How to Choose the Best Mountain Bike Helmet

How to choose the best mountain bike helmet

Back in the day strapping a piece of foam to your head looked as bad as it sounds. While the picnic cooler liner has been the bicycle helmet’s mainstay of protecting power since the mid-80s, elements of comfort, convenience, and aesthetics have come so far that today’s MTB skid lids are now as much a fashion statement as a necessary evil.

Choosing the “best” mountain bike helmet is like choosing the best bike — all that really matters is that you have (and wear) one. That said, head shape, riding style, and personal preference means some helmets will be better than others.

“What should you consider when looking for the better helmet?” is the question I will address on the first page, with differences between genres and recommendations on following pages. Whether you’re budget-minded, bold, or baller, I’ve gathered some of the best offerings from a variety of helmet manufacturers. If yours isn’t listed, make a case for it in the comment section below.


Helmet Safety Standards

By law, every bicycle helmet sold in the United States since March 1999 must meet the Consumer Product Safety Commission (CPSC) minimum safety standard. Other certifying organizations have come and gone before 1999 and some (Snell, ASTM, CE) still exist, but are either voluntary stamps of approval or apply in specific applications. Denoting the US certification preference is important because, although the CPSC is widely used throughout the world, some countries have adopted their own standards.

Most standards follow a similar protocol. The helmet is secured to a headform that measures g-force (G) on impact after being dropped one to two meters onto an anvil. Permanent head injury occurs at 400 Gs while 300 Gs produces unconsciousness with possible neurologic sequelae. Helmet straps, amount of coverage, and stability when yanked are also tested.

Photo: Consumer Reports

Perhaps more valuable to the consumer is what a safety standard does not tell you. The CPSC and others set minimum requirements based on data gathered in a laboratory. While you may not suffer permanent brain damage with a helmet, most certifying agencies set the failure threshold at 300 Gs — a force, at the very least, likely to knock you unconscious! The standard also does not tell you how far it exceeds the minimum. Finally, a lab is not a trail and I don’t recall the last time I was able to predict a fall from the height, speed, and temperature onto the surface shape of my choosing.

The take home: no certified helmet can guarantee you won’t break yourself upon any impact.

What is MIPS?

From our MIPS primer, “MIPS is a thin layer of material that goes between your head and your helmet…allow[ing] your helmet to rotate on your head in an impact while still wearing it snugly in normal riding.” The slip plane concept makes sense in theory, but if not executed correctly, does no more than jack up the prices on helmets that are just as safe (and cheaper) without MIPS. Here is a more thorough background on MIPS and I’ve summarized the more salient points on why MIPS may be more fiction than fact.

Image: Scott Sports
  • The slip plane concept requires a full sliding layer that many companies are not employing correctly. The layer interface either doesn’t fully encompass the helmet or fails to provide the appropriate sliding material.
  • The scalp (especially coupled with hair, oil, and sweat) is Mother Nature’s MIPS.
  • Adding a layer for MIPS provokes companies to decrease the EPS liner, which is more important in mitigating head trauma.
  • Overall, there is limited research on MIPS.
  • Rounder, smoother helmets may be just as good as MIPS at providing a slip-able plane.

MIPS won’t make a helmet less safe, but don’t lose sleep if your next favorite helmet doesn’t have it.

Helmet Fit

When it comes to helmets, fit is synonymous with safety, but fit is not standardized under any test. It’s up to you to determine proper helmet fit. The shape of the mold is selected by individual helmet manufacturers, which is why some helmets fit you better than they fit me.

Here are some rules of thumb for fitting a half shell and full face mountain bike helmet:

  • The inside of the helmet should come in contact with your entire head and sit level, just above the brow, without interfering with vision.
  • The one-size-fits-many ring system should be tensioned enough that your scalp moves with the helmet.
  • More expensive helmets have two to three height adjustments for the rear stabilizer to further tune the fit.
  • Straps should be tight enough that the helmet moves no more than an inch from level.
  • Straps meet at a Y that is adjusted just below the ear.
  • When fastened, check the buckle’s strength by giving it a quick tug.
  • If the helmet moves more than an inch or slides over the scalp after the above steps, it may not work for your head.

Due to additional adjustability, finding the right half shell is not nearly as tricky as a full face, which depends on inner pads and a mold that best suits your head.

