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Leatt MTB 4.0 AllMtn Review

A heavy-duty trail helmet with easy goggle and glasses storage but a bulkier fit
Leatt MTB 4.0 AllMtn
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Price:  $190 List | $151.99 at Backcountry
Pros:  Thick EPS shell, goggle and glasses storage, high-coverage
Cons:  Bulky, above-average weight, sweat management
Manufacturer:   Leatt
By Zach Wick ⋅ Review Editor  ⋅  Nov 7, 2021
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78
OVERALL
SCORE


RANKED
#15 of 23
  • Protection - 25% 9
  • Comfort - 20% 8
  • Ventilation - 20% 7
  • Features - 15% 8
  • Weight - 10% 4
  • Durability - 10% 9

Our Verdict

As the burliest half-shell helmet that Leatt offers, the MTB 4.0 AllMtn packs a thick EPS shell with great coverage for the rear and sides of the head, a sturdy, adjustable visor with storage space for goggles and sunglasses, and Leatt's 360 Turbine technology to reduce rotational forces from an impact. The added protection from the thick shell, however, comes with a bit of a weight penalty, a bulky fit, and a decent amount of sweat on long climbs. Out on the trail, we loved the easy goggle and sunglasses storage, but we found that we had to run the retention harness extra tight to find a secure and stable fit. This helmet doesn't top our test in any single metric, but it's a worthy option for anyone looking for a no-nonsense gravity helmet that won't bake their head on the way back up the hill.

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Leatt MTB 4.0 AllMtn
Awards  Top Pick Award Top Pick Award Best Buy Award Best Buy Award 
Price $190 List
$151.99 at Backcountry
$149.95 at Amazon
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Overall Score Sort Icon
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Pros Thick EPS shell, goggle and glasses storage, high-coverageComfortable, secure, airy, feature-richGreat ventilation, durable construction, not overly expensiveReasonably priced, comfortable, innovative sweat management system, MIPS, adjustable visorInexpensive, comfortable, versatile fit, durable
Cons Bulky, above-average weight, sweat managementOn the heavier side, non-adjustable strap splittersAverage protection, less versatile fit shapeModerately heavy, ventilation could be better, buckle failure in previous Consumer Reports testingLacks standout features, slightly heavy
Bottom Line A heavy-duty trail helmet with easy goggle and glasses storage but a bulkier fitThey pulled out all the stops for this new trail riding helmet, and it showsA solid all-around helmet that will keep your head cool on hot days and stand up to wear and tearAn affordable, quality helmet that checks most of our boxes at a reasonable priceThis helmet provides a high level of comfort and competitive performance at a wallet-friendly price
Rating Categories Leatt MTB 4.0 AllMtn Fox Racing Speedfra... 100% Altec Bell 4Forty MIPS Giro Chronicle MIPS
Protection (25%)
9.0
9.0
8.0
8.0
8.0
Comfort (20%)
8.0
9.0
7.0
8.0
9.0
Ventilation (20%)
7.0
9.0
10.0
7.0
7.0
Features (15%)
8.0
8.0
8.0
7.0
6.0
Weight (10%)
4.0
7.0
8.0
7.0
7.0
Durability (10%)
9.0
9.0
9.0
9.0
8.0
Specs Leatt MTB 4.0 AllMtn Fox Racing Speedfra... 100% Altec Bell 4Forty MIPS Giro Chronicle MIPS
Rotational Impact Protection System? 360 Turbine MIPS Smartshock MIPS MIPS
Weight (Ounces, Grams) 18.77oz, 532g 14.4 oz, 407g size L 13.5 oz, 381g, size L/XL 14.32 oz, 406g size Large 14.5 oz, 410g, size Large
Number of vents 13 19 15 15 14
Goggle or Sunglasses Integration? Yes Yes Yes Goggle integration No
Adjustable Visor? Yes Yes Yes Yes Yes
Sizes S, M, L S, M, L XS/SM, M/L L/XL S, M, L S, M, L
Certifications CPSC, CE EN1078, AS/NZ 2063 CPSC, CE EN1078, AS/NZS2063 CPSC, CE EN1078, AS/NZS2063, ASTM CPSC Bicycle for ages 5+ CPSC Bicycle for ages 5+, CE EN1078
Virginia Tech Helmet Safety Rating (if applicable) 5-star 5-star

Our Analysis and Test Results

With twenty years of designing protective equipment for both moto and mountain biking, Leatt certainly knows protection. For that reason, we were excited to get our hands on their latest helmet offering and put it through its paces. The MTB 4.0 AllMtn is the most substantial half-shell that Leatt offers with extended coverage, a bit of added heft, and more gravity-oriented styling than its counterpart the DBX 3.0. We found a lot to like in this affordably priced helmet, and we think it's a solid option for riders who love to push it on the descents and pedal back up to the top.

