Hi people,
I replaced this FAG BB (73×119) with a Shimano UN-300 (73×118) which was the closest I could source cheaply.
When fully screwed in the spindle length of the Shimano also measures 119 mm. The NDS spindle side sticks out more however. I’ve tried mounting the DS crank (same FC-MC19 crank set that was on the bike before) but the crank doesn’t fully slide on and bottoms out on the BB (shell).
What is the issue here? Am I missing something? Greatly appreciate any advice!
by Broboscide
2 Comments
I haven’t had my coffee yet, but this is hurting my brain.
The Shimano UN-300 is JIS taper, right? So, assuming worst-case (that the FAG was ISO taper and the crankset was ISO taper) then the crankset should be sitting [4.5mm outboard, not inboard](https://www.sheldonbrown.com/bbtaper.html) as a result?
I’m going back to bed, because I feel as if I’m missing something stupid obvious.
Measure your BB width. Could be your using a 63mm bb for a 74mm bottom bracket