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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Key Features
Aerodynamic
Aerodynamic design with durable ABS construction
Maximized field of view
Face shield designed for a maximized field of view with mirrored and tinted shield options
Venturi Venting
Innovative Venturi Venting System pulls moist air out without cold wind coming in Venturi Vents
Fidlock® Magnetic Chin Strap
Comes standard with Fidlock® easy-open magnetic strap clasp
Shuttered Venting
Adjustable shuttered venting at key areas of helmet shell
Drag
With a maximized field of view and high-flow Venturi duct venting, the 509 Mach V Helmet sets the stage for the next evolution in moto helmets. Whether you’re splitting lanes on the freeway or zoned in on the zen of riding, this sleek, stylish DOT and ECE 22.06 certified helmet with an easy gloves-on access Fidlock® chinstrap has been built for adrenaline junkies and city weavers alike.
Key Features
- Injection Molded Polycarbonate Shell - Built for performance combining durability and minimal weight
- Innovative Ventilation - Featuring 509’s Venturi Venting system that passively wicks sweat and moisture away.Three (3) intake vents and two (2) exhaust vents for optimal airflow → Learn More
- Dual pane shield for fog-free performance with new shield locks that create the perfect seal
- Multiple shield options available → Shop Shields
- Built-in breath deflector
- Rear reflective hits for low light and night riding
- ITO (Indium Tin Oxide) shield coating to prevent surface scratches and fogging
- 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
- App-driven customization, software, and feature updates for Apple and Android
- WARNING for California Residents
Specs
- Helmet Certifications: DOT & ECE 22.06
- Starting weight: 1750g
- Helmet Size Range: XS - 2X (Intermediate oval fit)
- Helmet Shell Breaks:
Medium Shell - SM, MD
Large Shell - LG, XL, 2X - Included Items: 509 Helmet Drawstring Bag and USB C charging cord (wall block not included)
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.
