Smith Mainline Review: The Best Full Face Helmet For Mountain Bikers?

A helmet can look great and be super comfortable to wear, but what matters the most is its safety. It’s gotta keep your head intact if and when you go OTB, right? Here are the main safety and performance features of the Smith Mainline:

The Smith Mainline is one of the safest full face mountain bike helmets out there. It’s been approved for a few safety ratings including:

• ASTM F1952 Downhill Standard approval rating, the highest safety rating for mountain bike helmets.
• CPSC CE EN 1078, a Consumer Product Safety Commission safety approval for bicycle helmets.
• NTA-8776, a safety approval for e-bike use.

In short, the Smith Mainline has been put through rigorous testing to ensure your noggin is protected during a high-speed crash.

This helmet also utilizes MIPS Technology, which most mountain bike helmets these days should come with. MIPS stands for Multi-Directional Impact Protection System. This means that MIPS helmets – including the Smith Mainline – have a thin, plastic liner that is designed to protect your head against rotational forces during a crash.

You can learn more about how the technology works on the MIPS Protection website.

In addition to Mips, the Smith Mainline also uses KOROYD technology. This lightweight material is formed into a proprietary honeycomb design. It has two main functions: to enhance impact protection while maintaining optimal ventilation and lightweight construction.

In theory, this unique KOROYD technology is engineered to absorb and dissipate energy upon impact, thus reducing the forces transmitted to you – the rider’s – head.

I also think it looks cool!

A full face helmet should protect your full face, right? The Smith Mainline has great coverage from the back of the head to your pearly whites. It provides protection of your face, jaw, and chin without feeling like you’re locked in a cage.

I also appreciate the large cut-out in front of the mouth area. This helps reduce fogging and makes it easier to talk to your friends.

The Smith Mainline has an adjustable visor, however, unlike most ‘normal’ mountain bike helmets, this one requires you to manually adjust it with a dial. This is just another safety feature built into the Smith Mainline. The dial prevents the visor from slipping down or getting caught in a gust of wind as you’re bombing downhill.

True to downhill full face helmets, the Smith Mainline has a D-ring fastener as a chin strap. It’s not quite as easy to use as the magnetic fastener many mountain bike helmets come with these days (like the Bell Super DH), but this type of fastener is safer because it won’t inadvertently come undone during a crash.

I’d gave it 4/5 starts because it’s a little annoying to fasten and unfasten, especially with gloves on, but I guess that’s a small price to pay for safety.

A mountain bike helmet has to be safe, but it also has to be comfortable, right? Full face helmets might not be the most cushy thing in the world to wear on your head, but here’s how Smith has designed the Mainline to be tolerable:

For a full face helmet, the Smith Mainline is pretty darn comfortable. The crown is lined with nice padding that is removable so you can rinse it out after a few bike park days. It also has thick cheek pads and a neck pad for extra cushioning (both of these are removable as well) as well as padding under the chin strap, which is a nice touch.

I also love that the Mainline is quite lightweight for what it is. It doesn’t feel like you’re wearing a bucket on your head – instead, it feels like you’re wearing a helmet that was designed to be both comfortable and protective.

The Smith Mainline comes in three different sizes: small, medium, and large. You can use their size chart below to determine which size you are.

This helmet also comes with three different cheek pad sizes and two neck liner pad sizes so you can get a snug fit. It is a bit of a waste to have extra sets of pads you won’t use, though…

The reason I give the Smith Mainline only four stars for fit is because it doesn’t have a fit dial at the back of the head like most mountain bike helmets do. I’m not sure if this has to do with safety (a dial could come loose during a crash I suppose) or something else, but it is a feature I miss. I often catch myself reaching to the back of my head to snug up my helmet a bit only to remember that the Mainline doesn’t have a fit dial.

It feels weird to give a full face helmet 5/5 stars for ventilation, but the Smith Mainline deserves it! I don’t know if it’s the honeycomb KOROYD design or the 21 vents that promote good airflow, but the Mainline doesn’t feel stuffy or like a sweatbox.

Of course, the ventilation isn’t going to be as good as a ‘half lid’, but for a full face it’s pretty darn good.

🪖 Additional Features

The Smith Mainline has a few other features that are worth mentioning. They include:

⚖️ How it Compares

Not yet sold on the Smith Mainline? Here’s how it compares to three other popular downhill full face helmets: The Troy Lee Designs Stage, the Fox Proframe, and the POC Coron. Honestly, the main differences between these three helmets are the weight, price, and chin strap fasteners.