Replace old square taper bottom bracket / ISO or JIS?

Question

I'm trying to replace an old worn out square taper bottom bracket from a Peugeot road bike from ca 1985. It uses english threads and the axis is 123 mm. So far so good.

But I cannot understand what type of taper (do I say it like that?) I have? It uses a Nervar crankset and according to Sheldon Brown it should use a ISO taper.

All suggestions for what sealed bottom bracket to buy would be great.

Thanks in advance!

Update:

I bought a standard bottom bracket and it worked perfectly. It's too much snow outside to take it for a test ride but in a week or three it'll run. Thanks a lot for all help!

Answer 1

First, very nice drawings and measurements. This makes answering easy.

According to the Sheldon Brown link, for JIS "The standard width across the flats at the end of the axle is 12.65 mm", which is very close match to your measurement. ISO would be narrower at 12.33 mm.

Many European manufacturers switched to JIS square taper before two piece cranksets arrived, so it is not that implausible that Nervar did it too. Of course, there is the possibility that an original ISO axle was already replaced with JIS at some point. If this is the case, the end of the axle should be very deep in the crank hole.

Product recommendations are not appreciated on this site, but in my experience basic Shimano bottom brackets are fine.