Extension Modification Kits-100mm and 120mm Easy Install Bafang BBS02

Unfortunately there is nothing physically binding the extension to the shaft, so when you try to tighten the bottom bracket, you are essentially pulling the extension towards the drive axle end bearing/nut, which cannot sustain any load. The solution I feel is best is to drill and tap 4 holes, with studs to prevent any movement, and an epoxy applied where the extension meets the original housing.

Came fast and worked as described