Senior Member
Join Date: Mar 2012
Location: Niagara Region, Canada
Posts: 1,455
Bikes: 1970s Alex Singer, 1960s Peugeot PX 10, 1960s Bertin C37, 1973 Carre Bertin C 37, 1972 Carlton Kermesse, 1981 Peugeot PX 14 Super Competition
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fredlord-
LV2TNDM is correct. Any metal frame will have a non-round seat tube. The welding or brazing leads to an out of round condition due to heat distortion and typical manufacturing does not address this. Every metal framed bike should have the seat lug opening reamed, de-burred, radiused and honed. That will prevent marring or stress riser notching of the post and will allow for uniform and the minimum clamping force necessary on the post.