Protecting your head is vital in the rough and tumble world of mountain biking, where crashes can be an all-too-frequent occurrence. That’s why getting the best mountain bike helmet possible is hugely important to staying safe and comfortable.
We’ve rounded up our pick of the best trail helmets currently on sale, plus our advice on what to look for when you’re buying a new lid.
Best mountain bike helmets 2020, as rated by our expert testers
- Bell 4Forty MIPS: £90
- Giro Manifest Spherical: £250 / $260 / €260
- Giro Tyrant: £135
- Scott Stego: £135
- Smith Sessions MIPS: £140 / $160 / €160
- Troy Lee Designs A3: £200 / $220
- B’Twin All Mountain: £29.99
- Fox Dropframe: £130
- Giro Fixture MIPS: £69.99
- Sweet Protection Trailblazer MIPS: £160 / $180 / €180
Bell 4Forty MIPS
- £90 as tested
- Comfortable to wear and the fit system is easy to adjust
- Great airflow and top-value
- It could do with indexed visor adjustment
Stacked with features, the 4Forty is pretty affordable. The large vents mean it has impressive airflow over the top of the head to help reduce heat buildup on long climbs.
We found its shape is well-suited to those with rounder heads and the fit system is easy to adjust with an indexed dial on the back of the lid.
The peak adjusts high enough for goggle parking, too.
Giro Manifest Spherical
- £250 / $260 / €260 as tested
- Well vented, comfy and has lots of features
The Giro Manifest Spherical is noticeably more breezy than other trail helmets, even at lower speeds, thanks to its highly ventilated design.
There’s a decent amount of coverage, and despite this, it’s still impressively light.
The tension around the head feels nice and we suffered zero hotspots during testing. the padding is thick enough to keep things comfortable and absorbs enough sweat to avoid any dripping.
There’s no getting away from the price and while the safety features are great they are the same as the less expensive Giro Tyrant. However, because of how well it performs, it has become a go-to for our tester over helmets.
- £135 as tested
- Comfy and well-ventilated
- Loads of coverage, similar to a lot of convertible helmets such as Giro’s Switchblade
- Looks might not be to everyone’s tastes
The Tyrant helmet from Giro represents a new-school attitude to trail riding where more protection is a must-have at the expense of a little weight and heat dissipation.
It uses a MIPS Spherical system to help protect your brain in a crash and offers lots of low-down protection at the rear thanks to its design.
On prolonged, slow climbs it can get a bit hot but we think it’s a price worth paying for the extra coverage on offer.
Scott Stego MIPS
- MIPS technology increases protection
- Very comfortable, offering plenty of protection
- Plenty of ventilation helps reduce heat build-up on climbs
We’ve been big fans of the Stego ever since it was launched, but this MIPS version uses clever technology to keep you safer than ever. Using a plastic liner inside the helmet, the MIPS system reduces the rotational forces that can cause brain injuries.
It only comes with a 15 to 20g weight penalty, so there are barely any drawbacks to the system.
Elsewhere, the Stego has a squared-off profile that might not be popular with some, but it does give plenty of coverage to your temples and the back of your head, making it ideal for anyone looking for a lighter trail lid with a little extra protection.
It’s also a very comfy lid with plenty of airflow thanks to large channels that direct air over your head. The fully in-moulded shell also means that it puts up with the rough and tumble life of mountain biking very well too.
Smith Sessions MIPS helmet
- £140 / $160 / €160 as tested
- Great cooling and good comfort
- MIPS liner
- Fairly pricey
The Smith Sessions MIPS helmet uses a combination of two third-party protection technologies for safety: MIPS to reduce rotation impact and Koroyd which crumples to absorb the forces caused by impact.
These features don’t get in the way of ventilation and the helmet provides great cooling. The downside is that the large vents did make it easy for bugs to fly in while testing.
The retention system is easy to adjust, vertically and with the index wheel, and the helmet didn’t move around too much even with goggles stowed on top.
Overall, the Smith Sessions MIPS helmet has a host of features and although it’s fairly pricey it does offer good value for money.
Troy Lee Designs A3
- £200 / $220 as tested
- Great fit and superb comfort
- MIPS liner
- High price
The Troy Lee Designs A3 is TLD’s premium trail helmet and builds on the success of the A1 and A2, which both set a benchmark when it came to mountain bike helmet design.
The A3 is an iconic TLD shape, but this has;t stopped TLd scrimping on safety. The helmet uses two layers of foam to protect you against different impact speeds and uses a MIPS liner too. It was given a five star rating by the Virginia Tech Helmet Ratings project.
Wearing the A3 out on the trail there is a decent breeze over your head and the magnetic visor doesn’t rattle around like on other helmets. It’s a bit heavier than some but it is extremely comfortable, and we’d argue it’s worth the price tag.
B’Twin All Mountain
- £29.99 / €40
- Good on-head stability and comfortable
- Bargain price and good head coverage
- Can get quite hot on long climbs
For the price, the B’Twin All Mountain is an impressive lid, offering plenty of coverage, staying comfortable on long rides and refusing to budge over rough terrain.
It’s compatible with plenty of riding glasses but lacks an adjustable retention cradle seen on most other lids. As long as you buy the right size helmet for your head, this shouldn’t be a problem.
Although we didn’t mind its looks, they might not be to everyone’s tastes.
- Great, full-head coverage
- Good venting and reasonable weight considering the coverage on offer
- Fixed peak and no adjustment cradle
Like the Giro Tyrant, the Fox Dropframe is another example of the new-school open face, extra-coverage trail lids that look similar to full-face helmets with the chin bar removed.
Lids that look like this tend to divide opinion, but there’s no denying the extra protection is attractive.
