I built a tall bike based on a Mongoose fat tire bike, but I don’t know the exact model. I’m trying to figure out what bottom bracket fits it, ideally a sealed-bearing BB to improve reliability.
Original bike/frame: https://www.karrotmarket.com/buy-sell/3id5d7sge3rs/?srsltid=AfmBOoq932rnoXASGd_Y5XQcgCjP5rw7Lgt6avfL4cKlxGkNHLJSSRHb
The BB shell looks close to:
- ~4 cm diameter / ~1.57 in
- 11+ cm wide / 4.33+ in / 110mm+
Attached are photos with measurements. I googled common fat tire BB sizes, but nothing seems to match. Please help me identify the BB!
by Bylbanos
5 Comments
I thought most of them were 120mm. But…spent not.
Looks like a BSA 100mm or 120mm BB with inboard bearings
Probably 120mm with shims
It’s a 120mm with 174mm axle
Trust me I just replaced one on the bike I built my wife.
You’ll need to run a small spacer on the drive side if I remember correctly. Nothing else fits right.
https://preview.redd.it/sa0klit004bh1.jpeg?width=6048&format=pjpg&auto=webp&s=652d7ce21c1a4479d85611358418517014e5f5cf
https://preview.redd.it/obyzzvub04bh1.jpeg?width=4032&format=pjpg&auto=webp&s=e257ffa12162a2552f3a6ff8392f149428d15fda