Essential Knowledge To Choose A Great MTB Helmet

The feeling of blurred trees, dirt spraying beneath your rear tyre as you whip almost horizontal around berms. Plummeting through steep terrain, barely touching the rocks and roots strategically placed to challenge you. This is what we live for, the adrenaline and thrill of mountain biking.

There’s sometimes a fine line between thrill-seeking and recklessness but arming yourself with the right MTB helmet can help to tip the scale towards thrill-seeking. 

But what is the right helmet? 

There is so much information out there and even more options that it can be hard to know what is right for you and your riding style.

Never fear, I have done the hard yards for you so that you can concentrate on the trails. Let’s take a look at the questions you need to answer and the facts you need to know to choose the best mountain bike helmet for your ride. 

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Riding a rock slab in the TLD open face Mountain bike Helmet at St Helens MTB Trails

Helmet Safety Standards

It seems like a no-brainer to begin with the most important factor, safety – that’s the whole reason we wear helmets, right!?

However, it’s not only a smart choice to wear a helmet. Here in Australia, we are required by law to strap on a helmet when riding any type of bike. But not just any old helmet, to be legal a helmet must meet the AS/NZS 2063:2008 requirements and be approved by the governing body.

Approved helmets must show the appropriate sticker and this sticker is usually placed on the inside of the helmet.

Without rattling off the entire list of legal requirements a helmet must provide, here are some of the main ones:

  • Significantly reduce force of an impact
  • Be able to distribute force under impact
  • Durability under long exposure to sunlight, extreme temperature and weather
  • Durability under prolonged aging
  • Must provide a protective external shell
  • Must be fitted with an appropriate liner
  • Must be fitted with a retention strap (chin strap)
  • Mustn’t obscure vision

The most important takeaway from this is to only ever consider buying an Australian Standards Approved helmet. The reason these standards are in place is to keep you safe and this is the easiest step in choosing a helmet that is durable enough for mountain biking.

MTB Helmet Australian Standards sticker

How Do MTB Helmets Work?

Helmets are made from a polystyrene foam which compresses on impact, cushioning the blow and distributing the force. The foam is not very durable on it’s own, having a tendency to crack or catch on rough ground. This is why a helmet has a hard, smooth outer shell that keeps the foam together and allows the helmet to slide on impact, helping to avoid jerking movements that can cause neck injury. 

The outer shell is usually made from plastic, though some high end models use carbon fibre composite for better strength and lowered weight. For a comfortable fit, helmets are made with an inner harness that is designed to fit snugly with your head. This harness usually has a dial at the back to tighten or loosen for the closest fit.

Lastly, to ensure the helmet stays put on impact, a retention strap is used to clip around your chin.

Racing the Downhill run at Stromlo MTB park in my downhill mountain bike helmet

MIPS (Multi-Directional Impact Protection System)

If you’re looking into buying an MTB helmet, you’ve no doubt heard of MIPS. MIPS is another safety certification stretching beyond that of the Australian Standards.

MIPS stands for multi-directional impact protection system and implies the concept of reducing rotational force and the amount of energy generated in the event of impact. To achieve this, a thin liner is found on the internals of the helmet creating a small amount of flexibility and movement between the outer shell and the inner liner. This breakthrough in helmet design reduces the severity of injury and also decreases the chance of concussion.

Remember that this MIPS rating doesn’t replace that of the Australian standards, it is an extension upon those standards.

If you’re heading out on the trails, it’s just plain common sense to be as protected as possible. Therefore, I highly recommend purchasing mountain bike helmets with MIPS – or equivalent* – no matter the terrain you’re planning to ride.

*It’s important to note that some manufacturers have developed their own technology that is equivalent to MIPS but called by a different name. The important takeaway of this is to always purchase a helmet with some form of a tried and tested multi-directional impact protection system.

Open face mountain bike helmet with MIPS design

How To Choose The Correct MTB Helmet Style

As with nearly every aspect of mountain biking, whether it be buying a bike or purchasing any gear, determining what type of terrain you intend to ride should ultimately narrow down your decision. And the style of the mountain bike helmet is no different.

There are three main categories for mountain bike specific helmets. These are open face, full face and removable chin bar helmets. Each one is designed for a specific discipline in mountain biking, which I will explain below.

Take a look at the latest helmets and sales from Bicycles Online

Open Face Mountain Bike Helmets

Open face mountain biking helmets are built just as they sound, without any structure to cover your face. They provide maximum ventilation and the lowest cost. 

Due to the open face nature, these helmets tend to be best suited for cross country and trail type riding. Anything more extreme warrants more protection.

When searching for the right open face mountain bike helmet to buy, I recommend looking for one that extends down to cover the back of your head and the nape of your neck. These generally sit lower on your temples as well, offering the most protection.

