YABD - vintage Bernard Carré frame, etc

[Jesper]

(06-11-2024, 05:52 PM)enkei Wrote:  Is this an excuse for me to buy a 28mm clamp-on front derailleur? ;-)

I have no clamp-ons....

Thankfully, I have about 30 of them so you're all set!

When you service the front mech check to see if it has any markings on the clamp band or elsewhere. Often there there a diameter size given on them. Not sure if Simplex did that. Now, I will do a quick check to see if I even have any Simplex stuff from the '70s since my bikes using their equipment are 1930s to '50s frames. I do know that I have a couple of the push rod style front mechs I stripped of some bike boom Peugeots, but I doubt they are marked for clamp size.
If you refer to Velobase sometimes contributors like myself will note any and all markings on the components listed, other entries often don't show even a photo (a tech. issue with that site) or any details.

Did you measure tube ODs near centers or ends? Your best bet is near center areas to avoid possible tubing that was deformed by heating; and paint is usually more evenly applied near center areas. .3 to .4 mm thickness would not be uncommon before clearcoating was used for a frame finish. So the outlier is the .6 mm of paint on the seat tube if indeed that is why you have that measurement. Also, with round tubes always measure on two different axes to ensure you get a consistent reading.