The Shimano Tiagra FC-4550-S 9 speed chainrings are the perfect replacement for worn or damaged chainrings. The chainring teeth have been developed to work only in conjunction with Shimano HG 9-speed chains for improved contact providing more efficiency and improved power transfer. Genuine Shimano replacement chainrings for the FC-4550 cranksets available in 50T Outer ring only Shimano part numbers: 50T-F - Y1HA98050 Compatible chain Shimano HG 9-speed