Performance Comparison


This thing is burly for a half-shell helmet.
This thing is burly for a half-shell helmet.
Photo: Zach Wick

Protection


When we pulled this helmet out of the box it quickly became apparent that it was designed with protection in mind. The EPS shell is among the thickest of any helmet we tested, and it drops down low on the back and sides of the head, providing fantastic coverage for a traditional half-shell helmet. the coverage is so good, in fact, that this lid strikes us as almost a middle ground between trail-oriented half-shells like our Editor's Choice, the Giro Manifest Spherical, and full-coverage open-face models like the Fox Racing Dropframe. The stiff visor is designed to break away in the event of a crash to protect your head and neck, and the shell packs dual-density EPS and EPO foam to help absorb both high and low-speed impacts. The helmet meets the CPSC, CE-EN1078, and AS/NZ2063 testing certifications.

The MTB 4.0 AllMtn's interior contains Leatt's proprietary 360 Turbine rotational impact protection as well as a highly-adjustable harness system. The 360 Turbine system comprises nine molded rings, or Turbines made from Leatt's energy-absorbing Armourgel material that are spaced around the foam shell's interior. The rings act as an interface between the rider's head and the shell, and they allow the helmet to rotate slightly in the event of an impact to reduce rotational forces applied to the head. The system works in a similar fashion to the MIPS system found in a wide variety of the helmets we tested. Fortunately, we didn't have a chance to try out 360 Turbine's effectiveness by hitting the deck in testing, so we can't comment on its effectiveness versus MIPS and other proprietary systems.

The rear and sides of the shell fit further away from the head than...
The rear and sides of the shell fit further away from the head than we're used to.
Photo: Zach Wick

Comfort


The MTB 4.0 AllMtn is a comfortable helmet and scored well in this metric. The foam shell's interior is lined with a thin layer of well-placed padding that seems to provide more cushion than it rightfully should. When you slide this helmet onto your head it settles into place nicely, and none of our testers noticed pressure points from the shell. The rear and sides of the foam fit further away from the head than many of the helmets we tested, which gives the helmet an airy feel despite its heft, but it also makes the helmet one of the bulkiest that we tested.

The harness system is easily adjustable both circumferentially and vertically and provides a wide range of fit. The dial at the back of the head that controls the circumferential adjustment has seemingly endless clicks. In testing, we found that we had to run the MTB 4.0's harness tighter than we typically would to secure it on our heads. The thick shell combined with the away-from-the-head fit means that the helmet doesn't feel planted on your head unless you crank the dial down tight. Using the vertical adjustment to drop the harness lower down the back of the head helped with the issue, but we still found ourselves reaching up and adding a click or two of tension while riding. The extra-tight harness didn't create too much of a comfort issue since it does a good job of pulling tension around the whole head rather than just pinching at the back.

The vents promote surprisingly good airflow for such a heavy-duty...
The vents promote surprisingly good airflow for such a heavy-duty helmet.
Photo: Zach Wick

Ventilation


For such a substantial helmet, the MTB 4.0 keeps your head surprisingly cool. The foam shell's roomy fit combines well with the 18 vents to keep air flowing across the top and sides of your head, and the interior foam padding is light and thin enough that it doesn't turn the helmet into a sauna on long climbs. On hotter days we did notice that this helmet gets a little bit warmer than the airiest models we tried out, but considering its coverage and heft we think it performs admirably.

Despite the good ventilation, we found that the MTB 4.0 doesn't do a great job of channeling sweat away from the face and eyewear. On longer, hotter climbs at low speeds we started to get sweat drips off the front of the helmet that ran down across our sunglasses and required a stop to wipe down the lenses before jumping into the next descent. Granted, our lead tester is known for excessive sweating while riding. We learned that stowing our sunglasses away in the dock port for longer climbs was the way to go.

