This came on a Chiorda, I believe from the 60s
I was not able to find it online.
I am sure a lot of you guys have knowledge about it and can help.
Thank you.

Thun. Chiordas and others I've seen from the era had them.

Is it an urban legend that low-end Chiordas were made with prison labor? I've heard the story but I don't necessarily believe it.
Anyway if true, this could be one of those.

A Thun BB isn't the worst thing possible, but it ain't great. And with that bottom bracket shell, you can't easily upgrade to a proper bearing style either, this frame is stuck with it.

Apologies if this bike has sentimental value, but I would look for a more worthy bike to spend your time on. But I'm a notorious bike snob, feel free to ignore me.

Girardengo 62 to 64, so says the net.

I disagree, at least in the case of one Chiorda bike I worked on. Got this as a carcass missing parts and built it up as an MTB for my then-girlfriend, now wife. The BB shell was threaded Italian--with new looking white paint that had never had cups screwed in--so I only needed Italian cups to be able to install this Stronglight 99 crankset.

Cool! Sorry for the misinformation. It's been 40 years since I worked on a Thun, I thought they had larger BB shell than Italian. Good to know.
SL 99 is a great choice, period-correct and just an excellent crankset.

This all seems to raise the question as to what the cups for this setup look like.

I imagine the bearings sit deep in the cups, and that the cups could be Italian-threaded.
But somehow I'm having trouble imagining a normal-sized fixed-cup flange with wrench flats.

On the one I had--and presumably on the rest of them--it's a pair of unthreaded metal bowls with flanges like smaller versions of #64 or #66 cups for Ashtabula cranks, as below. They just pop into the BB shell and the rest of the bearing assembly gets installed normally. Not a bad setup, but one that is usually found on lower end Euro stuff; Chiorda, Crescent, Kalkoff, etc.


I was shocked when I saw it at first, taking apart a dirty, greasy BB only to discover pristine white-painted (frame color) threads in there that just had to fit a standard part. Went and fetched a pair of Italian threaded cups out of the parts drawer and...bingo!