Below are some of my favourite open face MTB helmets available.

Mat Walker looking calm in an open face MTB helmet on Air Ya Garns big jumps in Blue Derby Tasmania

Full Face Mountain Bike Helmets

Full face mountain biking helmets are the best of the best when considering protection and while all aren’t created equal, full face helmets will always provide more security than an open face lid.

Again, just like it sounds, a full face mountain bike helmet covers the riders entire head, stretching down to the neck and covering the riders face with a chin bar and large peak. The only open part of a full face MTB helmet is situated around the eyes for vision.

While full face helmets provide an increased amount of protection, they do also come with some drawbacks. Being an exclosed shell, generally full face helmets provide a fraction of the ventilation an open face helmet does and carries more weight with a higher price tag.

Full face helmets are purpose built for gravity mountain biking enthusiasts and if you plan on riding either downhill or enduro, I couldn’t recommend one enough.

Below are some of the best full face MTB helmets available.

  • TLD Stage MIPS
Mountain Biking on sunset at Dungog MTB Park in my Shimano Am901 SPD mtb Shoes

Removable Chin Bar Helmets

Moving onto a relatively new innovation, and perhaps the solution to only needing one helmet, is the creation of a convertible helmet.

A removable chin bar, or convertible, helmet fits the design of both the above two styles of helmet. Basically, a convertible helmet is designed to mimic that of a full face helmet with one major difference, the chin bar can be removed thus transforming into an open face helmet.

Convertible helmets are great if the idea of having one solution to fit all needs is your type of approach. If you dabble in many different styles of mountain biking and only want one helmet, this may be the option for you.

Perhaps the best feature of a convertible helmet is the ability to climb with the ventilation of an open face helmet, then descend with the protection almost matching that of a full face MTB helmet.

But as is the nature of the design, these helmets will never support the same structural integrity as a true full face mountain biking helmet. The removable parts aren’t as strong and have a higher chance of breaking or snapping on hard impact. For this reason, I wouldn’t recommend this option for high speed downhill riding or jumping.

Some great removable chin bar helmets are:

Mountain bike cornering around a excellent berm at Stromlo MTB Park wearing a convertible Mountain bike helmet

The Fit Of A MTB Helmet

Now that you’ve chosen which style of mountain biking helmet to buy, we can get into the specific details. These details are the same for each style and should be taken into consideration to find the correct match.

Having a perfectly fitted helmet may well be the most important detail to get right. A poorly fitting helmet can cause pressure and headaches, severely ruining the mood of your ride.

There are several factors that make up the difference between a good and poor fitting helmet.

  • General size
    Selecting the correct size is the first step to partnering with the correct fit. In most cases, you will encounter generic sizes such as; small, medium and large. But in the world of mountain biking, these sizes are not standard and can vary between brands. MTB helmet sizes are based around the measurement of the circumference of your head in centimeters and these sizes can be found on the inside of the helmet shell.
  • Shape and construction of the helmet’s harness
    A well built harness will not only provide the most comfort, but will aid in the safety aspects of the helmet impact protection as well.
  • Adjustability
    The more adjustability a helmet has, the more chance you are able to resize to the correct fit. As a bare minimum, you should be able to adjust all of the straps as well as the size of the harness circumference.
  • Location of securing straps
    If the securing straps aren’t fully adjustable, the locations of the fixings is an important factor to consider. Depending on the shape of your head, you may be left with a pressure point you cannot adjust and resolve.

Basically, for a mountain biking helmet to fit well, all of these key features need to be included with the design and then that design needs to match your head.

A mountain biking helmet should be able to sit firm in place on your head without the retention strap secured. There should be no movement and the fit should be comfortable with no pressure points. This is how you know you have the right helmet!

The most common sign that a helmet doesn’t fit correctly is pressure points created by the harness. But if the size fits, it may be that the shape of the helmet doesn’t match your head.

The reality is that there is no quick answer to this, no one size fits all. Everyone’s head is shaped differently and every brand of mountain biking helmet has a slightly different design. The best only way to determine the right fit is by trying on different brands.

Blue Derby Mountain Biking on rough rock garden on Trouty at Sunset

MTB Helmet Ventilation

Another major attribute to consider when talking about comfort is the ventilation of a mountain biking helmet, especially when talking about full face mountain bike helmets.

Poor ventilation on mountain biking helmets will lead to the heat that’s escaping from your head to be trapped, causing excessive sweat. This is not only uncomfortable, but will drain your energy excessively, impacting on your fitness.

The best MTB helmets use a combination of intake and exhaust vents to channel the airflow into the correct places and circulate the most air past your head to allow your body to regulate temperature most efficiently.

