NIU XQi3 Rear Brake Assembly Polini Belt Most 139QMB engine cases require

Most 139QMB engine cases require machining or cutting to fit the larger cylinder skirt

Not legal for use on pollution-controlled vehicles in California or on public roads

This master set includes 12 weight sets ranging from 6g to 17g — 36 rollers total — so you can test multiple configurations to find the perfect balance of acceleration and top speed for your riding style and engine setup

Why does this matter

Genuine Scooter Co: Buddy

NIU XQi3 Rear Brake Assembly Polini Belt Most 139QMB engine cases requireRestore full rear braking performance on your NIU XQi3 with this genuine OEM rear brake assembly. This is the complete factory unit caliper, bracket, and hardware ensuring a direct bolt on replacement with no modifications required. Engineered to the same spec as the original for consistent, reliable stopping power on both the XQi3 Wild and Street variants. Genuine OEM NIU replacement complete rear brake assembly Includes caliper, mounting bracket,