Originally Posted by Retro Grouch
Diameters aren't the same.
Huh? Italian is 36x24 both sides. I'm talking about using an italian threaded BB put in from the left rather than the right.
Originally Posted by vpiuva
It's still right hand threaded no matter which way you install it, so it's possible you've overthought this 'benefit'. But I've installed a BB backwards for a while until I found one with the correct spindle length and it worked. Can't say it was a long term test, however.
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.