The system is compatible with Shimano Ultegra r8000 r8050 / Dura Ace r9100 r9150 11s rear derailleur. KCNC Wheel Bearings reduce friction, which gives you a lower rolling resistance. The system consists of Top 12t & Bottom 16t alloy pulley wheels fitted with low friction bearings and a lightweight cage made from 7075 Alloy.
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