Regardless of the style of helmet, the main things to consider to achieve awesome mountain biking helmet ventilation are:

  • Number and size of vents
    With more big vents comes more airflow and with that, a lighter helmet – generally. This is the number one factor that results in good ventilation but can come at a cost of structural integrity. Just remember to check whether the helmet is suited to the type of terrain you plan to ride.
  • Location of the vents
    The location of the vents play a major role in airflow. And when correctly located, the intake and exhaust vents partner well together increasing flow.
  • Shape of the vents
    Shaping the vents correctly not only helps with increasing airflow, but also aerodynamics. Reducing the drag by swiftly channeling/funneling the air in and out of the appropriate vents.

A mountain bike helmet with a combination of the above designed into both the intake and exhaust vents will provide the greatest ventilation characteristics.

And if the above makes little sense, words to watch out for in regards to the highest ventilated mountain biking helmets are; high-flow, big-bore, large ventilation ports and no compromise airflow.

Obviously, an open face helmet is going to provide great ventilation in comparison but this doesn’t mean you don’t need to take the above into account. A poorly ventilated open face helmet can still cause excessive heat build up. 

Portrait wearing a fox proframe MTB helmet and Dharco MTB Gear

MTB Helmet Weight

With safety coming in as our number one priority, making a durable and tough helmet is necessary. But the catch is, we also want it to be lightweight.

Riding many kilometers with a heavy MTB helmet is extremely uncomfortable and can lead to severe neck pain and in extreme cases, ongoing neck injuries. Aside from the obvious issues with injury, wearing a heavy MTB helmet can slow your reaction time and impact on your focus and fitness.

Finding a balance between weight and protection is important and is viewed as a high priority among leading brands.

As a general rule of thumb, I would only ever consider the following maximum weight:

Downhill full face mountain bike helmets : <1200g

Enduro full face mountain bike helmets: <800g

Open face mountain bike helmets: <400g

The Fox Proframe is a great option for an affordable lightweight full face helmet.

Mountain biking down 23 stitches at Blue Derby Mountain Bike Park

Price’s of MTB Helmets

With all things in life, price is a pretty big consideration. And obviously, if you pick a helmet with the best of everything, you can generally expect it’s going to be the most expensive as well. 

To reduce the cost, you can look to sacrifice comfort traits that aren’t as important to you. For example, if you live in a cool climate then the best ventilation may not be a high priority. 

As a rough idea on price, here’s what you can expect to pay for each style of helmet.

Full Face Mountain Bike Helmets:

  • Top of the line – $500+
  • Mid level – $300-500
  • Entry level – <$300

Open Face Mountain Bike Helmets:

  • Top of the line – $300+
  • Mid level – $100-$300
  • Entry level – <$100

Convertible Mountain Bike Helmets:

  • Top of the line – $500+
  • Mid level – $300-500
  • Entry level – <$300

Never sacrifice safety when it comes down to money. Always purchase a helmet that meets Australian standards and preferably has a MIPS system (or equivalent) incorporated. And always choose the appropriate style of helmet suited to the terrain you ride.

When To Replace A MTB Helmet

Unfortunately, a helmet is kind of a one hit wonder and should be replaced after a big impact. The job of the helmet is to displace the energy throughout the structure instead of your head and in most cases of a big crash, this will crack the foam and leave the helmet useless.

If you continue to wear a damaged helmet, you are risking your safety as the helmet will not be able to sufficiently absorb another impact.

Obviously, MTB helmets are expensive and should only be replaced when necessary. If you think the crash wasn’t big enough to warrant replacement, thoroughly inspect the helmet for any large dents and/or cracks in the foam. This is a great sign that the integrity of the helmet has been compromised.

Along with crash replacement, a mountain bike helmet will eventually age over time. The foam generally won’t, but other components such as glues and straps will. There are no strict guidelines to follow here but you will nearly always find an age replacement guideline on the manufacturers website. But in the instance of obvious signs of decay, such as discolouring and fraying, you should most definitely consider purchasing a new helmet.

If in doubt, ask for a professional opinion – or just buy a new helmet. It may just save your life.

Some helmet manufacturers have a crash replacement program in which you can replace a broken helmet at a lower price. This is a great feature to watch out for and should be considered in the buying process.

Fox Proframe Helmet Review Close Up Image Of Scratches On The Helmet

Summing up

If you take anything away from this post, let it be the importance of safety. This is the whole reason we wear helmets in the first place and one aspect that should never be compromised. 

So choose your style of helmet from the style of riding you like, and give your local MTB store a visit. They’re your best source of information!

While there are other helmets out there not specific to mountain biking, I wouldn’t even give them a look in. This is because mountain bike helmets have been designed to protect against the rugged terrain that we ride. Yes, some road helmets may be lighter but they don’t have the same protection.

So with this knowledge I hope you find the perfect MTB helmet and start riding the trails with more confidence.