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Smith Mainline full-face helmet review

Safety and comfort for a cool and protected head

Our rating 
4.5 out of 5 star rating 4.5
GBP £275.00 RRP | USD $300.00 | EUR €300.00
Smith Mainline full-face mountain biking helmet

Our review

The Mainline offers plenty of safety features, a great fit and decent venting – I'm a big fan
Pros: Solid design with plenty of safety features built in; comfortable; vents well
Cons: Not as light as the TLD Stage, but that doesn’t detract from the comfort
Skip to view product specifications

Smith’s long-awaited Mainline helmet joins an ever-growing market of low-weight full-face lids, designed for those looking for some extra protection while trail riding or enduro racing.


Just like Troy Lee Designs’ Stage helmet, the Mainline is downhill certified and can be used for multiple disciplines, which does make that price tag look more appealing.

It’s heavier than the Stage, at 830g in medium (the TLD weighs 697g), but does come with more safety features.

The Mainline’s Aerocore construction incorporates sections of Koroyd (the honeycomb-like structure that’s visible in places), which is said to help absorb impact force. Not all of the vents are covered with this, though, including the brow ports, a long intake across the top of the head and a rear exhaust vent, to help keep air moving through the lid.

Smith has also included a MIPS liner, which is claimed to help protect your brain from angular impacts.

There are three sizes to choose from (small to large). As on the Stage or Fox’s Proframe, there’s no adjustable cradle to tighten it onto your head. Instead, just like a traditional downhill full-face, the Mainline relies on you using different size pads to create an accurate fit (assuming you’ve got the right shell size).

Smith supplies the lid with three thicknesses of cheek pad, two crown liners and two neck rolls, so this is easy enough to achieve. To keep the lid properly secure, it’s opted for a double D-ring closure over the on-trend magnetic FidLock buckle we see more frequently these days.

After playing around with different pad combinations, I got my Mainline to fit comfortably and really securely too. The D-ring closure may take longer to fasten than a regular clip or magnetic buckle, but it feels good and doesn’t dig into your neck. The strap is padded, which helps.

There’s enough peak adjustment that you can keep it pushed up out of sight while you’re riding, too.

Thanks to the open vents around the chin bar, the Mainline never feels claustrophobic when you’re breathing hard, and on cooler days I didn’t bother removing it when tackling climbs.

The vents across the top and those nifty brow ports do a good job of channelling air in and over your head as the pace increases, so even on longer, flatter trails where you’re really having to pedal, I never felt like I was overheating.

Although the Mainline weighs a touch more than my go-to helmet, the Stage, this doesn’t seem to detract from comfort, even when worn for lengthy periods of time.


The solid fit and weight actually help to make your head feel really well protected, which is always good for peace of mind.

Product Specifications


Price EUR €300.00GBP £275.00USD $300.00
Weight 830g (M) – as tested
Brand Smith optics


Features Sizes: , M, L
Vents: 21
Visor: Adjustable
Colours: Black, AC | Rocky Mountain Enduro
Helmet type Mountain bike full-face