Retrospec Bicycles Fixed-Gear Crank Single-Speed Road Bicycle Forged Crankset Burly and lightweight three-piece forged crankset for ultimate strength and reliability 170mm crank arm length without any overlap of crank arm and chainring bolt All new crank arm designmuch stronger for faster and more aggressive riding Fits on road, mountain, fixed-gear, BMX, track, and single-speed bikes Standard Bolt Circle Diameter (BCD): 133