509 Mach III Carbon Helmet Review [Dual Certification]

May 24, 2023

509 is a Polaris Industries aftermarket brand that has focused on snowmobile and off-road/trail-oriented gear. 509 has now expanded into street motorcycle products. We have already reviewed the 509 @One leather jacket. Now, we have tested the flagship offering in the new Street lineup—the Mach III Carbon full-face helmet.

The 509 Mach III Carbon helmet has a carbon fiber and fiberglass composite shell construction. With the Blacktop colorway and the clear gel surface that reveals the weave of that carbon fiber shell, the manufacturing quality is clear and visible. The payoff of carbon fiber is light weight and great strength.

The Mach III design delivers safety along with its featherweight construction. Weighing in at three pounds even on our scales, it is exceptionally light for an XL full-face helmet. On the technical side, it also delivers America's DOT FMVSS 218 and Europe's ECE 22.05 certifications.

That light weight pays off in low-fatigue, all-day wearability. The smooth, aerodynamic shape slips through the turbulence that a shorty windshield or speeds generate, making the 509 Mach III an excellent helmet for touring or track days.

Interior climate control is accomplished via dual closable chin bar vents and dual closable vents above the eyeport. The slide-activated vents can be opened and closed with gloves on. However, thick gloves require developing a feel for the vent shutters, as the tabs on each shutter are very low-profile. The six exhaust vents are fixed open.

In use, there are no whistling or buzzing noises. Located directly above the eyeport, the vents admit perceptible airflow to the forehead area and back on the skull. The vent location also means that airflow is reduced if the shield is in a raised position. With the vents closed, there is no perceptible stray airflow into the 509 Mach III.

The clear polycarbonate faceshield locks down tight over a neoprene edge gasket. The shield has a large lift tab attached to the lower left edge, with a small hook that engages securely into the chin bar. While the lift tab is large enough to be easily operated with gloves on, the hook means business, so disengaging it takes some effort. Once unlocked, the faceshield lifts easily and stays where you place it. Although there is no internal sunshield, there are four tinted and reflective shield options from 509.

There are four detent positions in the shield hinge system, with the lowest providing a clever area of higher resistance to shield movement. This allows placing the faceshield in a non-locked "demist" opening position ranging from just above the locked-down position to three-quarters-of-an-inch open. The shield remains in whatever position you choose, even in the wind.

Closing and locking the shield on the 509 Mach III helmet proves to be a two-handed operation. Lowering the shield to the stop puts it in the slightly open position. That's fine for me, as it tends to be the position I prefer. However, I could not get it to the fully locked-down position with just one hand on the large tab.

Pushing down on the tab causes the shield to flex inward slightly, causing the bottom edge of the shield's hook to be blocked by the top edge of the hook slot. Pulling outward on the tab while pressing down didn't work, either. To get the tab to allow the shield to reach the locked-down position, applying pressure downward at the top right edge of the shield while pushing down on the tab is necessary. That makes getting the shield to the lock-down position a two-handed operation.

A metallic button in the center of each hinge is pressed to unlock the faceshield for removal. Installation is performed by simply pressing the shield into the hinge, with the tabs on the inside of the shield aligned with the slots in the hinge base and the shield in the raised position.

There is no chin curtain on the 509 Mach III helmet; that allows significant air up-flow to the rider's face. That, in combination with the chin bar vents in the open position and the shield in a slightly open position, prevents shield fogging. Surprisingly, there isn't a perceptible increase in wind noise over most helmets I’ve used that have a chin curtain.

Perhaps the most interesting innovation in the 509 Mach III helmet line is using a Fidlock magnetic chin strap buckle. A magnetic hasp causes the catch to snap together—say goodbye to the old double-D ring buckle.

While the Fidlock is a welcome change from the old two-hands-required D-rings and quite simple to use, its operation takes some practice. Unfortunately, the process is poorly illustrated in the owner's manual, but I can explain it.

Unbuckling the strap is a one-hand, pull-the-red-tab-and-its-open operation, with closing the buckle a bit more involved.

To close the buckle, a rectangular metal ring must drop into position behind a keeper made of Grivory or Durethan. Then, the magnetic locking tab swings into position on the keeper to close the buckle.

Initially, I struggled to align the space in the metal ring with the keeper. I concluded there was no way to get this thing closed with gloves on. After some experimentation, I discovered the technique.

Grasp the red tab used to unbuckle the strap and pull it up to the keeper side. When aligned properly, the magnet usually snaps the buckle closed by itself. Getting the routine down takes a little practice, but it works. After you hear the buckle snap shut, give the strap a stout pull to verify it is securely locked. You’re all set!

There is no strap-end retainer snap or hook-and-loop provided, so when you adjust the strap to fit, if you need to snug it up quite a bit, you end up with that loose strap end hanging out. It ends up flying around in the breeze, which may be bothersome to some riders. In my case, I just slipped the excess strap back over the strap itself, reducing the problem.

The polyester mesh comfort liner is well-padded and removable for laundering. The instructions in the owner's manual for removing and installing the liner are sketchy, at best.

The 509 Mach III helmet comes with a luggage-quality, padded, ventilated nylon logo-imprinted carrying bag, along with a typical cloth bag with a drawstring closure. The carrying bag is large enough to accommodate your riding gloves and other small items, as well as the helmet. The carrying bag also has a large, external mesh pocket on the end and a full-length zippered pocket on the side.

If there is anything that's something of a disappointment with the Mach III, it is the owner's manual. It is missing basic user information on several operation items. For example, the diagram on how to use the Fidlock buckle is difficult to see and interpret. Instructions on how to change the shield are sketchy, at best. Having done shield changes many times, I worked it out fairly quickly, but new riders unfamiliar with hinge systems may have difficulty. Also, the manual is difficult to read, as it uses tiny, somewhat faint print.

References to avoiding frostbite make me wonder if the manual was produced using a previous snow helmet manual as the basis, as it seems to only have a vague connection to the features and operation of the Mach III product. There is good general content about helmet do-and don't items, but not much that is direct how-to information on this specific helmet.

Two colorways are available— Blacktop, which is essentially the gray/black woven surface of the carbon fiber shell with a clear gel coat over the top and a fine, gray pinstripe graphic, and Zenith, which shows the same carbon fiber view around the chin bar and sweeps up at an angle around the back of the helmet, while the rest of the helmet shell is white.

The 509 Mach III Carbon features excellent fit, finish, and appearance. I like the innovative thinking with the Fidlock chinstrap buckle. It is lightweight, comfortable, and has high-level protective credentials. These all come at a $400 price point—impressive for a carbon fiber helmet. It's a great bit of kit from 509 as it expands from the snow and off-road scene into the street.

509 Mach III Carbon Helmet Fast Facts

509 Mach III Carbon Helmet Price: $400 MSRP