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: 4.876289 / 5 from 97 reviews.
The Altitude 2.0 Carbon Fiber Helmet is praised for its lightweight design, stylish appearance, and comfortable fit. Customers appreciate its sleek look and the convenience of its magnetic strap, making it ideal for extreme activities.
Review topics: [fit, strap, weight, issues, quality, looks, color, works, design, comfort, finish, features, style, neck, protection, helmet, padding, light, goggles, combo, carbon fiber, head, lid, season, rides, stay, system, altitude 2.0, difference].
"This helmet is incredibly light and has great features. It also looks amazing!!"
"So happy with the helmet paired with the sinister goggles was an excellent choice, the attitude that the helmet gives off is more than ideal, can’t even tell it’s on your head it’s so light and gives you 45% more maneuverability than your regular helmet and perfect fit"
"Been running this helmet for years, super light and comfortable."
"I just bought my second of these helmets, they embody everything great about 509, lightweight, strong, safe, and very aesthetically pleasing. Can’t wait to put on my new one this year."
"Love how lite weight this helmet is fits great great fit with the 509 goggles as well"
"The Altitude 2. 0 Carbon is the best helmet I have every owned. The fidlock is my favorite feature allowing me to take my helmet off and put it back on in seconds. After taking a few tunnel strikes to the head I can attest that the carbon fiber is extremely tough yet so light that I do not have neck fatigue at the end of the day. This is a helmet that is worth the investment."
"Fit and finish on this helmet is amazing!"
"I’ve been using the Altitude 2. 0 Carbon Fiber Helmet for a few months now, and it’s easily one of the best helmets I’ve owned. The carbon fiber construction makes it incredibly strong while staying impressively lightweight, you really notice the difference on longer rides. The fit and finish are top-notch. The padding inside is plush but breathable, and the adjustable strap system ensures a snug, secure fit without any pressure points. Ventilation is excellent, I also appreciate the aerodynamic design and how quiet it feels at speed. From a safety standpoint, it inspires real confidence. The carbon shell feels rock-solid, and the overall build quality is premium. Plus, it just looks fantastic, sleek, modern, and clearly well-engineered. If you’re serious about performance and protection, the Altitude 2. 0 Carbon Fiber Helmet is a smart investment. It delivers the perfect balance of comfort, style, and safety. Highly recommended!"
"I love how light it weight. Fits good with the googles and is pretty warm and comfortable in the harsh cold environment I drive in. And the design of the helmet is looking good! I took the white and black one."
"Absolutely love my 509 Altitude 2. 0 Carbon Fiber Helmet. The first thing that stood out to me was the style — it just looks amazing. Every time I’m out riding, I get compliments on it. The sleek carbon fiber finish really turns heads. But beyond the looks, it’s the comfort that sealed the deal for me. It fits perfectly and feels super light — no more neck strain, even after long days on the sled. It’s one of those helmets you forget you're even wearing, which says a lot. 509 nailed it with this one — premium quality, great design, and all-day comfort. Would definitely recommend it to anyone looking to upgrade their gear."
