Posted this in a build and wanted to share on a how to.
I was building a bmx, but this should apply to any single speed using euro bottom bracket. When the bottom bracket was assembled in the frame there was more offset on the drive side, makes sense since they're set up for multi speed.
I wanted to center the spindle in the frame for even crank arm distance to chain stay and used a short spindle for tight Q factor.
First fit, the drive side is offset outboard
Disassembled the euro bottom bracket, the threaded sleeves come off center sleeve.
Modified aluminum washers to fit inside the dark blue threaded cups and have sufficient spindle clearance on the ID.
Reassembled the bottom bracket with the aluminum shims inside the blue cups, this changes the position of the center sleeves and bearings and spindle with the bottom bracket assembly.
After a few test fits, the spindle is centered in the frame, crank arms equal distance to the chain stays.
Hope this makes sense. Shim the center shell which locates the spindle, within the threaded cups. I don't recall total shim thickness, maybe 3-4 mm.
The threaded cups have plenty of overlap on the center support still.
Been riding this for over a year, no issue.
I was building a bmx, but this should apply to any single speed using euro bottom bracket. When the bottom bracket was assembled in the frame there was more offset on the drive side, makes sense since they're set up for multi speed.
I wanted to center the spindle in the frame for even crank arm distance to chain stay and used a short spindle for tight Q factor.
First fit, the drive side is offset outboard
Disassembled the euro bottom bracket, the threaded sleeves come off center sleeve.
Modified aluminum washers to fit inside the dark blue threaded cups and have sufficient spindle clearance on the ID.
Reassembled the bottom bracket with the aluminum shims inside the blue cups, this changes the position of the center sleeves and bearings and spindle with the bottom bracket assembly.
After a few test fits, the spindle is centered in the frame, crank arms equal distance to the chain stays.
Hope this makes sense. Shim the center shell which locates the spindle, within the threaded cups. I don't recall total shim thickness, maybe 3-4 mm.
The threaded cups have plenty of overlap on the center support still.
Been riding this for over a year, no issue.
