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.
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Reinvented to ride even harder, the second generation of the bestselling 509 Altitude series unleashes a whole new animal. For those who run at redline, the new 509 Altitude 2.0 Carbon Fiber 3K Hi-Flow Helmet maximizes airflow with open upper and rear vents plus a 40% larger chinbar intake. Everything else is what you’d expect from one of the world’s bestsellers, including a new hand lay-up carbon composite construction that makes this helmet lighter, stronger, and even more comfortable.
Key Features
- Hand lay-up carbon fiber 3K Shell
- Upper vents for airflow control (shutter closure not available on Storm Chaser and Cyan Navy colors)
- Hi-Flow venting technology allowing more airflow through a 40% larger chinbar intake
- Upper vents with on/off shutter closure for airflow control
- Nine intake vents and four exhaust vents for optimal airflow
- Fidlock® The Fidlock System is a cutting-edge magnetic chinstrap buckle used in motorsport helmets ensuring quick, secure, closures with one hand and is DOT and ECE compliant.chinstrap strap closure for easy in and out
- Moisture wicking removable Liner & Cheek pads for custom fit adjustments and easy to wash → Shop Cheek Pad for Altitude 2.0 Helmet
- Pro-Series Breathbox for complete protection, removable for optimal air flow
- Replaceable polycarbonate visor with Lifetime Warranty
- Universal camera mount capable
- WARNING for California Residents
Specs
- Helmet Certification: ECE 22.05
- Starting Weight: 1,050 grams
- Best Head Shape: Intermediate oval fit
- Size Range: XS - 4X
- Shell Breaks:
Small Shell - XS, SM
Medium Shell - MD, LG, XL
2X Shell - 2X, 3X, 4X - Included items: 509 helmet drawstring bag, 509 helmet bag, Pro-Series breathbox, 509 Sticker
Size Guide
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.
