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.
Free US Shipping
We offer Free Shipping on all orders over $99 within the US. During select promotions & holidays we will offer Free Shipping on all orders within the US.
3 Year Warranty
We stand behind our products – with a 3 year warranty against materials and workmanship for all helmets.
100% Secure Checkout
At 509 we use the best SSL certificate and the most trusted payment processors provided by Shopify Payments.
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
- Maximized field of view
- Innovative Venturi Venting System pulls moist air out without cold wind coming in Venturi Vents (Manual shutter built into interior of helmet at chin bar to allow comfortable ride) → Learn More
- DOT and ECE 22.06 certified - global standard (EU and CA)
- Fidlock® chinstrap for easy on and off
- Injected molded construction for lightweight and durable performance
- Premium Liner for a comfortable and quiet fit
- Custom liner kits available for a custom-tuned fit → Shop Now
- Breath Deflector included
- WARNING for California residents
Specs
- Starting Weight: 1750 grams
- Head Shape: Intermediate Oval
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.
