Bike Forums - View Single Post - Are there different bottom bracket thread diameters?

06-23-15 | 07:03 PM

#4

FBinNY

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From: New Rochelle, NY

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Quote:

Originally Posted by fedepresti

Ok, thanks, it's probably from a local builder (I'm from Argentina) but it has a Cinelli shell, does that mean it's an italian thread?

It depends on when it was built. Older Cinellis would be Italian, but sometime in the eighties (± a decade or so) they went to ISO or British threading. If you have a good eye one easy to tell is by the thread direction of the right cup. RH thread = Italian, LH thread = ISO. Otherwise you can use a vernier caliper, ISO ID is slightly under 34mm, and Italian ID slightly under 35mm.

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