Bicycle Mechanics - Will the real taper please stand up?

:) Please help or direct to content with info :)

what is the best way to tell if the taper (square) on a BB spindle is Italian or everyone else?

what is the best way to tell if the taper in a crank is Italian or everyone else?

thanks!

You have to look the horse at the mouth not at the hooves

It is usually the thread of the BB that is either Italian or BSC/English "everyone else", not the taper.

Italian BB cups are both right-hand thread where as with an English BB the left side cup is a right-hand
thread and vice versa.

The taper of axles varies, the most common is a two-degree taper and will work with most cranks.

To tell the taper of a crank easiest way is just by brand..

Your questions are sort of odd, don't know if I helped. What crank/bb do you have?

Figuring out the threading - English or (less common) Italian or (way less common) French is independent of figuring out the taper standard. Two ways of figuring out the latter. One is by brand (Campy, Stronglight are ISO, nearly everything else is JIS), the other is to fit a crank over the taper and see if it goes on too far (in the case of JIS crank on ISO taper) or not far enough (in the case of ISO crank on JIS taper).
Why do you ask? If you gave more info with your question, we could answer it better.

The 2° taper is the same but an ISO taper starts at a smaller square dimension than JIS.

I just miked a couple of Shimano bottom bracket spindles (certainly JIS) and they measured 0.502" to 0.504" at the ends of the taper so that should provide a reference point.

The 2° taper is the same but an ISO taper starts at a smaller square dimension than JIS.
Good info to know. Thanks.

Two ways of figuring out the latter. One is by brand (Campy, Stronglight are ISO, nearly everything else is JIS),

Are modern stronglight cranks still ISO? Also add Miche to the ISO list.