I currently have a 68mm traditional 3 piece cup and cone bottom bracket.
if the cups tighten like british/iso (left side tightens right, right side tightens left) style bottom brackets, does it necessarily mean that the thread sizing is that of a british/iso style bottom bracket (1.370" X 24 tpi)?
then if this is true, upgrading to a sealed bb should work? and if it doesn't i'm screwed?
I could pull out the cups and measure the threads, but i spent a good part of today fitting/hammering/smashing/grinding the cotters all nice like to fit. I don't want to do it again.

yes a sealed bb will work for you.

Brit standard, used by Japan and exporting Asian manufacturers . too.


I went Ah Ha! when I found Cotter Presses to do those jobs,
on old cottered cranks.
pushed rather than beat them out, so they get reused.
the job got civil ..

+1

No. Especially if the bike is old enough to have cotters. If it's a Raleigh, you could have 1 3/8" X 26 tpi threading, in which case the only sealed BB that fits is a Phil Wood. (See https://www.sheldonbrown.com/cribshee...mbrackets.html ) If the bike's Japanese, it's almost certainly English threading.

it's not a raleigh. but people have aged my bike to about the 60's.

Is the brand marked anywhere? If it's not a Raleigh, there's a 99% chance it's English thread, but I ran into a couple weird ones back when I was working in a shop.

Not necessarily. For example, Swiss-threaded bikes also have left-hand threading on the fixed cup, but the diameter and pitch are the same as French. A bike shop once almost destroyed the frame of our tandem by making the wrong guess about French vs. Swiss threading.

What make is the bike?

heres the head badge. i'm thinking it was made by some department store in the 60s/70s.