Product: Rear Derailleur Pulley Wheels 12T + 14T — compatible with GX Key benefits Smoother, more precise shifting: The 12T + 14T pulley pair is engineered to deliver consistent, accurate gear changes, reducing chain bounce and shift lag. Improved pedaling efficiency: Low-friction design and steel bearings reduce rotational resistance and minimize power loss so you ride with less effort. Durable and stable construction: The combination of a plastic guide wheel, steel bearing, and aluminum alloy seal provides strength, long service life, and reliable performance under load. What this part does for you Restores or improves derailleur performance by ensuring the chain is guided cleanly through the rear derailleur. Reduces drivetrain noise and wear by smoothing rotation and cutting friction at the pulleys. Increases overall drivetrain efficiency for longer rides, faster responses, and more consistent shifting. Key features Compatibility: Specifically designed for GX derailleurs (fits GX models as specified). Configuration: 12T + 14T pulley wheel set for optimized chain handling and shift stability. Materials: Plastic guide wheel for low weight and wear resistance, steel bearing for smooth rotation, aluminum alloy seal for added strength and corrosion resistance. Performance: Low-friction, stable rotation to minimize energy loss and improve shifting responsiveness. Use scenarios Routine maintenance: Replace worn pulleys on a GX-equipped bike to regain factory-shift precision and reduce drivetrain noise. Trail or mountain riding upgrade: Install the 12T + 14T set to improve shifting reliability and efficiency under varied loads and rough terrain. Daily commuting: Upgrade or refresh your derailleur pulleys to maintain smooth, low-effort pedaling and longer component life in stop-and-go city use. Fit and installation Designed to match GX derailleur specifications. Use existing mounting hardware and follow manufacturer torque recommendations for installation. Why customers choose this set Direct compatibility with GX, clear size specification (12T + 14T), and a durable mix of plastic, steel, and aluminum materials deliver reliable, measurable improvements in shifting and drivetrain efficiency without unnecessary complexity.