  • A properly-fitted full face should almost feel too snug. Don’t worry, that squishy foam padding will soon pack out to where it feels just right.
  • Make sure there are no voids between helmet and head.
  • Cheek pads should feel firm enough against your cheeks that you cannot fully puff them out and to the point it makes speaking a little more difficult.
  • With the chin strap fastened, grab the chin bar and rock the full face to and fro; your scalp should move with it.
  • If you plan on rocking a neck brace, take it along to assure compatibility.

Helmet Materials and Construction

Despite the variety of shapes, vent orientation, tensioning systems, and other features, nothing on your helmet is more important than the crushable foam liner sandwiched between the outer shell and your head. Liners are made from beads of expanded polystyrene (EPS) that spread the energy of an impact by deformation, bringing your head to a slower stop. EPS can be tuned to a density that fits the helmet’s application (softer for slow speed impacts and harder for high speed). Some companies employ multiple foam thicknesses to achieve the best of both.

Smith uses a meshwork of rubber straws they call Koroyd to enhance impact resistance. Image: Smith Optics

Without the outer shell we’d all look like we’re packing perishables to a picnic. Besides providing a more agreeable surface for pinstripes and decals, the outer shell protects the crushable liner and provides a smooth surface so the helmet slides along the trail instead of snagging. Entry-level helmets typically have plastic shells glued to the EPS, while higher-end lids bond the shell to the liner in-mold during polystyrene expansion.

iXS putting the X Matter where it matters, seen here in a cutout on the Xult full face

If your budget allows, in-molding is highly recommended for two important reasons. First, by nature of the process, in-mold requires a higher quality shell which better protects you and the EPS liner. Second, because the shell and liner essentially become one, dents are more visible to help you identify underlying cracks in the EPS that would otherwise be masked by dead space between two glued layers.

A new twist on rotational force reduction with Armourgel, used by Kali and the new Leatt Enduro 3.0. Image: KaliProtectives

Beyond the foam liner, straps, and ensuring a proper fit, every other helmet feature either provides more comfort or convenience. These features also happen to be the main reason why a helmet might cost $160 more than a helmet meeting the same CPSC standard. There is no shortage of bells and whistles here, so i’ll address some of the more common features.

Helmet Ventilation

Ventilation ports are strategically placed to draw air in and channel it to exit points, thus cooling by convection. Larger front vents are better at determining a helmet’s ability to cool. Given the density and thickness of the foam liner, the ability to protect your head is always at odds with keeping it cool. Increasing ventilation with either more or larger ports requires a denser foam or liner reinforcement which may actually transmit more g-force to the head on impact. In other words, more vents are not always better.

Image: Fox Racing

Many companies do a nice job explaining away their helmet’s cooling capabilities, but testing is difficult and subject to several limitations. Case in point, a change in head angle of just a few degrees makes a big difference in how air is channeled through vents. Other confounding factors include a proper fit, hair, and sweat.

Convenience Features

By now, you’ve whittled your helmet options to a fairly short list. Just to make matters more difficult, consider the frosting on the cake. While these features should fall low on the list of priorities, they can be the difference between a great helmet and one that is perfect!

  • Removable chin bar: the ability to transform a half shell into a full face is a good fit for those looking for an extra edge, peace of mind, or for those who can’t afford a dedicated DH lid. While a convertible full face does not replace the protecting prowess of the full-fledge full face, it gets pretty damn close, with some even passing ASTM certification.
  • Lens compatibility: Most DH helmets work well with most goggles, but half shell heights, straps, and occipital coverage can make a new helmet purchase turn into a new sunglasses purchase. Take your googles and/or shades along when shopping to make sure they play nice with the helmet(s) you’re considering.

  • Light compatibility: depending on how you rig your night light, take your mounts along to see which vent configuration works better.
  • Visor: inspect the visor and its attachment points for ease of use and potential durability issues. Lower end helmet visors snap into place using small plastic stems, while higher-end helmets offer tool-free screws for adjusting and removing.
  • POV camera mounts: some helmets come camera mount-ready, while most require your own modification. Like lights, if you insist on mounting your camera up top, make sure the helmet is amenable.

A note on aftermarket mounts: Helmets standards discourage anything protruding from the helmet due to risk of snagging. Please ensure that any modification such as a light or camera mount will break free under reasonable amounts of stress.

