Super73 Ultra Bee Brake Kit for E-Bikes | Macfox, Ridstar

This Ultra Bee brake kit for e-bikes swaps the stock bicycle-style rear brake on Super73, Macfox, Ridstar, Zooz, and Freego bikes for a moto-grade Ultra Bee caliper on a 220mm rotor. It ships pre-bled and bolts to the stock rear brake mount. No cutting, no fabrication.

What's in the box?

• 1 rear brake system, pre-bled: FactoryZ Custom or OEM Surron caliper with a steel-braided brake line to an OEM Surron master cylinder, filled with Motul DOT 5.1 brake fluid
• 1 rotor
• 1 caliper bracket

Specs:

• Ships pre-bled with Motul DOT 5.1 brake fluid - the hydraulic system is filled and bled before it leaves us, so there is no bleeding on install.
• 220mm x 2.3mm solid rotor, FactoryZ high carbon stainless steel - a bigger disc gives the caliper more leverage over the rear wheel.
• 6061-T6 aluminum caliper bracket, anodized - adapts the stock rear brake mount to the Ultra Bee caliper. Bolt-on.
• OEM Surron master cylinder - the factory Surron lever and reservoir.
• Steel-braided brake line - holds its shape under pressure for a consistent lever.
• FactoryZ Custom caliper - mechanically the Gen1 Surron Ultra Bee caliper, minus the branding. The lower-cost option.
• OEM Surron caliper - the genuine 2025/2026 Surron-branded caliper with revised internal oil routing, roughly 5% larger. The true OEM part.

Fits these models:

• Super73 ZX
• Super73 RX
• Super73 S2
• Macfox X1
• Macfox X1S
• Macfox X2 (with 180mm post mount adapter)
• Macfox X7 (with 180mm post mount adapter)
• Ridstar Q20
• Ridstar Q20 Pro
• Ridstar E26
• Zooz Ultra Urban (also called the UU)
• Freego X1
• Freego X2 Pro
• Freego X3 Pro

Some Macfox models need the stock brake post swapped for a standard 180mm post mount adapter before the bracket fits. We do not stock it. This is the one we recommend.

Ultra Bee Brake Kit for E-Bikes FAQ

Will this fit my Super73?

Yes, on the Super73 ZX, RX, and S2. The caliper bracket bolts to the stock rear brake mount. Check the full list above for Macfox, Ridstar, Zooz, and Freego.

Do I need any other parts?

On most listed bikes, no. The Macfox X2 and X7 need a standard 180mm post mount adapter in place of the stock brake post. It is inexpensive and linked above.

Is it pre-bled?

Yes. The caliper, steel-braided line, and master cylinder arrive filled and bled as one system. Mount it, route the line, and set the lever.

How hard is the install?

Bolt-on. No cutting, drilling, or fabrication. You remove the stock rear brake, mount the bracket and rotor, and bolt up the caliper and master cylinder.

Which caliper should I pick?

The FactoryZ Custom caliper is the Gen1 Ultra Bee design without the Surron logo, at a lower price. The OEM Surron caliper is the current genuine Surron part, slightly larger with revised oil routing. Both bolt to the same bracket.

Is this a front or rear brake?

Rear only. Your front brake stays stock.

What brake fluid does it use?

Motul DOT 5.1. The kit ships filled with it, so top off or rebleed with the same fluid. Do not mix in mineral oil.

Can I get a different rotor size?

No. The kit ships with one rotor: the FactoryZ 220mm x 2.3mm solid rotor, matched to the included bracket.

Ships from USA!