Rohloff Fat Bike Disc Brake Adapter for 203 mm Rotors

Item number: 63725
  • 100 day return period
  • Online since 1998
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Dissipate torque - Rohloff support adapters

With all gear hubs, the axle tries to rotate while riding. When riding in a reduced gear (1-10), the axle wants to turn backwards. When driving with a gear ratio (12-14), the axle wants to turn forward. The torque with which the axle tries to turn is called the support torque. The size of the supporting moment depends on the load and the gear engaged, and must be absorbed by an appropriate anti-rotation device on the frame. With the simple three-speed hub, a flat-milled axle in the dropouts is sufficient. With a high-performance gear hub such as the Rohloff Speedhub 500/14, the support must be much more stable because of the large gear ratio range.
To transfer the torque of the Speedhub to the frame, support adapters and a matching axle plate are required.

Technical Information:

Adapter Material:
Bolt Material:
Rotor Size:
203 mm


PM to PM:
  • Frame Mount: post mount 7"
  • Caliper Mount: post mount
  • Installation Height: 23 mm
  • Compatibility: 190 mm, 197 mm dimensions
  • Type: Fatbone
  • Manufacturer Number: 8557


The Rohloff Fatbone in combination with the CC-OEM2-190 or A12-OEM2-197 axle plate permits mounting on Fatbike frames with 190 mm or 197 mm dimensions. Furthermore, the frame requires a disc brake mount according to the Direct Post Mount standard (either on the seat stay or on the chain stay). The mounting points of the Post Mount Direct disc brake mount for the brake caliper are used to provide torque support with the Fatbone.

The following conditions must be met for safe mounting of the axle plate (190/197 mm) and the Fatbone: the Rohloff axle plate must lie flat against the frame in the area of the axle plate (R10 / 20 mm) and must not collide with other frame parts (e.g. weld seam). Only then is a trouble-free assembly of axle plate and Fatbone possible. The Fatbone functions as an adapter and thus changes the required brake rotor size to a larger diameter. Mounting to 5" or 8" brake mounts is therefore not possible.


Do not use the Fatbone on tandem bicycles!


  • 1 x Rohloff 203 mm disc brake adapter
  • 2 x bolts


  • black/PM to PM, in stock

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