One essential piece of kit for all mountain bikers is a good helmet. The best mountain bike helmets combine a high level of protection with features such as visors, ventilation and padding, and should rate highly for comfort and style too. We’ve extensively tested and reviewed MTB helmets on the market, and this is the very best of the best.

This guide is for regular open-face helmets, suitable for most trail and cross-country riding. If you’re looking for full-face or convertible lid for bike park riding or gravity use, then check our our guide to the best mountain bike full face helmets.

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1. Bell Sixer MIPS

A great helmet at a great price

Weight: 392g | Colours: White, grey, green, blue, Fasthouse | Sizes: S, M, L | Rating: 10/10

Reasons to buy: Great alternative if you’re not a fan of the Bell Super’s aesthetic

Reasons to avoid: Slightly fiddly vertical retention adjustment

Always at the forefront of helmet design, Bell’s Sixer brims full of tech and provides a superlatively comfortable fit. Varying densities of foam are used to build up the structure of the Sixer, each one optimised to absorb different impact velocities.

The visor tilts up in stages sufficiently to stash goggles beneath, and there’s a rubber strap grip at the back. We love the Float Fix Race retention device, which is highly adjustable with no pinch points, and your riding buddies will love the X-Static pads that help prevent funky smells building up on hot days. A great helmet, at a great price, test winner in the all-rounder trail riding category.

Read our full test review of Bell Sixer MIPS

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2. Fox Dropframe MIPS

Best mountain bike helmet for extra protection and coverage

Weight: 391g | Sizes: S, M, L, XL | Rating: 10/10

Reasons to buy: Great coverage, plenty of ventilation, lightweight, MIPS liner

Reasons to avoid: Visor isn’t adjustable

The Fox Dropframe is a half-way house between a full face and half shell. It doesn’t have a chin bar but there’s increased coverage at the side of the jaw, over the ear and back of the neck. It’s a distinctive design but it’s also incredibly lightweight for a helmet with this level of protection. 

Its stable – it literally doesn’t move even on the roughest descents – and also incredibly comfortable and, unlike the Giro Switchblade, is dead easy to put on because you can pull those side extensions slightly apart, so you don’t catch your ears. With 15 vents, the DropFrame ventilation is really good for a bigger helmet. Some helmets fit like a glove and are nice to wear – this is one of them. 

Read our full review of the Fox Dropframe MIPS helmet

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3. Bell Super Air Spherical

Best for versatility – can be converted into a full-face

Weight: 484g | Sizes: S, M, L | Rating: 10/10

Reasons to buy: Great ventilation, absorbent padding, fully adjustable visor, comfortable, plenty of protection, optional chin bar

Reasons to avoid: Old-school snap clasp

Bell’s new Super Air is the first trail helmet with Flex Spherical + MIPS technology. Crucially, it will move 10-15mm during an impact event, but it doesn’t encroach on the sizing or the fit – in fact the Bell Super Air is easily the most comfortable half shell we’ve tested. Bell’s retention device is also attached to the MIPS, so there’s no restriction of movement.

With 18 vents and four brow ports, air flow is excellent and if you do sweat there’s plenty of padding to soak it up, especially around the forehead. For trail use, the Super Air Spherical is comfortable, fits like a glove and offers a ton of protection via the dual-density closed cell foam construction. The best thing about this helmet is you can attach an optional chin bar to the front, which is available for an additional £89.99, which means this helmet also works as one of the best convertible helmets. 

Read our full review of the Bell Super Air Spherical helmet

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4. Troy Lee Designs Flowline

Best for style on a budget

Weight: 355g | Sizes: XS/S, M/L, XL/XXL | Rating: 8/10

Reasons to buy: Stable, multi-position visor. Light and well vented. MIPS liner for protection. Comfortable.

Reasons to avoid: Troy Lee Designs logo still demands a premium. Not as well ventilated as some.

One of the best compliments we can give the Troy Lee Designs Flowline is to say we instantly forgot we were wearing it. Even without the premium padding of the pricier A3 model, it’s instantly one of the comfiest helmets on sale. The 360º retention band is good, although it doesn’t come down as low on your head as the A3’s, and as such it feels a bit perched. The Flowline is very comfortable, safe as houses, about 60g lighter than the A3, and looks good. It’s easy to get a comfortable fit too, thanks to three sizes.