Bicycle Helmet Buying Tips

  • Due to the importance of getting the right fit, try before you buy if possible.
  • Never buy a used helmet. It’s not possible that the previous owner is aware of hidden micro fractures in the EPS liner.
  • Replace your helmet after a crash. Damage may not be visible to the naked eye, but it’s there.
  • Know your terrain and riding style. Get the right tool for the job.
  • Spend what you need to properly protect your brain. Despite safety and fit being the most important, you need to like it, too!

Recommended XC Mountain Bike Helmets

Not that there’s anything wrong with cross country helmets, but recent design changes in mountain bike-specific (trail) helmets have essentially relegated XC-style lids to the road. In fact, some helmet manufacturers don’t even list these lower profile lids under their mountain category. I would have avoided the XC category all together, except to make the distinction between these and the modern trail helmet.

Cross-country helmets typically weigh the least and ventilate the best, but offer less coverage than any other genre. Most notably, XC helmets offer less rear coverage, and vent ports are usually either massive or many. Visors are typically missing in the XC category in order to maximize front end air intake and cut down on weight. Do not mistake XC helmets as unusable for mountain applications — they’re fine, but they’re the bare minimum. As the list goes on, it will become apparent why subsequent genres are more capable for mountain biking demands.

Urge Supacross Helmet

  • Weight: ~230g
  • Vents: 12
  • MIPS: No
  • MSRP: $115

Urge Supacross mtb helmet

If you’re looking for a truly unique helmet, take a look at the entire Urge lineup. I reviewed the Supatrail helmet last year and, while I found it a little undergunned for big mountain, it and the Supacross would make a perfect XC lid.

Recommended Trail Mountain Bike Helmets

Call it what you want (trail, all-mountain, enduro), but these helmets are what the lion’s share of mountain bikers prefer. The most noticeable difference between trail and XC helmets is the extended rear and side coverage, adding safety to these vulnerable areas. More coverage means heavier and less breathable, but increasing the safety factor is a tradeoff most are willing to accept.

Trail helmets typically employ a visor, and you’ll want to pay attention to its adjustability and stability, especially if you need somewhere to park your goggles. Ventilation ports begin to shrink and become less in number, but again, coverage and safety precede weight where the risk of injury is greatly increased on the mountain.

POC Trabec Mountain Bike Helmet

Although POC was one of the earliest MIPS adopters, they haven’t skirted other safety elements that are just as important. The Trabec features a round, smooth, almost skate-style profile and well-faired vents that go a long way in mitigating rotational injury without the MIPS premium. To boot, POC somehow does this while maintaining a modern look.

Troy Lee Designs A2 MIPS Helmet

  • Weight: ~350g
  • Vents: 13
  • MIPS: Yes
  • MSRP: $169

Admittedly, I’m a fanboy of Troy Lee since purchasing my own A1 two years ago. After an exhausting search, I found the comfort and fit unbeatable. The A2 offers a bit more ventilation than the A1 helmet.

iXS Trail RS Helmet

Remember that time I said the TLD A1 was unbeatable in regards to comfort and fit? Well, most of the exhaustion was choosing between it and my runner up, the Trail RS from iXS. The new EVO version has enhanced adjustments and comes in four sizes (XS-XLWide), making it easier to find that perfect fit.

Smith Forefront Mountain Bike Helmet

  • Weight: ~285g
  • MSRP: $220

You either love it or hate it: the Smith Forefront. In terms of looks, I fall in the former group. In Aaron’s Smith Forefront review, he praised the helmet for fitting his oversized noodle. Bro, do you even Koroyd?

Giro Hex Helmet

The Giro Hex mountain bike helmet offers some important high-end features such as an in-molded EPS liner and polycarbonate shell, all in a price-conscious package. Vent ports are strategically angled and the visor squared, creating a bold, muscular style. It doesn’t look like a sub-$100 helmet, but that’ll be your dirty little secret.

  • Weight: ~305g
  • MSRP: $80

Recommended Convertible Full Face/Enduro Mountain Bike Helmets

Recently some helmet companies have taken in the rebirth of the convertible full face mountain bike helmet. Traditional full face helmets are unmatched in protective prowess, but they turn into a sauna on any trail not pointed down. On the other hand, a more breathable half shell may leave you feeling a little naked when raging from peak to creek. The convertible full face is like the 27.5″ wheel of helmets, allowing riders to take advantage of both trail lids and traditional full facers.

