I installed a Sugino RT triple and afterwards realized that one of the spider arms had a crack in it, so decided to add a 3rd ring to a Sugino AT crankset I had laying around but the small ring ends up hitting the frame. I see the AT sits further away and requires a longer spindle…. I’m pretty sure I have a 122.5 BB sealed BB on there.
I know that there are asymmetrical spindles out there where the drive side is longer, and I can do the old cup/cone style with the loose bearings. But would rather have a sealed BB and stumbled across Sheldon Browns site for bottom brackets and that crankset he has listed 3 different lengths (127.5, 122.5, and 115.5) all with + “2mm spacer” and notes that a Shimano UN72 or UN73 can be used.
what is a 2mm spacer on a square taper bottom bracket? I had no idea that a spacer can be used on a square taper? Also I don’t understand how Sheldon brown has 3 different lengths that range 12mm of difference that will fit?
If anyone knows what kind of BB I should get that will work in this situation let me know! Thanks guys!
by bruski
1 Comment
The spacer is fitted onto the driveside cup before you screw it into the frame. It effectively lengthens the spindle by whatever its width is. I have two cup and cone bbs with spacers fitted, as it enables fine tuning of the chainline.
I don’t know about the bb spindle lengths for the cranksets you have but I have two ” vintage” sugino cranksets in use and I just found the correct lengths by trial and error, since the manufacturers chainline isn’t usually the one I am aiming for.