flipping the axle of an old-style BB


New Member
Aug 10, 2005
I'm converting an old piece of junk 10 speed to a fixie. Unfortunately, the chainline at the chainring measures about 48mm (center of seat tube to the outer chainring), which is too wide for the IRO hub I've got my eye on (42mm for that).

The bike has cottered cranks and an old-style BB (i know, i know, but I'm too broke/cheap to buy a new BB, crankset and chainring). I heard that I could crack open the BB and flip the axle, which would bring in the chainring. I want to know:

1. Is this is doable?
2. How to predict what the new chainline will be before I actually make the change?
3. Will the flipped axle make the left (i.e. non-drive side) crank stick out way too far?
4. Is flipping the axle preferable to just using spacers to move in the chainring?