There was no "standard" French seatpost diameter. In general, the seatposts for top quality French bikes varied between 26.2 mm and 26.8 mm. 26.4 and 26.6 were probably the most common. These were based on metric dimension Reynolds 531 butted tubesets, but as the framebuilders on the list have pointed out in the past, the exact seatpost size used with a given seattube can vary a few tenths of a mm depending on the frame prep done by the framebuilder.
Regards,
Jerry Moos
Houston, TX
Hi folks,
I sent these queries to Eric Elman and John Quigley with whom I have been corresponding re. my PX10E. I got helpful responses but thought that I would also put the queries to the rest of the list - especially the Francophiles.
What have you others found to be the standard diameter of the seat-tube on PX10s or comparable French bikes? I had assumed that it would be 26.4 and each time I measure with the micrometer I get a slightly different measurement. I now think that it is 26.2, in fact. I certainly can't get a 26.4 post in the tube. Does 26.2 seem right? If so is the alloy Simplex post from Bicycle Classics suitable? Are there any others out there that would do - an $80 or $90 dollar period-correct Simplex is not presently on the cards!