Chainrings & Bolts

When buying chainrings you need to know the BCD aka  Bolt Circle Diameter. This is the measurement of an imaginary circle on the chainring hitting all the bolt holes. The best way to calculate this is by measuring the exact distance (center to center) between 2 neighbouring bolt holes. Then find that number on the correct chart below to determine the BCD for your chainring and cranks...

BCD chart for 5-bolt chainrings
Bolt to Bolt (measure center to center) BCD Bolt Circle Diameter 
32.9mm 56mm
34.3mm 58mm
43.5mm 74mm
55.4mm 94mm
64.7mm 110mm
76.4mm 130mm
79.5mm 135mm
84.6mm 144mm
 
BCD chart for 4-bolt chainring
Bolt to Bolt (measure center to center) BCD Bolt Circle Diameter 
41mm 58mm
45.3mm 64mm
48.1mm 68mm
73.6mm 104mm
79.2mm 112mm

Choose your ring size below...