Number of Teeth (Chordal Action)Nom. Pitch DiameterNom. Outer Diameter Nom. Hub Width Available Bore Sizes
inmminmminmmRound in1Square inRound mm1Square mm
8 (7.61%) square bore5.21325.31351.538 1.5 40
8 (7.61%) round bore5.21325.31351.2301-1/4
10 (4.89%)6.51656.71701.5381-1/41.5 40
12 (3.41%)7.71968.02031.5381-1/41.5 40
  1. Imperial key sizes on round bore sprockets are based on ANSI standard B17.1-1967 (R1989) and metric key sizes are based on DIN standard 6885.