Pre-Bled Ultra Bee Rear Brake Kit for Super73, Macfox, Ridstar & Other E-bikes

Bring Sur-Ron Ultra Bee braking performance to your high-performance e-bike with the Ultra Bee Brake Conversion Kit.

This complete rear brake conversion package combines a pre-bled Sur-Ron Ultra Bee rear brake assembly, CNC adapter bracket, upgraded 220mm rotor, spacers, and required mounting hardware.

Designed for compatible e-bikes with the appropriate brake mounting configuration, this kit provides the core components needed to adapt the larger Ultra Bee rear braking system to Super73, Macfox, Ridstar, ActBest and other compatible e-bike builds.

Important: This kit is designed for compatible e-bike applications. Fitment is not universal and should be verified before ordering.

What’s Included

• Pre-Bled Sur-Ron Ultra Bee Rear Brake Assembly
• Silver CNC Ultra Bee Brake Adapter Bracket
• 220mm × 2.7mm Rotor
• Adapter spacers
• Required mounting hardware
• Stocked and shipped directly by K. Mods

Confirmed Fitment

220mm Rotor Kit

• Super73 RX
• Super73 S2
• Super73 ZX
• Super73 Z Miami
• Macfox compatible models
• Ridstar Q20

For ActBest, Freego, and other e-bike platforms, fitment can vary by model and brake mounting configuration. Verify your existing setup before ordering.

Rotor Sizing

Ultra Bee rear brake conversions generally require a rotor approximately 40mm larger than the bike’s original rotor to properly position the larger Ultra Bee caliper.

Example:
180mm stock rotor → 220mm rotor

This kit includes the 220mm rotor.

Always verify your current rotor diameter, hub mounting pattern, wheel clearance, and brake mounting configuration before ordering.

Brake Mount / Adapter Fitment

Some e-bikes, including certain Macfox, ActBest, and similar models, may require replacing the factory brake post/adapter with a standard 180mm post-mount adapter before installing the K. Mods Ultra Bee bracket.

This additional adapter is not included with the kit.

If your bike requires one:

⁠180mm Post Mount Adapter on Amazon

Pre-Bled Ultra Bee Brake

The Sur-Ron Ultra Bee rear brake assembly arrives pre-bled for easier installation.

Shipping and handling can occasionally introduce small air bubbles into a hydraulic brake system. If the brake lever feels soft or spongy after installation, a minor brake bleed may be required to restore proper lever feel and braking performance.

Installation & Safety

This is a performance brake conversion, not a universal bolt-on replacement.

Proper rotor alignment, caliper positioning, mounting hardware, wheel and frame clearance, and hydraulic brake operation must be verified before riding.

Professional installation is recommended if you are unfamiliar with hydraulic brake systems or custom brake conversions.

Direct Ship by K. Mods

Stocked and fulfilled directly by K. Mods for faster order processing, shipping, and product support.