I'm no expert on Peugeots. But the size differance between the largest @ 26.8mm and the smallest @26.4 mm is only 0.4 of a mm. Not much !!
Maybe there were some inconsistancies when the frames were brazed. and this makes the tubing vary? I wonder when the bikes were assembled in the Peugeot factory if, they selectively assembled the seat posts into the frames??
Prehaps there was a conversation in the assembly shop somthing like this. "Oh no another frame from Jean Paul"!! "Quick pass the 26.4 posts some grease and the large mallet".
Who can say!
>From: "Eric Elman" <email@example.com>
>Subject: [CR]Peugeout Seatpost Size Inconsistancies
>Date: Thu, 15 Feb 2001 12:38:14 -0600
>Riddle me this Bike-Friends.....
>My 1968 Peugeot PX-10E has an original 26.8mm Simplex seat post
>My 1972 Peugeot PX-10E has an original 26.4mm Simplex seatpost
>My 1977 Peugeot PX-10LE has an original 26.6mm Simplex seat post
>All three have Reynolds 531DB French decals, all three have 1/2 chromed
>Why would they have three different seat post sizes????????????
>Eric "always finding something to keep me perpetually confused" Elman