Box One BMX Disc Brake Adapter – Standard Dropout


Box One BMX Disc Brake Adapter – Standard Dropout



The all NEW Box Disc Brake Adapter is designed to help improve braking control on frames where disc brakes were not standard. Compatible with 2 types of dropouts and 3-10mm hubs, in the right configurations, the Box Disc Brake Adapter goes over your hub’s axle and mates with the frame’s dropout, allowing mounting of a standard post mount disc brake caliper.

Please note this product is NOT universally compatible and we strongly recommend reading the Compatibility and Installation instructions for details before purchasing.

This version is compatible with standard 10mm dropouts without inserts. Please see the compatibility section for more details.

Related Components


  • Box Three Pro Disc Hub
  • Box Three Brake Caliper
  • Box Three 140mm Disc Brake Rotor
  • ALL Box Brake Levers
  • Box Linear Brake Cables


Adapter Specifications


  • Post Mount Caliper Compatibility
  • 140mm Brake Rotor Only
  • 6061-T6 Aluminum
  • Standard 10mm Dropout – 60g
  • Fits 3 – 10mm hubs (See Compatibility Below)
  • 150lb Rider Weight Limit


The Box Disc Brake Adapter is NOT compatible with all frames, and purchase/installation requires special attention to your frame’s dropouts for compatibility. We do not recommend composite frames for this adapter.

There are two different versions of the Box Disc Brake Adapter. This version is:

Standard 10mm Dropouts – Standard dropout configuration, dropout must be between 6-8mm thick, and have a flat inside face. Found on many frames as this is a common standard.

Both variations of the adapter come standard with two adapter rings which makes the adapter compatible with 3 brands of 10mm hubs only. Will not fit hubs with 15/20 or step down axles.

  • Box Three Pro Disc (Needs no adapter ring).
  • Stealth 10mm Disc (Requires S-Spec adapter ring).
  • Onyx 10mm Disc (Requires O-Spec adapter ring).









Rotor Size