Shimano BB-UN300 Square Taper Bottom Bracket 68/122.5mm mens HP Velotechnik A-Head Headset 1"

HP Velotechnik A-Head Headset 1" for Street Machine

For all models except the Speedmachine

It replaces the special bolt on the fixed (non lever) side of your bar end shifter and adds a nice little spot to attach smallish things like motor controls

but most of the view is blocked (not recommended)

For sizing

Shimano BB-UN300 Square Taper Bottom Bracket 68/122.5mm mens HP Velotechnik A-Head Headset 1"SHIMANO Square Type Bottom Bracket MTB Standard Structure Features: SHIMANO quality performance cartridge bearing square bottom bracket Better chainline stability with chain line stabilizer 3 structures available Standard, E type, chain case options Adapter material: Aluminum