Elevate your game with the next-generation performance of the 509 Altitude 2.0 Offroad Helmet featuring the latest in weight-saving design and breathable comfort. Trail or track, the Altitude’s bestselling package twists the throttle wide open on airflow with a 40% larger chin bar intake and rear exhaust vents to keep you cool no matter what. Top of the line in every way, it includes the Fidlock® magnetic strap buckle for easy one-handed operation, plus GoPro® mounting capability.
You're going to LOVE the fit. Try it on and experience our perfect fit. If you don't love it, send it back in new and unused condition within 30 days for an exchange or full refund*. Risk free.
Not sure about your size? Try on at your local dealer!
*Street Helmets are a tighter fit due to cheekpad compression, however, they do pack out over time/use.
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.
Scroll to the right to see more sizes
| 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.
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.
Overall rating: 4.8297873 / 5 from 47 reviews.
The Altitude 2.0 Offroad Helmet offers excellent fit and fantastic quality, ensuring comfort and visibility for offroad adventures.
Review topics: ["fit","size","weight","price","quality","looks","color","works","helmet","air flow","system","light"].
"Top shelf stuff!"
"Great light helmet one handed chin buckle fits great…price was right!"
"Wouldn’t ever get a helmet without the Fidlock again! So lightweight and the sizing is super accurate."
"Took a good fall and man this helmet did its job ! Amazing looks and the science to back up its Saftey"
"Visor screws are weak sauce. One broke before I got to used the helmet."
"Helmet looks great and fits great. Got lots of compliments at my MSF course. Gets plenty of air flow on hot days. Carrying bag is very nice."
"Love this product"
"I needed a lightweight, 4XL helmet for riding my 4 wheeler. The Altitude 2.0 fit that bill perfectly. Paired with the Aviator 2.0 goggles, it's very comfortable even in rough dune conditions."
"All day ride in 90-degree heat. Stayed cool with plenty of air flow. Love it!"
"Love our 509 kits"
