider]

A thicker seat post - or maybe a thinner one - is meant to give more of a cushioning effect.

I can never remember which.

 

[HLaB]

My first BSO as an adult was a weird size (I forget which one but I needed a coke can shim) but all my other bikes have been 27.2mm or 36.4mm.