Surly track cogs are threaded the same as a BMX freewheel (1.375 x 24 tpi right-hand threads). This means that they will thread onto single-speed rear hubs, as well as BMX freewheel hubs, *but will will be unsafe to ride*. Track cogs are meant to work on track hubs when secured by a locking only.

• 415 hardened chromoly steel
• 1.375" x 24 tpi
• Photo for color and material reference only