Smith’s First Full-Face MTB Helmet, the Mainline, is a Winner [Review]

For having one of the most seen mountain bike helmets on the trails – at least in my anecdotal calculation – Smith has taken their sweet time developing a helmet with stronger gravity intentions.

The Forefront, followed by the Forefront 2 are popular mountain bike helmets indeed. Though pricey for a half-shell helmet, I’ve seen many on them on my local trails over the years, donned by enduro-ers and aggressive trail riders. The Forefront is lightweight, with large, open vents, and an overlapping insurance policy with both MIPS and Koroyd.

MIPS is basically a slip-plane, deflecting the energy from oblique impacts, but Koroyd also helps displace rotational energy, while acting as sort of a crumple zone.

While Giro, Fox, Leatt and others have been pushing their enduro, gravity, and convertible helmets, Smith loyalists finally have a full face option for the bike park or for enduro-ing.

“Designed for the elite level user, Smith’s team of product designers and engineers spent two years developing the pinnacle product with informed insights from notable Rocky Mountain Enduro athletes Remi Gavin, Andreane Lanthier Nadeau, and Jesse Melamed. The Smith-sponsored team was crucial in formulating and refining the construction, design, features and aesthetics of the DH-certified (ASTM F1952) enduro helmet.”

The new Smith Mainline has a lightweight in-mold construction with complete Koroyd coverage for a stronger skeletal structure with better ventilation. Smith adds that the MIPS lining reduces rotational forces. The Mainline has a total of 21 vents with internal air channels which combine with intake and exhaust ports for optimized ventilation, even when wearing goggles.

The Mainline also includes three sets of cheek pads — small, medium, and large — and two sets of crown liners in different sizes. The Mainline uses a D-ring chinstrap fastener and it comes in at a light 800g. All that protection technology in a lightweight package with the Smith name rings in at $300. (Available online at Competitive Cyclist, REI, and evo.)

On the trail

A little more confidence for bigger features. Photo: Hannah Morvay

I have yet to make it to a bike park this season. Only one in my more immediate area is actually open at the moment, and I have been spending more of my time on backcountry rides, since the one bike park that has been open looks like it’s been slammed with people.

The visor has about a half-inch of travel, clamped into place with a turn dial.

I rarely ever ride singletrack with a full-face helmet, but with some gnarlier, bike-optimized riding available close to home at Floyd Hill, I took the Mainline there, strapped up, and started climbing.

And, I was impressed. I swung these Smith Squad XL MTB goggles around to the back with the strap on the brow of the helmet, and I wasn’t more bothered than I would have been climbing with a half-shell. That’s not to say that it’s not going to get more hot than a half-shell, especially on warmer days on an exposed trail. Light breezes can be felt through the helmet’s intake vents.

It might take a little bit of target practice, but it’s not impossible to to quench your thirst with the helmet on. Photo: Hannah Morvay

Smith classifies the Mainline as an enduro helmet, and with the Rocky Mountain Race Face enduro crew marketing the full-face, it likely means that a lot of other enduro riders will also be wearing it uphill, and eventually, they’ll get thirsty. The large, open vent in the front of the chin bar makes it easier to get a hydration tube through, or squirt a bottle into.

Once you’re pointed downhill, the helmet is forgettable. There’s an added confidence from the ASTM F1952 DH-certification, and with more wind flow, my sweaty head began to dry out quickly.

The cheek pads that came in the helmet were a little too tight for me, but since there are two other sets included, I swapped to a thinner set, and they worked great.

I also tested the Smith Squad XL ChromoPop goggles. The lenses have a red tint, which reduced highlights and bright spots on the trail, making greens very vivid. The Squad XLs gave me a clear advantage when it came to recognizing terrain, and they were lightweight and fairly well vented.

Closing thoughts

Photo: Hannah Morvay

The Mainline is light, breathable, and it looks great. The DH-certification and D-ring buckle add to the Mainline’s ruggedness, while the Koroyd-lined interior makes it easy to wear. Smith fans have long been waiting for a more serious mountain bike helmet, and this offering shouldn’t disappoint.

Thanks to Smith for providing the Mainline for review.

⭐️ Find the Smith Mainline helmet online at Competitive Cyclist, REI, and evo.

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