For Sale: Clearout: road & bmx parts

well i figured it would be cheaper to get that and bolt it ontop of my current post (a stock one from an old racer) than try and guess the size i have. it has the top part that goes in and it happens to be the same diameter as a quill stem. i dont have any callipers so i cant find out the size of the post to buy a new one. and also i would like a seat post wih no offset

do you think i could bash it over the top of my post or is it just too small?

If its exactly the same diameter as a quill stem I don't think it will fit without taking some metal of the inside of the post. I could probably fit the 1A in but only because it has a slotted section.

And to be honest it sounds like quite a bodge job, whereas borrowing a set of calipers or taking the existing post to a local bike shop who should easily be able to measure it accurately, then sourcing a cheap post of that size shouldn't be too hard to do.