I have a square taper bottom bracket. How can I tell whether it is a J.I.S. or ISO taper with a minimum amount of disassembly?
FWIW, it's a Ritchey from 2004. However, it would be nice to get answers that apply to other brands as well.
The width across the narrowest part of the flats (end of spindle):
JIS = 12.65mm
ISO = 12.33mm
I can't find anything that states exactly what size the taper goes down to either, so you would need a known JIS/ISO to compare with. Other sources conform they are the same angle though. Minimum disassembly will be taking off one crank.