Solution: 24mm Seatpost
 

This thread is for everybody who has an old Peugeot or vintage French bike. I recently got a hold of an old Peugeot UO-8. It didn't have a seat or a seat post. I called 12 different bike stores all telling me that seat posts like that haven't been manufactured since the 80's and I'd mostly like have no luck finding such a thing. Fortunately, this was not the case! I stumbled on this site, http://www.yellowjersey.org/frogstem.html who has a whole section dedicated to French metric bikes! Not only can you get a new seat post, but new bottom brackets and many other odds and ends for your classic bikes! Cheers! :)

Solution for those odd ball sizes... Take a small diameter pipe that fits into the frame easily and wrap tape around the end till slides in and out of the frame snugly but not too tight - Measure the diameter (24mm)

Buy a seatpost of your choice slightly larger in diameter (alloy 25mm about 18$)

Take the pipe with the tape and the slightly oversized seat post to a machine shop and have them turn it down in diameter (10$) - Loss of 1/2mm in wall size is not significant to affect its strength...

+1, or ream it to the size need it.