Originally Posted by
rydabent
Cup and cone BBs need to be faced if there is any doubt. If using a cartridge, it probably doesnt make that much difference.
For the purpose of this discussion, outboard bearings have more in common with cup-and-cone than square-taper/ISIS/Octalink sealed units.
For the latter, the two bearings are in one unit and therefore parallel with each other by default, regardless of the BB shell. With cup-and-cone and outboard, how parallel they are is dependent on the BB shell faces being parallel.