Helmet Size & Fit Guide

To find the right bike helmet size, measure your head circumference roughly 1 inch (or two finger-widths) above your eyebrows using a flexible tape measure, typically ranging from 51–63cm (Small to Large) for adults. A properly fitted helmet should sit level, feel snug but comfortable, and not rock more than an inch in any direction. 

Bike Helmet Size Chart (General Guide)

• Small (S): 51–55 cm / 20–21.75 inches
• Medium (M): 55–59 cm / 21.75–23.25 inches
• Large (L): 59–63 cm / 23.25–24.75 inches
• Extra Large (XL): 61–65 cm / Over 24.75 inches 

How to Measure for a Helmet

• Measure: Use a soft tape measure or string to wrap around the largest part of your head, just above your eyebrows and ears.
• Verify: If using string, measure the string length against a ruler.
• Check Size: Compare your measurement in centimeters to the manufacturer’s sizing chart, as brands can vary. 

How to Achieve a Proper Fit

• Position: The helmet should sit low on the forehead, about 1–2 finger widths above the eyebrows.
• Stability: When buckled, the helmet should not rock forward, backward, or side-to-side.
• Straps: Adjust the side straps to form a "V" shape just below the ears.
• Chin Strap: Tighten the chin strap so no more than one or two fingers fit between it and your chin.
• Retention System: Use the rear dial (if equipped) to tighten the helmet until it is snug but does not create pressure points. 

Signs of a Poor Fit

• Too Small: The helmet sits too high on the head or causes headaches.
• Too Large: The helmet rocks around or feels unstable.
• Incorrect Positioning: The forehead is exposed or the helmet covers the eyes.