RYET RS Full Ceramic Oversized Derailleur Pulley Wheel 13T-19T Pulley Wheel Fit For Shiman R7000 R8000 R8100 R9100 R9250 Part

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This Ryet RS OSPW is actually really good because it has properly sealed bearings. I've done about 1000km often on wet and dirty roads with it now and it spins like new without any need for oiling and stuff. I didn't open or measure the bearings but they looked like some standard sealed bearings from the outside.