Originally Posted by
peeweevinson
I’m using the middle and the granny, and put a chain guard on the outer..
I have a similar setup (granny, “middle”, & chainguard) with 9-speed on my cargo bike, albeit with ‘80’s Deore crankarms. I used the same BB as used on a triple crank. It works perfectly- to the point that the front derailleur did not require adjustment after the initial installation.
(It might have helped that I have 40+ years experience working on bikes.)