Box One BMX Disc Brake Adapter – Sliding Dropout


Box One BMX Disc Brake Adapter – Sliding Dropout



Box Disc Brake Adapter

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 specific sliding plate dropouts with 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
  • Dropout With Insert – 65g
  • 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:

Sliding Plate Dropout – Found on many Thrill, Haro, DK and Stay Strong aluminum frames.

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