Read our full test review of the Troy Lee Designs Flowline helmet

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5. Giro Tyrant

Extra peace of mind without cooking your brain

Weight: 623g | Colours: Yellow, blue, black | Sizes: S, M, L | Rating: 10/10

Reasons to buy: Great for when full-face is too hot

Reasons to avoid: There’s a weight penalty

This quirky looking lid is a favourite of 50:01’s very own Ratboy, AKA Josh Bryceland. So does that mean it’s irrelevant for anything but jibbing? No, not in our opinion. Resembling a motorcycle trials helmet, the new Giro Tyrant adds a bit more protection to the enduro half-shell, placing it somewhere between an open face and a full face.

The outer hardshell is really durable, while inside there’s MIPS’ new Spherical liner, where the whole inner section of foam can rotate in the event of an angular impact. Dual density foam further helps with impact absorption, but even with all that extra coverage, there’s enough airflow to keep you comfortable on a summer’s day.

Read our full test review of the Giro Tyrant helmet

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6. Oakley DRT5

One of the most comfortable helmets we’ve experienced

Weight: 440g | Colours: White, blue/black, grey, green | Rating: 10/10

Reasons to buy: Excellent for hot heads. Superb comfort.

Reasons to avoid: Heavier than some helmets.

One of the most famous brands in sunglasses has branched out into the helmet market with the Greg Minnaar signature DRT5, and for a first attempt, it’s seriously impressive.

The BOA retention system, in combination with the MIPS liner, is luxuriously comfortable, while a silicone sweat gutter up front keeps drips out of your eyes. There’s also a clever set of clamps at the back of the helmet that’ll securely hold your sunglasses when you don’t need them.

At 440g the Drt5 is on the heavy side, but its secure hold on your head means it’s not really noticeable when riding. The finish is also brilliant, and it’s packing some extra features that are genuinely useful.

Read our full test review of the Oakley DRT5 helmet

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7. Fox Speedframe Pro

Well thought out, comfortable and protective

Weight: 437g | Sizes: S, M, L | Rating: 10/10

Reasons to buy: Form, function and a fair price

Reasons to avoid: Liner moves around a little. Internal shape doesn’t suit rounder heads.

A new kid on the block, but it has MIPS and a dual-density EPS, it also fits great and feels comfortable. It also looks way better than any previous Fox helmet we’ve tested, and while that shouldn’t matter, somehow it does.

Dual density foam is employed throughout, ensuring the Speedframe is as effective as possible in both high and low speed impacts, while the MIPS liner further helps dissipate rotational forces. Fox has ensured ample venting too, and the visor tilts right up if you want to stash goggles underneath. Finally, clever features such as the quick-lock magnetic strap closure help elevate the Speedframe Pro above its rivals.

Read our full test review of Fox Speedframe Pro helmet

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8. Giro Women’s Source MIPS

Best budget mountain bike helmet

Weight: 347g | Sizes: S, M | Rating: 9/10

Reasons to buy: MIPS, sweat-absorbing patting, indexed adjustment on the visor, good coverage

Reasons to avoid: Chin strap buckle is small and flimsy

The Source features Giro’s Roc Loc 5 retention device, MIPS liner, Coolfit Ionic+ padding. The visor has indexed adjustment that allows me to park my goggles under it. The shell extends down over the temples and at the back, giving it extra coverage.

It fits really well, it’s comfortable, and the retention device is easy to adjust while riding. The venting is good, and it holds goggles securely in place. While this version of the helmet is labelled women-specific, it’s no different to the Giro Source MIPS: the only change is a unique selection of colours and a smaller size range offering. 

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9. Specialized Camber

Best budget helmet

Weight: 392g | Sizes: S, M, L | Rating: 9/10

Reasons to buy: Great value for money, good ventilation, secure on-board glasses storage, lightweight, comfortable

Reasons to avoid: Minimal padding with no antibacterial treatment, less secure on rough terrain, fixed visor

Visually the Camber looks like the more expensive Ambush 2 but to keep the cost down it runs a single EPS layer rather than a dual-density construction. To add protection there is a MIPS SL liner. 

The padding is pretty minimalist, and there’s no antibacterial treatment, but the Camber features a really neat Integrated Fit system adjusted via a ratchet at the back. We can’t fault the comfort of the Camber, and Specialized has really nailed the details. As such, it’s lightweight and cracking value for money.