Easy storage for sunglasses and goggles is one of this helmet's best...
Easy storage for sunglasses and goggles is one of this helmet's best features.
Photo: Zach Wick

Features


Leatt managed to pack loads of convenient features that make your life easier out on the trail into this lid. The adjustable visor and storage for goggles and sunglasses were among the easiest to use of any helmet we tested. Indexed visor positions and a sturdy adjustment mechanism allowed us to flip the visor up into its highest position with one hand and move our goggles up onto the helmet reliably and easily while riding. There's no grippy rubber pad at the back of the helmet to keep your goggle strap in place, but grooves in the outer shell do the job just fine. Storing sunglasses is similarly reliable and easy to do while on the move, requiring just one hand once you familiarize yourself with the location of the dock port. Rubber grippers do a good job of holding the sunglass arms securely while riding. The visor is also designed to break away in the event of a crash.

The MTB 4.0 AllMtn also packs a magnetic Fidlock chin buckle that's easy to operate with thick gloves, easily adjustable ear splitters that keep the helmet straps nice and tidy at the sides of your head, and the aforementioned 360 Turbine rotational impact protection.

With all of its bulk, this helmet will pack on quite a few grams to...
With all of its bulk, this helmet will pack on quite a few grams to your riding kit.
Photo: Zach Wick

Weight


Tipping the scales at a hefty 532 grams, our size-large test helmet was one of the heaviest models we tested. It's a full 180 grams heavier than the lightest model in the test, and it even outweighs the full-coverage Fox Racing Dropframe. We're not typically huge sticklers for weight, and we think that a heavier weight should be expected from such a heavy-duty helmet. That said, there are helmets in our test that offer similar levels of protection and coverage at a considerably lower weight.

The breakaway visor feature works well, and the visor reattaches...
The breakaway visor feature works well, and the visor reattaches easily.
Photo: Zach Wick

Durability


The MTB 4.0 AllMtn is by all appearances an exceedingly durable helmet. Over the course of our test session, we put this helmet through its paces and it came out the other side looking just about as fresh as the day we pulled it out of the box. The outer polymer shell resists scratching and scuffing well. After many close encounters with trailside branches during testing there our test helmet had no major dings.

As should be the case with any heavy-duty, gravity-oriented lid the MTB 4.0 is very well put together with no obvious weak point that we could find. The polymer shell wraps under the edges of the foam to protect from chipping and crumbling over time if you're prone to dropping your helmet on the ground occasionally like us. We tested the breakaway visor feature a few times, and it holds up well to repeated abuse. The visor easily snapped off with a firm impact or twist and then popped back on with no issues. The harness and strap mount locations are firmly molded into the shell, so there should be no wear and tear issues there.

Leatt provides plenty of strap length, but we had trouble keeping...
Leatt provides plenty of strap length, but we had trouble keeping the excess out of the way while riding.
Photo: Zach Wick

Value


With a list price that comes in below many of the top-rated helmets we tested and a mid-pack overall score in our test, we think that this helmet is a good value for the right rider. If you're hunting for a heavy-duty, high-coverage gravity lid that won't cost you an arm and a leg and will look good out on the trail, this might be the helmet for you. Riders hunting for maximum protection from a half-shell might be better suited looking at the full-coverage, open-face models we tested like the Giro Tyrant, and riders looking for a lighter-weight trail helmet in a similar price range would be better suited looking at the Fox Speedframe Pro.

Conclusion


The MTB 4.0 AllMtn may not be our favorite all-around helmet, but this beefy lid certainly has its merits. It shines in gravity-oriented applications like aggressive trail riding or light-duty enduro riding. We certainly enjoyed our time testing it getting rowdy on the trails, and we hope that this review helped you decide whether it's the right fit for your next helmet purchase.

If you're looking for a beefy, high-coverage trail helmet this might...
If you're looking for a beefy, high-coverage trail helmet this might be the one for you.
Photo: Zach Wick

Other Versions and Accessories


Along with the MTB 4.0 AllMtn, Leatt also offers the MTB 4.0 Enduro V21—a convertible half-shell/full-face helmet that uses the same upper shell as the AllMtn version that we tested. This helmet would be a good option for riders looking for a little bit more protection and versatility from the same design.

Zach Wick

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