1x Bike Rear Derailleur. 12 Speed Rear Derailleur. 13T pulleys and decreased derailleur tension prevent high chain tension in low gears. Decreased rear derailleur and chain tension in low gear. Good Compatibility: Plastic-steel composite material, light weight, good compatibility, suitable for various gear shifting models; solve various pain points, improve gear shifting response speed, and make gear shifting more labor-saving.
