>>1710383You could just order a bunch of sizes if you can find em cheap and do some guess work. Shims suck.
Measuring the frame with calipers isn't that accurate
it's accurate for measuring the post, but not the hole of the frame so much. But that is a way.
you could also go to a shop which either has a bin of old seatposts in many sizes, or has a seatpost measuring rod like pic rel.
A shop that deals in such things is also a good place to ask for advice about the frame potentially being bent open or closed to fit the wrong size, and bending it back.