Read our full review of the Specialized Camber helmet

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10. Giro Montaro II MIPS 

Best helmet for hot conditions

Weight: 421g | Sizes: S, M, L, XL | Rating: 9/10

Reasons to buy: Roc Loc Air 5 MIPS protection, secure and comfortable fit, antimicrobial padding, adjustable goggle, detachable POV camera mount, excellent ventilation

Reasons to avoid: Old-style clasp, visor fixing screws can work loose, rear coverage less than competitors

The Montaro II uses the same in-moulded construction as the original version, where the EPS and Roll Cage reinforcement is placed in the mould with the microshell and then bonded. The new version gets a new Roc Loc 5 Air MIPS – Giro combines the movable liner and retention device into a single part, which eliminates bulk and weight. 

The retention device itself is easily the most accurate and is only indexed one way, so you can release tension quickly. Giro has really dialled the venting on the Montaro II – with 16 vents and sculpted internal channelling it’s notably cool. In addition, the fit is superb and it’s also excellent quality. 

Read our full review of the Giro Montaro II MIPS

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11. Troy Lee Designs A3

Comfort and style rolled into one

Weight: 411g | Sizes: XS/S, M/L, XL/XXL | Rating: 9/10

Reasons to buy: Stunning looks and superb comfort

Reasons to avoid: You’ll need deep pockets

To boost impact protection, the Troy Lee Designs A3 uses a dual-density EPS core with in-moulded mixes of EPP (expanded polypropylene) and EPS (expanded polystyrene), all wrapped up into a polycarbonate shell. To help deal with rotational impacts, the A3 gets a B-series MIPS liner integrated into the shell. 

Comfort and fit are excellent but that’s because the A3 is one of most heavily padded helmets on test. This cuts down on the ventilation but it’s nowhere near as sweaty as the old A1. The 360° retention device totally encircles your head and is height adjustable via some simple press studs. It also features a silicone brow pad (different sizes are included) and while this is effective, we found it can stick to your forehead. A great looking helmet that’s amazingly comfortable and packed with features, but demands a premium price.

Read our full test review of the Troy Lee Designs A3 helmet

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12. Endura MT500

Takes impact protection to the next level

Weight: 348g | Sizes: S-M, M-L, L-XL | Rating: 9/10

Reasons to buy: Ticks all the important boxes

Reasons to avoid: Not quite as finely finished as rivals

The MT500 is packed to the gills with features, including an adjustable peak, anti-bacterial padding, eyewear dock as well as a clip-off accessory mount for a headlight or helmet-cam.

The peak lifts far enough up to store goggles and the straps are held securely under the peak edges and a large (removable) clip at the back. We found the MT500 to be a little short front-to-back but it’s standard width and feels really comfortable even with the dial snugged up tight. Underneath the slightly dour looks there’s a cracking trail helmet, we just wish Endura would add a bit of bling to the skin.

Read our full test review of the Endura MT500 helmet

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13. Smith Engage MIPS helmet

A top quality helmet at a mid-range price

Weight: 344g | Colours: Orange, White, Black | Sizes: S, M, L, XL | Rating: 9/10

Reasons to buy: Excellent stability, comfort and styling

Reasons to avoid: Ventilation could be better

We’ve always liked Smith’s range of sensibly designed, uniquely styled helmets, and the Engage brings these qualities to a lower price point. You still get the MIPS liner, designed to reduce injuries from rotational impacts, and snug, secure, 360º retention system with dial adjustment.

It doesn’t boast quite the same level of venting as more expensive Smith helmets – the more basic construction means more material is needed – but it’s still cool enough for most riders and most temperatures.

Read our full test review of Smith Engage MIPS helmet

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How we test the best mountain bike helmets

All mountain bike helmets pass the current CE test so we’re taken it as read that they’ll work if you clonk your head on a passing tree. However, there’s currently no test for fit, venting or adjustability, which is why we’ve focused on these things when testing. To test the fit, we measured the shape of each one but that doesn’t reveal any hot spots, which is why we did lots of in-field testing, to test the true comfort. Riding hard we could also gauge the breathability and venting of the helmets.

Key features of the best mountain bike helmets:

The best mountain bike helmets sit a bit deeper on your head, extending down the nape of the neck, and they have extra coverage around the temples. Lots of helmets now incorporate some kind of rotational proection device, such as a MIPs liner, to reduce the risk of concussion. This can also be in the form of integrated reinforcement or crumple technology. There’s normally a visor, or peak, that you’ll be able to adjust up and down, and you may even see features such as integrated adapters to mount a POV cam or light, magnetic buckle closures, goggle strap clips and a storage bag.

