Once the reserve of downhill racers (or your friend with protective parents) the full face mountain bike helmet like this Smith Mainline is now a much more common sight in bike parks up and down the UK.
There are two reasons for this – firstly, smashing your face into the dirt really hurts, so a chinbar gives you a welcome layer of protection between the ground and your teeth. But the main reason, in my opinion, is that they’re just much nicer to wear now than they used to be.
Growing up in the 1990s, the full face lids we had access to were not exactly comfort focussed - more like an MX helmet than a MTB one. They were heavy and not particularly well ventilated – just about tolerable for a gravity ride but as soon as you needed to do any pedalling, forget it.
With races like the Enduro World Series not only requiring a full face to be worn on descents, but also on the way back up the hill too, manufacturers including Smith have reacted with lighter and airier designs like the Mainline.
Verdict: Despite the skeletal look and superb airflow, the Smith Mainline doesn’t skimp on safety, and is fully downhill certified to ASTM F1952 standard. It feels much more substantial than my old DH lid and although naturally a bit warmer on a climb than my Smith Forefront 2, the open sections on the chinbar and large vents up top do a great job of managing heat. It plays nicely with a pair of Smith goggles or sunglasses and is overall a joy to use.
What’s good?
The standout feature of this helmet for me is how little convincing I need before just putting it on and riding. I always find myself reaching for a full face lid on an uplift day (because no pedalling), but there are other situations where I’d like to have one, but then need to balance up the downsides of the extra weight and heat.
Often in those circumstances I would just make do with an open face helmet – but the Mainline is so comfortable it makes it an easy choice for any sort of riding where I might end up going full gas downhill, or trying a new line of jumps. There are much fewer downsides to wearing it than my old DH lid, so I might as well.
To quantify that a bit, the features I like most are the multiple vents on the top and rear, and the mostly open chinbar, which lets hot breath escape easily rather then building up inside the helmet. It also acts as a comfortable handle when holding it off the bike – sounds niche but my old lid was tricky to hold and as a result I’ve dropped it (only from about knee height, but still) several times.
Weighing in at just under 900g for this size large, it feels much lighter than those numbers suggest on my head. I think in part this is down to the superb tailored fit (which we’ll come back to) and the MIPs liner, which gives it a slightly floaty feel even when you’ve got the double D loop pulled tight.
Don’t get me wrong, it’s more than stable enough, but there are a couple of degrees of movement when you shake your head for example, which reduce how clamped down it feels overall. The theory here is that those degrees of movement also help protect your brain from rotational injury too.
Fit is easily tweaked thanks to interchangeable pads for your cheeks and the MIPs liner itself. It’s really easy to get it sitting just right, as these snap in and out with poppers.
Set up perfectly for me, I can feel a slight pressure on the base of my jawbone, but it’s reassuring rather than uncomfortable. The chinbar extends a decent distance out front too, so it doesn’t rub against my face or nose. Overall coverage is excellent, extending a good way down the back of my head.
Away from these subjective features, the Mainline has an undeniably expensive feel, whether it’s the tight shutlines between its various panels or the materials used, which are plush where they need to be and durable where they don’t. I also think it looks very cool, which shouldn’t be a consideration for a safety device, but let’s face it, it is.
The peak has a lot of adjustment and is held in place with breakaway fasteners. These don’t look as nice as the metal hex bolts on my Forefront 2, but I’d rather them function as intended and save my from a neck or brain from injury, due to the peak (which is quite large) not detaching on impact.
Cutaways in the EPS liner around the ears means you can wear sunglasses comfortably underneath this helmet, but if that’s a bit of a dorky look for you, Smith also sells a large range of, frankly, sublime goggles that integrate neatly with the Mainline.
I tested a pair of Squad goggles in the very steezy Sedona colourway, which isn’t an obvious colour match to the helmet, but I think they look mega. You get a mirrored, contrast boosting Chromapop lens, and a clear one for cloudier days, and they are comfy, superbly ventilated, and resist fogging too.
The shape of the Squad goggles fits perfectly in the helmet aperture – there’s not annoying overlap or pressure from the lid squashing them onto your nose. A no brainer add on if you're buying a Mainline.
They also “dock” really neatly on the back of the helmet, but just bear in mind this will block the vents and reduce airflow. As with other Smith products I've tested, both the helmet and goggles come with a soft protective bag to keep them safe on the back seat of your car.
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What’s okay?
What I will say is that while they integrate nicely when you’re wearing the helmet on your head, as soon as you take it off, they slide inside the aperture. On my old lid the goggles filled the aperture completely, right into the corners, and stayed in place even when I took it off my head. I think a larger pair of Squad XL goggles might solve this problem, but in all honesty it’s not really an issue, just a preference.
I haven’t mentioned the Koroyd layer on this helmet yet, which is the drinking-straw-like structure you can see here. It’s designed to deform in a crash like a crumple zone, and it’s part of what makes this helmet feel so reassuringly safe.
As with my Forefront 2, although it lets a breeze in and out, it will naturally reduce the volume of fresh air the vent can shift, due to its directional nature. I’ll take that compromise, though.
Any negatives?
It’s not cheap by any means - in fact I've spent less on motorbike helmets - but the fact you’ll reach for it time and time again means it’s much better value for money than an older, hotter full face lid. Other reviews reported the MIPs liner creaking – either Smith have fixed this or my big head dampens the noise, because it’s not a problem here.
How the product was tested
I’ve been riding in the Smith Forefront 2 for five months, including late summer, autumn and winter, so I’ve experienced lots of sun, downpours and freezing winds too. It’s been out at BikePark Wales, as well as my local bike park and Twisted Oaks, both of which are pedal-up.