The Dropframe doesn’t have MIPS but does feature a dual-density EPS shell. And because it doesn’t have an adjustable retention cradle, its fit can only be adjusted by changing the pads, so trying before you buy is essential.
Giro Fixture MIPS
- MIPS protection, good looks and well-vented
- It stays put over rough terrain
- Fixed visor can be a pain
The Fixture is a bit of a bargain, considering the amount of tech on offer. It’s got MIPS and an adjustable fit system with a one-size-fits-all design that spans between 54 to 61cm.
Although the visor is fixed and the interior padding isn’t as plush as some lids, for the price the Fixture is a great performer.
Sweet Protection Trailblazer MIPS
- £160 / $180 / €180 as tested
- Comfortable and easy to adjust
- MIPS protection
- Average ventilation
The Sweet protection Trailblazer has a multipiece shell with different thicknesses and shapes to best protect your head. It also uses MIPS technology to minimise rotational force causing damage on impact.
when it comes to fit, the Trailblazer has an index dial that is easy to adjust. It comes with two thicknesses of pads, which unlike other helmets you can distinctly feel. The helmet feels secure when going over bumps.
This helmet has 16 vents, but we found ventilation to be fairly average, making this a cool weather helmet. We also found it difficult to use this helmet with large goggles. This means it’s not the most versatile, which might put you off paying the full £160 price.
Mountain bike helmet buying advice
The best mountain bike trail helmets manage to balance the often-competing needs of protection, ventilation, comfort and weight.
Helped by the rise in popularity of enduro racing, many open-face lids now offer greater coverage around the back of the head and the temples than cross-country or road-style helmets, helping to boost protection.
Unless you care about every single gram or really want ultimate cooling, that makes them a sensible bet for the majority of riders.
Most bike helmets use some form of expanded polystyrene, or EPS foam, formed around a core of another, tougher material to provide cushioning in the event of an impact.
The foam crushes when it’s struck, spreading and delaying the force of the impact being transmitted to the wearer, hopefully to a level that will prevent injury.
While the impact resistance of helmets is covered by a number of test standards to ensure they perform when they’re needed, manufacturers have been introducing extra technology to try and improve on this.
One such technology is MIPS (multi-directional impact protection system), which uses a floating plastic liner between the head and the EPS structure, which reduces the amount of rotational force transmitted to the brain during a crash.
Rotational force is responsible for a large number of injuries, including brain damage, so while it makes manufacturing, and thus retail, prices more expensive, many manufacturers now incorporate MIPS into their helmets.
Most bicycle helmets now have a hard plastic outer moulded to the EPS structure. This is known as in-moulding and provides protection against minor bumps and scratches that would otherwise damage the EPS.
On cheaper helmets, this tends to be limited to the top and sides of the helmet. More expensive, fully in-moulded helmets extend the plastic protection down and around the rim, making it much more effective at fending off damage.
While the extra coverage of trail-style helmets is more than welcome, it does get in the way of airflow, which can mean a much warmer and sweatier head in hot weather or when you’re pushing really hard.
Happily, thanks to the increasingly clever use of materials and design, it’s now possible to make a lid that’s almost as cool as a conventional design.
Having lots of vents is important, but it’s the internal channels that help airflow in through the front, over the head and out the back that makes all the difference.
Look for big vents on the front and rear, with deep channels on the inside of the lid.
How well a helmet fits will depend on the size and shape of your head. Many people tend to get on with certain brands that use a particular shape, but finding the right one is very much a case of trial and error.
If possible, bearing in mind the latest Covid-19 guidance, go to your local bike shop to see how you get on with different lids or ask your friends if you can try theirs.
The main thing is to ensure you can get the helmet sitting securely on your head so there are no pressure points or undue movement.
Most helmets will have a retention system of some kind to allow you to adjust how tightly it fits onto your head. Many of these will tighten and loosen around the circumference of the head, although some also adjust in other ways.
However it works, make sure you can operate the system easily in gloves and that it doesn’t trap hair or pinch flesh.
Also ensure that you can adjust the straps to get a solid fit that’s not restrictive and that when fully adjusted you have a clear, unobstructed view, especially when you’re in an aggressive, head-down riding position.
Check that the peak can be adjusted so that it keeps the sun out of your eyes without getting in the way or flapping about when you ride. If you like to ride wearing glasses, make sure they fit comfortably with the lid.
While weight might seem like a minor consideration compared with a helmet’s other characteristics, a lightweight helmet will be a much more pleasant place to be after a long day on the bike.
A light lid is much less likely to try to move about as you ride, too.
A number of helmets on the market now come with a chin guard that can be removed. This is largely in response to the growth in enduro racing, where long climbs benefit an open-face lid to help you breathe and stay cool, while gnarly descents mean the additional protection from a full-face-style lid is desirable.
With a removable chin guard, riders get the best of both worlds.
The compromise is often weight because, if the helmet has full ASTM downhill certification (so it can be used as a DH race helmet), there needs to be extra protection built in. Not all of the convertible helmets meet this standard, though.
Whether you choose a convertible helmet is up to you, but we’re definitely seeing more on the trails these days.
Anything else I might need to know?
If you love to record and share your rides online, then you’ll be pleased to know that more and more manufacturers are integrating removable camera mounts into their helmets.
These allow a secure fitting for your camera but also mean you can go back to having an unfettered helmet when you want to.
Many enduro-style lids also allow you to use goggles to provide almost impregnable eye protection. Look for helmets with a peak that lifts up high enough for you to be able to fit the goggles underneath and a strap of some kind at the back to keep them secure.
This article has been updated since it was first published so some comments below may be out of date — last updated 21 May 2021