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B’Twin All Mountain helmet review

Can Decathlon’s budget All Mountain lid offer more performance than its price tag?

Our rating 
4.0 out of 5 star rating 4.0
GBP £29.99 RRP | EUR €40.00
B'Twin All Mountain mountain bike helmet

Our review

It’s impressively comfortable and stable and has great head coverage at a bargain price
Pros: Comfortable and stable; compatible with almost any glasses; offers top levels of head coverage; bargain price
Cons: Can get quite hot on the climbs; polarising looks
Skip to view product specifications

Normally, if something sounds too good to be true then it often is, and when I first saw the price of the B’Twin All Mountain helmet I thought there must have been an error because it just seemed too cheap.


As it turns out, the lid does retail for a mere £29.99 / €40, but what kind of performance can you expect for that price?

B’Twin All Mountain helmet specifications and details

Only available in two sizes – medium and large – to fit heads from 53 to 59cm or 59 to 61cm circumferences, the helmet uses an elastic cradle to create the tension required to keep it on your head.

And while most lids have a BOA-style tension-adjuster and a full-circumference cradle made from plastic, the B’Twin’s elastically-adjustable cradle simply wraps around the rear of your head – its fit adjusted by the pressure generated by your head in the helmet, stretching the elastic strap.

B'Twin All Mountain mountain bike helmet
The helmet’s cradle is elastically adjusted.
Andy Lloyd

The helmet’s main body is made from a Polyurethane EPS-style foam that’s wrapped in a harder polycarbonate shell to protect it from bashes, knocks and puncturing. The shell expands around the EPS on the bottom of the lid’s rim, so there’s no exposed foam that’s prone to damage.

It’s got an angle-adjustable and removable visor and the main buckle has Y-adjusters for your ears and a standard fastening clip.

There are seven vents: three at the front of the helmet, two on the top and two small ones at the rear. The interior padding is attached with Velcro and can be removed. There are large cut-outs for ears and the rear of the lid extends a long way down over the back of the head.

B’Twin All Mountain helmet performance

Its looks are fairly polarising thanks, in particular, to the large, angular ear cut-outs and low rear section. This sort of helmet design isn’t especially new, Fox’s Dropframe and Giro’s Tyrant paved the way there, but none of them are going to win a beauty contest.

Once it’s on your head, its looks are forgotten because of the fantastically comfortable fit. It feels plush and there were no pressure points or excessive tightness around the head. Its overall shape is good, too, and it certainly fits snugly.

However, the helmet’s auto-adjustability is limited and if you fall outside of the lid’s sizing scope you’re out of luck, and it’s inadvisable to wear an ill-fitting lid. This problem is shared across all size-specific lids, though.

It feels light on the head and the low-reaching rear is a welcome design element that offers plenty of coverage, hopefully improving the protection offered in a crash.

Out on the trail, the lid didn’t wobble or shake around on the descents or the climbs and I didn’t find myself constantly readjusting it. This is impressive considering its elastic fitment system, that, on first glance, appears like it might not be up to the job of keeping it in place. I found that it manages to keep the lid where it needs to be, putting those concerns to bed.

The adjustable peak lifted high enough to not encroach my peripheral vision but didn’t open up enough to provide a parking space on the front of the helmet for a set of goggles. However, the large flat area on the back of the lid is big enough to store goggles as long as you’ve turned them through 180 degrees.

B'Twin All Mountain mountain bike helmet
The peak has enough adjustability to raise it high enough out of your peripheral vision.
Andy Lloyd

On tougher, longer climbs it did get quite hot, causing sweat to drip into my eyes. The seven vents weren’t adequate at letting enough air to circulate around the lid to stop my brows from getting saturated in sweat.

This problem could be solved with more or larger exhaust vents on the rear of the lid to let hot air escape or create a better flow of air from front to back.

One of the lid’s most impressive features is its compatibility with riding glasses. With no wrap-around plastic cradle, sunglasses arms can pass underneath the lid’s shell without contacting the cradle. If the arms are particularly bulky, they can be uncomfortable to wear with certain helmets, but the All Mountain’s design means this isn’t an issue and I had no problems with a host of different specs.

Thankfully, I didn’t test how much protection the helmet offers in a crash, but it does comply with the EN 1078 cycling standard.

B’Twin All Mountain helmet bottom line

At just £29.99 / €40 the All Mountain helmet is mighty impressive, especially considering the potential shortcomings of its fit adjustment.

It remained comfortable during the test period, didn’t shake or move when I didn’t want it to, and its shape offers plenty of head coverage. It’s also comfortable to wear with a host of different glasses unlike some other lids.


It can get quite hot on the climbs and its design might not appeal to everyone, but for the price you can’t go too far wrong.

Product Specifications


Price EUR €40.00GBP £29.99
Weight 367g (Large) – Size large
What we tested B’Twin All Mountain helmet in blue
Year 2020
Brand Decathlon


Features 100% Polyurethane EPS foam inner 100% Polycarbonate shell Complies to EN 1078 cycling standard 2 sizes Elastic strap auto-adjust fitment 7 vents
Helmet type Mountain bike open face
Smart helmet no