SUNRACE cassette 12S 9-50T ULT XD

Sunrace 12S ULT XD 9-50T Cassette

The Sunrace ULT 9-50T cassette is engineered for 1x drivetrains requiring maximum development range. The 9-tooth starting cog increases the high-speed gear ratio by 11% compared to the 10-tooth industry standard, providing a total range of 555%. This configuration allows for the use of a smaller front chainring to optimize climbing capabilities without sacrificing top-end speed.

The architecture is built on seven cogs mounted across two machined aluminum spiders, ensuring optimal structural rigidity and efficient torque transfer. The 50T cog is crafted from 7075-T6 aluminum to minimize rotational inertia, while the smaller cogs are made of high-strength steel to ensure resistance against abrasion and wear.

Key Points

Extended 555% development range (9-50T). Rigid dual-aluminum spider structure. 7075-T6 alloy 50T cog. Compatible with SRAM Eagle 12-speed drivetrains. Manufacturer verified weight of 579g. Black finish for enhanced corrosion resistance.

Compatibility and Setup

This cassette is compatible with standard SRAM XD driver bodies. For installation on XDR driver bodies, a 1.85mm spacer is required. The shift ramp profiles are optimized for SRAM 12-speed derailleurs (GX, X01, XX1 Eagle). We recommend precise adjustment of the B-gap (tension screw) to ensure smooth chain engagement on the 9T cog.

Technical Specifications