Upgrade your Shimano 12-speed drivetrain with super-smooth, accurate shifting and reduced friction. The Kolossos ST features an 18-tooth narrow-wide bottom pulley and 14-tooth top pulley on our stiffest cage yet, replacing your stock 13-tooth pulleys.

Equipped with high-quality stainless steel bearings, the Kolossos ST delivers excellent durability and smooth performance at a more accessible price point. Built for optimal shifting accuracy and chain retention—essential for XC, marathon, and enduro riders.

Ground clearance remains within 2mm of stock without hanging lower. Ships with road seals for maximum efficiency, with cross seals available for wet conditions.

Fitment: Compatible with Shimano XTR, XT, and GRX 1x 12-speed rear derailleurs. Not compatible with the latest Di2 XTR and XT groupsets