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.

Axis measured with calliper Axis, 123mm Axis end again

Thanks in advance!


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!

  • Do you happen to have another square taper crank laying around? Jan 1, 2017 at 21:05
  • Thanks for your help. I ordered a JIS bottom bracket and will try with that. I report back in a week or two. ISO bottom bracket were more expensive so I might end up with buying a new crank if it doesn't fit.
    – Ola
    Jan 2, 2017 at 9:05
  • I'm curious, what "standard" BB did you end up switching to? I have the same bike and I'm weighing my options. Jul 25, 2018 at 16:35
  • I think it was the cheapest shimano bb i could find in the same length as before (122)
    – Ola
    Jul 26, 2018 at 20:04

1 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.

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