If you are running a flip flop hub with only one cog or freewheel here's a great little cover for the thread on the other side.
Halo Aerorage Track 700c Wheel
Halo Track Rear Hub Double Fixed/Fixed Flip Flop 24h 32h 36h 48h
700C Fixed Gear Wheelset Bolt On Hub 9.5x100mm/9.5x120mm Solid Axle, Flip-Flop Threading (Freewheel & Fixed), Single Speed Racing Front Rear Wheels For Track Bike, 2 Sealed Bearing(Silver)
Santafixie 700C 30 mm Rear Wheel – CNC Track – Single Speed – Flip-Flop Hub – Aluminium + 700x25C Tyre + Inner Tube (Black)
700C Fixed Gear Wheelset Bolt on Hub 9.5X100mm/9.5X120mm Solid Axle, Flip-Flop Threading (Freewheel & Fixed), Single Speed Racing Wheels for Track Bike, 2 Sealed Bearing,Colorful
Santafixie 700C 30 mm Wheelset – CNC Track – Single Speed – Flip-Flop Hub – Aluminium (Black)
