Originally Posted by
scale
the original shimano un71 was 73mm x 113mm, i am thinking of running a modest 1x9 drivetrain here for city and some light trail.
Would 113mm still be the right spindle length for this type of thing. I have a sram x5 front with a x9 rear i am thinking of running. IF anyone can make a recommendation here for bottom brackets that would be great. I could probably even go more modern and use a hollowtech style bb and try to source a proper length crankset i suppose. The hollowtech bbs are cheap. I am thinking of a 36 - 40 chain ring up front.
Spindle length is determined by the crankset chosen. Choose the crank first and then buy the spindle length/BB type it requires. External Hollowtech BB is for hollowtech cranks only. Until you decide on a crank the only thing you know is you have a 73mm shell width with BSA (English) threading. The direct replacement would be a UN54 (plastic NDS cup) or UN55 (Al NDS cup)