Originally Posted by
NatUp
It might be possible to go with a shorter spindle and remove the granny ring. I say "might" because I can't guarantee there won't be clearance issues. But it'll most likely work. What will definitely work is leaving it as is and adjusting the FD to treat the middle as your inner and setting the high limit screw to stop it on the outboard side. You could also take off the outer ring and buy a longer spindle.
I tried a triple with a double, it would not move over far enough to shift well, even with the limit screws out all the way.
J&B brand Origin8 sells alloy Bmx cranks down to some pretty short lengths..
BMX cranks are all singles, aren't they?
Why do you want such short cranks? And 152mm is an odd size to boot.
152mm (6") seems to be more standard than 160mm or 155mm. It's also an even size! Yes, I am vertically challenged.