Choosing the correct hub is critical for frame and drivetrain compatibility. This article will walk you through the most common decision points: 

• Rear hub spacing (O.L.D.): 142 mm vs. 148 mm.

• Driver interface: 9-spline belt-drive interfaces, CD33 and CD27 Powershift Hubs.

NOTE: Classified Powershift Hubs only fit proprietary Classified cassettes.
 

Rear Hub Spacing: 142 mm vs 148 mm

Rear hub spacing (O.L.D.) refers to the distance between the inside faces of the frame’s rear dropouts. It must match your frame exactly.

142 mm (12×142 mm Thru-Axle)

Common on:

• Road bikes

• Gravel bikes

• Cyclocross bikes

• Most touring bikes
   

148 mm (12×148 mm Boost Thru-Axle)

Common on:

• Mountain bikes

• Some adventure or bikepacking frames

• Some gravelbikes designed for extra wide tires

Important:
142 mm and 148 mm hubs are not interchangeable. Always follow the frame manufacturer’s specification.
If you are unsure, don't hesitate to reach out to us!
 

Driver interface

1. CD33 (HUB-CXXX-A00-A-00)	2. CD27 (HUB-CXXX-D27-A-00)	3. 9-spline (HUB-BXXX-A00-A-00)

CD33 driver interface (legacy)

Our CD33 driver is the original driver interface, with a 33mm driver, made for 11T cassettes. These Powershift hubs are currently not produced by Classified anymore, and are replaced by the CD27 Powershift Hub.

CD27 driver interface

The CD27 driver interface enables you to use both 10T and 11T cassettes using the right cassette spacer and lockring. The driver has a 27mm diameter so the smaller 10T cassette diameter can be fitted.

A CD27 is the most commonly used driver interface and is used on:

• Any bike that uses a conventional derailleur drivetrain.

9-Spline driver interface

Belt-drive or single sprocket systems require a specific hub interface to securely mount the rear sprocket.

Choose a 9-spline hub only if:

• You are using a belt drive or single speed cog with a chain (e.g., Gates Carbon Drive)

The hub is delivered with the necessary spacers to obtain the correct chain or belt line. Classified does not sell single speed or belt cogs.

Quick selection checklist

Before ordering a hub, confirm:

• Frame rear spacing (142 mm or 148 mm)

• Axle standard (e.g., 12 mm thru-axle)

• Drivetrain type (chain or belt)

• Required interface (9-spline for belt drive or single speed, CD33/CD27 for cassettes)

   

Still unsure?

If you’re between options or building a custom setup:

• Check your frame manufacturer’s documentation

• Verify sprocket or cassette compatibility

• Contact support with your frame model and drivetrain details