Having a removable chin bar has become increasingly popular for enduro racing, which involves steep, technical descents with a significant amount of time climbing between stages. It may also be a viable solution for those on the fence about a traditional full face due to cost, limited use, or having to decide which helmet for which ride. With the convertible, you can have it all!

Despite the chin bar, not all convertibles are backed by the ASTM F1952 certification required for downhill racing, so check your needs and preference.

Giro Switchblade MIPS Helmet

With full ear coverage in half shell mode and a double-D ring closure, the Switchblade is the beefiest convertible full face option, attracting many a full time enduro-er.

  • Weight: ~975g
  • MSRP: $250

Uvex Jakkyl Full Face Helmet 

The chin guard isn’t the easiest to manhandle, but at 630g (small), the Jakkyl HDE is one of the lightest convertibles available while maintaining an ASTM standard.

Leatt DBX Enduro 3.0 Full Face MTB Helmet

Leatt DBX 3.0 Enduro features their own twist on rotational injury protection and, you guessed it, a removable chin guard.

Bell Super 3R Full Face MTB Helmet

Finally, a convertible full face mountain bike helmet that needs no introduction — the Super 3R from Bell Helmets.

Recommended Full Face Mountain Bike Helmets

Fox Proframe MTB Helmet

  • Weight: ~750g
  • Vents: 24
  • MIPS: Yes
  • MSRP: $250

If removable chin bars aren’t your thing, but light weight and versatility is, the Fox Proframe is super light weight full-face helmet for enduro and ASTM certified for downhill racing.

MET Parachute MTB Helmet

According to MET, the Parachute is “the lightest ASTM certified full face helmet in the world,” weighing just 700g.

The standard (hot and heavy) full face has been around for some time, offering the ultimate protection for the most aggressive riders. By now, you’ve seen the inverse relationship between ventilation and protection, and this genre marks the extreme. As a result, full facers are also the heaviest MTB helmet with the highest profile. Chin bars are fixed and heavy duty straps often employ a double D ring for closure. Because most traditional full face helmets do not use a retention ring, it is of utmost importance that you get one that properly fits. I won’t bother listing weights (they’re all around 1,000g) as you’re not likely the weight weenie if you are wearing one.

Troy Lee Designs D3 Full Face Helmet

What full face buyer’s guide would be complete without a Troy Lee paint job… oh, and of course, the helmet it adorns? The D3 comes in a full carbon, composite shell, and entry-level Fiberlite – a lightweight fiberglass shell. Prices ranging from $295 to $495.

  • Weight: 1225g (Fiberlite) – 1075g (Carbon)
  • Vents: 26
  • MIPS: Varies by model
  • MSRP: $239 (Fiberlite) – $495 (Carbon)

SixSixOne Comp Full Face Helmet

The SixSixOne Comp full face helmet won favor among Singletracks readers for fit, comfort, breathability, and the ability to protect both your brain and budget.

  • Weight: $99
  • Vents: 18
  • MIPS: MIPS version $149 MSRP
  • MSRP: $99

Kali Shiva 2.0 Full Face Mountain Bike Helmet

Finally, for those who mix in a little MX with bike park, the most overbuilt helmet marketed to mountain bikers with no less than six certifications (including DOT), yet still weighing in at 1,190g — the Kali Shiva 2.0.

  • Weight:1190g
  • Vents: 18
  • MIPS: No
  • MSRP: $350 – $550 (Carbon)

Recommended Additional Bicycle Helmets

The following helmets share some useful mountain biking features and even meet specific safety standards for biking. I will showcase a few of these crossover helmets, followed by a short list of additional options if you find yourself in between disciplines.

BMX Helmets

Of course, there’s nothing wrong with rocking a full face BMX helmet on the trail. While you may suffer from heat stroke, there’s little left to penetrate, while offering durability only bested by moto lids.

Skate-Style Helmets

Skate-style helmets are round and smooth, with minimal venting ensuring a snag-free landing when you crash. Please note the term “skate-style,” as helmets dedicated to the act of skating may not be bike-certified.

Multi-Sport Helmets

Some folks dabble in mountain biking while their main jam may be skiing, skating, or whitewater kayaking. If you are said folk, you’re probably not reading this anyway, but if you happen upon this guide, your alternative sport helmet may cross-certify for biking, too.

Your Turn: Don’t see your favorite lid on the list, but can make a case for it? Tell us about it in the comment section below.

This article was last updated by Leah Barber on November 14, 2018.

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