Originally Posted by juvela

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thanks very much for this additional information

a CH bottom bracket thread is usually considered to limit the national origin to CH & FR

serial placement would seem to eliminate some of the major CH producers such as Allegro, Cilo & Mondia

France had not begun employing Japan frame building bits when this was made which makes one lean toward a CH origin...

perhaps some of our CH experts shall be able to shed illumination here...

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Edit:

estimate your frame to have been produced in the 1974-77 time

here are two links giving an overview of some of the CH marques

the first one unfortunately ends in roughly the early 1960's, at least shows examples from the various producers...

Swiss Bicycles | A website about Swiss Bicycles

Swiss Classics

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