The Gates Carbon Drive Spacer Kit is an essential component to ensure optimal alignment of your carbon belt drive system. Specifically designed for Shimano HG 9 Spline freehub bodies, this kit allows for precise adjustment of the belt line to prevent misalignment issues, premature wear, and belt skipping under load.

Technical Summary

Belt alignment is critical for proper operation of the Gates Carbon Drive system. Unlike a chain that tolerates some misalignment, a carbon belt requires alignment precision of ±1 mm between the front chainring and rear sprocket. Adjustment is typically made at the chainring level, but in certain installations on Shimano HG freehub hubs, adjustment at the rear sprocket is necessary. This is precisely the role of this aluminum spacer kit: to compensate for dimensional variations and position the sprocket at the exact height to ensure quiet, durable, and friction-free operation.

Technical Highlights

• Universal Shimano HG 9 Spline compatibility: Fits all standard Shimano 9-spline HyperGlide freehub bodies, widely used in the MTB, gravel, trekking, and urban bike markets.
• Ultra-lightweight aluminum construction: At only 28 grams, the kit does not add weight to your drivetrain and maintains the full responsiveness of the Gates Carbon Drive system.
• Precise alignment adjustment: Allows adjustment of the belt line to ensure the belt remains perfectly centered on the sprockets, preventing asymmetric wear and parasitic noise.
• Essential for Gates Carbon Drive installations: Compatible with Gates CDX, CDX:SL, and CDC CenterTrack systems, this kit is often necessary during initial installation or rear sprocket replacement.

Use and Installation

The Spacer Kit is positioned on the Shimano HG freehub body between the Gates sprocket and the freehub. It consists of several spacers of different thicknesses allowing progressive adjustment of the sprocket's lateral position. Installation requires removal of the rear sprocket, insertion of the appropriate spacers according to the frame and hub configuration, then reassembly with torque to the recommended specification. This kit is particularly useful when converting a chain-drive bicycle to a carbon belt drive, or when replacing a hub on a bike already equipped with Gates.

Why is Alignment Crucial?

Unlike chains that can function with several degrees of misalignment, Gates carbon belts are intolerant of the slightest alignment defect. Lateral offset causes the belt to rub against the sprocket flanges, generating heat, noise, and premature wear. In extreme cases, this can lead to belt skipping under full load, particularly in MTB or steep climbs. The Spacer Kit solves this problem by enabling fine, precise, and durable adjustment of the belt line, thus ensuring thousands of kilometers without maintenance.

Gates Carbon Drive System Compatibility

This kit is designed to work with all Gates Carbon Drive ranges:

• Gates CDX CenterTrack: The top-of-the-line series, in stainless steel, for intensive use (MTB, bikepacking, gravel racing).
• Gates CDX:SL CenterTrack: Aluminum 7075-T6 version, ultra-lightweight, for competitive applications (cyclocross, XC).
• Gates CDC CenterTrack: Versatile series for trekking, urban bikes, and e-bikes.

The kit is also compatible with installations combining a Gates rear sprocket and an internally geared hub (Rohloff SPEEDHUB, Shimano Alfine, Nexus) equipped with an HG 9 Spline body.