Build your singlespeed or fixie bike around Surly's Ultra New Roadie Rear Hub. This gorgeous hunk of aluminum has the capability you need and reliable sealed bearings, too! It sports threads for a track cog and lockring on one side and a freewheel on the other so you can decide how you want to roll. Plus, this hub's 130mm width fits most road frames and the hollow chromoly axle provides a flex-free ride as well as simple quick release skewer compatibility.