Originally Posted by Landgolier
Huh? Italian is 36x24 both sides. I'm talking about using an italian threaded BB put in from the left rather than the right.
I think you're talking about flipping a spindle, not a whole BB, which is impossible on British threaded setups. Italian thread BB's unscrew because the right side is right hand threaded, which is wrong from the standpoint of bearing precession. Right hand threading on the left is "correct," so a cartridge bottom bracket installed this way should not unscrew. Jobst Brandt argues that left side cups don't precess meaningfully anyway, the effect comes from the forces of the chainring. It's those forces that I'm concerned about.
Is he saying the forces aren't great on the left side of the BB because they are the left or because they are on the non-drive side? The drive side cup is right (wrong) threaded whether it is the "left" or the "right" side of the BB.