500EX Hex Hub

This is the "500EX Hex Hub" the bore is a 1/2" Hex Hole. It is a slightly different version of the 500 Hex Hub. It is manufactured differently, as it is extruded. Also, there is a 1.124" diameter boss on each side of the hub flange, providing a location for 1.125" bore flat sprockets. Are you having a hard time keeping your sprocket concentric with your hub? This hub is the trick.