• Measure your head circumference in centimeters approx. 2.5 cm above the eyebrows.
  • Divide the measured value in "cm" by a factor of 2.54 and find the obtained value in "inches" in the table of the appropriate helmet sizes.
  • If you are between two sizes, choose a smaller rather than a larger helmet size.
  • The helmet must be firmly attached and close to the head. If your helmet is too loose, you have the wrong size.

Instructions video:

Riddell size chart:

Riddell SpeedFlex Diamond size chart: