How to Measure
When measuring your head, use a cloth tape. Start it just above your eyebrows and circle it around the thickest point in the rear of your head and then reference the size guide below.
509 Helmet Size Chart
| Size | US Hat Size | Inches | Centimeters |
|
X-Small |
6 5/8 - 6 3/4 |
20 7/8 - 21 1/8 |
53 - 54 |
|
Small |
6 7/8 - 7 |
21 5/8 - 21 7/8 |
55 - 56 |
|
Medium |
7 1/8 - 7 1/4 |
22 1/2 - 22 5/8 |
57 - 58 |
|
Large |
7 3/8 - 7 1/2 |
23 1/4 - 23 1/2 |
59 - 60 |
|
X-Large |
7 5/8 - 7 3/4 |
24 - 24 1/4 |
61 - 62 |
|
2X-Large |
8 |
24 3/4 - 25 |
63 - 64 |
|
3X-Large |
8 3/4 |
25 1/4 - 25 3/4 |
64 - 65 |
|
4X-Large |
9 |
26 - 26 1/4 |
66 - 67 |
|
Youth Small |
6 |
18 1/8 - 18 7/8 |
47 - 48 |
|
Youth Medium |
6 1/8 - 6 1/4 |
19 1/4 - 19 5/8 |
49 - 50 |
|
Youth Large |
6 3/8 - 6 1/2 |
20 - 20 1/2 |
51 - 52 |
Pressure Points
When trying on a helmet, take note of any pressure points on your forehead—a sign that the helmet is too round. Pressure points on the sides of your head indicate a helmet is too oval for the shape of your head. After you buy a new helmet, try wearing it for 30 to 45 minutes to check for pressure points before using it on a ride.