Thread: Bottom bracket BB UN50 replacement
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Old 09-13-23 | 12:21 PM
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maddog34
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Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike

1.. buy a Crank remover if you don't already own one.

2... remove the cranks from the spindle and measure it.

or wait for someone here to guess at the length.. i just found FOUR different length BBs for that groupset, in a quick search of the non-specific group info you provided.

if you provide an exact Part number from the crankset, someone can possibly find the length that you could have already found with a fairly easy measurement.

ran into this thread along the way.... PS.. a 118mm version of the BB-92 (Shimano's Specified BB for that groupset.) is also available online.... they are all expensive.
https://www.retrobike.co.uk/threads/...onger%20length.

i strongly advise pulling your crank.
Last edited by maddog34; 09-13-23 at 12:26 PM.
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