Any bike helmet will work off-road but if you’re reading this, chances are you’re a trail warrior and you’ll want something a little bit more specific. A modern trail helmet will sit a bit deeper on your head and have extra meat over the temples and down the back, for greater protection. It’s likely to have some sort of built-in rotational device like a MIPs liner, to reduce the risk of concussion or some integrated reinforcement or crumple technology. You’ll get a visor that you’ll be able to adjust it up and down and you may even see integrated adapters to mount a head cam or light, magnetic closures, goggle strap clips and a storage bag.

Fully loaded, a good trail helmet isn’t going to be cheap but we believe it’s a small price to pay for something that could save your life.

Due to the trickle-down effect you will see some high-end features included on budget helmets but we’ve focused on the top-tier simply because that’s where there’s the greatest choice. These helmets are more refined, harder wearing and look pretty sick too.

How to find your helmet size

Get hold of a fabric or paper tape measure if possible. If you don’t have one, don’t try and wrap a metal tape measure around your noggin, it doesn’t work – believe us. In the absence of a fabric/paper tape measure, find some string and wrap that around your head and note its length.

Whereabouts to measure around your head? Essentially around the widest (biggest circumference) part of your head. Around your forehead and around the most prominent bit of the back of your head. Note down the measurement in centimetres. All helmets have size ranges and with your head measured it’s then easy enough to find which sizing has your head size covered.

How often should you replace a helmet?

You should replace a helmet after any slightly significant impact or crash. A lot of helmet companies offer crash replacement schemes so it’s worth checking out their websites for info about such things.

In terms of general lifespan, it’s typically advised that you should think about replacing your helmet every two to three years. Some companies in the past have stated a longer term than this but we’d feel a bit iffy using a helmet that’s had more than three years proper trail riding use. General wear and tear as well as things like UV degradation can have negative affects on the performance and reliability of your helmet.

Best mountain bike helmets protection standards

All bike helmets sold in the UK need certification. This means helmets must meet certain fixed test criteria like impact velocities, roll-off tests, and strap system strengths. This is a minimum and many modern helmets surpass these requirements by incorporating composite materials into sub frames or “roll cages” for extra protection.

Crash replacement schemes

If your helmet is involved in an accident, most manufacturers offer a reduced price crash replacement scheme. With proof of original purchase, these programmes can save you up to 50% on an expensive replacement lid.

EPS

EPS (expanded polystyrene) foam is at the core of every bike helmet and works exactly like a crumple zone in a car. Modern helmets use different densities and some are even reinforced with an internal mesh or webbing.

MIPS

Multi-directional Impact Protection System is a patented protective liner that slides when your head hits the ground, reducing the force of them impact and likelihood of a concussion or brain injury. MIPs is a branded product so several manufacturers do their own version usually with an equally ambiguous abbreviation.

Padding

Padding thickness and density has a significant effect on sweat absorption, cooling and comfort. Thicker internal padding may run a little hotter but you’re less likely to get sweat running down your neck and the helmet will generally feel more comfortable. Channels are often formed into padding to improve air flow and speed up drying.

Retention device

Like in a baseball cap, a retention device allows you to adjust the fit of the helmet. Most use a dial, which allows you to tune the tension/size with one hand while riding. You can also adjust the height using press-studs or a sliding clip.

Shell

To reduce dings and dents, the EPS it’s covered with a thin plastic micro-shell. This is usually in-moulded with the foam during the manufacturing process and can be one or several pieces.

Ventilation

Vents at the front of the helmet allow air to flow in and those at the back let it flow out again. Generally, the more the merrier but the shape and angle of the vents and how they integrate with the peak is key to keeping cool.

Visor/Peak

Being able to tilt the visor up means it doesn’t block your vision when riding with you head down but it also allows you to ‘park’ your goggles underneath. To hold the goggle strap securely, most helmets have a channel called a strap-gutter round the back but we also see clips or small tethers.

Goggle parking/strap gutter

On some helmets the visor can be tilted up so you can ‘park’ goggles underneath when you’re not using them. Usually this feature comes hand in hand with a strap gutter – a shallow channel on the back of the helmet that holds the strap in place.

Bottom wrapping

To add extra protection to the lower edge of the EPS the micro-shell often wraps under the bottom of the helmet.

Sizing

Helmets come in various sizes. Small, medium and large is pretty standard but you also see overlapping sizes like S/M and M/L. One company’s medium can also be another’s large and some helmets are long and thin, while others are short and squat. All of which means there’s no consistency in sizing or fit and you should always try before buying.