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The Mainline is Smiths' first entry into the full face helmet market. While it is expensive, it can definitely earn its keep – it’s supremely comfortable and it fits the bill for an enduro-focused full face almost perfectly. It has both the MIPS and Koroyd rotational-impact protection systems for impressive safety, though the Koroyd blocks some airflow.

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Alongside a rather nice drawstring bag to carry the hat in, Smith supplies a bunch of different cheek pads, two neck rolls and two crown liners. All this makes the size of the helmet almost completely customizable. There's also some spare visor hardware – handy.

Having had issues with the shape of other helmets, I’m a big fan of the inclusion of all of these pads.

You get an adjustable visor with a respectable amount of travel, a D-ring fastener, MIPS paired with Koroyd and EN 1078, CPSC 1203, ASTM F1952 certification. There are also 21 vents and a sneaky couple of extra vents underneath the brow.

All of that means the Mainline weighs 770g in the medium shell.

MIPS is the rotational impact reduction cradle we all know and love, while Koroyd promises to offer even more rotational impact protection. It's made up of a number of straws and can crumple under impact, but still allows air to enter the helmet in normal use.

The Mainline offers a potential level of protection not seen on helmets with only one or the other. It's almost more comfortable, too, as the MIPS cradle is a barrier to stop the straws rubbing your head badly.

The first thing you notice about the Mainline is how excellently comfortable it is. I didn’t have to swap the pads around either – it fits absolutely perfectly. It’s got a pretty big field of view, too, with the chin bar and visor being of minimal obstruction.

On the subject of the chin bar, it’s very well ventilated with the big open mouthpiece. You can easily thread the hose of your hydration pack through it and it doesn’t hold on to any exhaled air, so it never feels claustrophobic.

While I’m not usually a fan of Koroyd in helmets, here it allows the Mainline to have a very compact shell. Because of this, the helmet never feels cumbersome and you keep the full range of motion you usually get with open face.

However, the Koroyd blocks airflow. Granted, it's not blocked so badly on the Mainline as it is on other lids, but cooling would be a lot better without the straw-like lining in place. That said, it still cools pretty well.

While I was using it, it kept cool enough to keep it from getting overly sweaty, and the straws are directed well enough to keep some air circulating. It’s not as airy as something like the 100% Trajecta, but then the Mainline feels a lot more substantial and arguably offers more protection.

The Mainline is designed to integrate with the Smith Optics’ Squad line of goggles, but I used it with their Fuel V.2 goggles instead and it works absolutely fine. They fit well, and fogging is minimal.

While it's pricey, Smith Optics has done an excellent job with the Mainline. It’s thoughtfully ergonomic and super comfortable. The only real downsides are that it would be breezier if the Koroyd wasn’t there – if potentially less protective – and that some might prefer a Fidlock closure to D-rings. But that, really, is it.

• www.smithoptics.com

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