What bearing Quality used for MFG in past years?

[JanJ]

Question: Say you have a bike that was built in every 10 year increment since 1920 or so...
1920, 1930, 1940, 1950, etc...

What grade of Bearing 100, 50 25, etc would have been used for Mfg, and I realize this might be MFG specific too... ??

What I'm trying to determine (And this could be another of those 'unknown' things about 1970--1980 French bikes...)

If you rebuild an old bike, based upon year, what grade of bearing do you think you're replacing?

I would assume there would be a diminishing returns issue....

Just nosy...

[cny-man]

In addition to being one of those 'unknown' things it's one of those unimportant things. It matters not AT ALL what grade you are replacing. For replacement of any bearing grade 25 is more than sufficient, 100 is perfectly acceptable and grade 10 is expensive overkill.

[JanJ]

I suspected that, but wanted confirmation...

[nfmisso]

The big jumps in bearing improvement came during WWI and WWII. For bicycle applications, WWII to present is the same.

The answer to your original question is beyond the scope of this forum, and requires considerable research.