Hello,
I stripped down a donor bike and started rebuilding it to give a friend.
The original crankset was fitted with the BB-5500 Bottom bracket (70mm shell, ITA threading and and 109.5 spindle lenght).
I want to mount a square taper crankset, so i tried fitting a UN-55 BB (70mm shell, ITA threading, 113 length). Somehow i can't screw the cups all the way. I measured both bottom brakets from the outer edge of right cup to the outer edge of left cup and indeed UN-55 is longer by 2mm.
Both BB being designed for 70mm shells, shouldn't their cups spacing be equal ? Or does the spindle lenght make a difference ?
I'm afraid my chainline will not be right if i don't manage to screw at least the drive side all the way.
Any help will be much appreciated !
Cheers
I stripped down a donor bike and started rebuilding it to give a friend.
The original crankset was fitted with the BB-5500 Bottom bracket (70mm shell, ITA threading and and 109.5 spindle lenght).
I want to mount a square taper crankset, so i tried fitting a UN-55 BB (70mm shell, ITA threading, 113 length). Somehow i can't screw the cups all the way. I measured both bottom brakets from the outer edge of right cup to the outer edge of left cup and indeed UN-55 is longer by 2mm.
Both BB being designed for 70mm shells, shouldn't their cups spacing be equal ? Or does the spindle lenght make a difference ?
I'm afraid my chainline will not be right if i don't manage to screw at least the drive side all the way.
Any help will be much appreciated !
Cheers