MTB
What makes a mountain bike helmet safe, who certifies it and, of course, if you drop it is it a write-off? We speak to Swedish protectives experts POC to get the lowdown.
Mountain bikers pretty much all understand the need for a good helmet – whether from a low-hanging branch across the trail or a big slam, common sense says a decent lid is compulsory.
But who declares a helmet as suitably safe before it's put on the market, what certifications exist, what factors are considered in certifying it, and – that age-old question – does stickering a helmet make it unsafe?
We spoke to Damian Philips from POC to find out a bit more about helmets and their certifications.
How important is fit? What defines good fit?
A helmet should stay in place whenever used and under load. If part of your head is exposed when you hit the ground, the helmet won’t protect you as well. Finding the right size helmet is paramount, as too small a helmet won’t come down on the head and cover it properly, while too big a helmet might move around too much on the head. A well fitting helmet stays in place on the head, without creating any pressure points.
What European safety certifications (CE) exist for MTB helmets?
EN1078 is the only mandatory European Standard and covers all bicycle helmets. ASTM F1952 – 15 is an American standard, but it is relevant as the downhill helmet bicycle standard. NTA8776 is a new Dutch standard for Speed E-bikes and Pedelecs.
There are a host of different testing institutes and notified bodies that offer and support helmet testing and certification according to European and American standards etc.
What does the safety testing involve?
It's quite a detailed picture. EN1078 testing involves impact testing with eight different headforms, sized according to the size range of the helmet, and with different anvils (flat and curb-shaped for EN1078). This includes hot (+50ºc, 4-6h), cold (-20ºc, 4-6h) and wet conditioning and artificial ageing (spraying ambient tempered water 4-6h at the rate of 1l per minute and ultraviolet irradiation by a 125W xenon-filled quartz lamp for 48h at a range of 250mm).
In addition, roll off testing and retention testing is carried out to make sure that a helmet doesn't slide off the head easily and that the straps and buckles and so on won't fail under load. Further, materials (pads, straps etc) are tested for harmful substances (analysis of Azo Dye) and the colour fastness to perspiration is tested.
What is SPIN? Should we all have it?
Helmets are certified to protect users from linear impacts, but falls often result in angled, or oblique, impacts. These can lead to a rotation of the helmet and head. Rotational impact protection is necessary as the force required to cause head injury from an oblique impact is often lower. Driven by our mission, and from working closely with our medical experts in our POC Lab, we know that oblique impacts are common and can cause serious head injury due to a rotation of the helmet and head.
To counter oblique impacts, we created SPIN pads, which are optimised to provide rotational impact protection based on the precise location inside the helmet. SPIN pads provide a new layer of protection by using various pad technologies which can shear in any direction during an oblique fall. SPIN pads allow the helmet to move relative to the head, which can reduce the amount of force transmitted to a user’s head and brain in the event of an oblique impact.
[RB note: MIPS is a similar system to POC’s SPIN; it can be found in other manufacturers’ helmets – look for the MIPS branding.]
Are MTB helmet peaks dangerous? Should they break away more easily, as is now mandatory in some motorcycle racing?
We see that smooth shells test better in oblique impacts, which is why we have designed all our full-face helmets with a breakaway visor/peak. See our Coron helmets for an example.
Does a helmet-mounted camera compromise safety?
If the camera mount doesn’t fall off easily, it will most likely add rotational forces to the head in an impact. This is certainly not good, and we would advise against adding things to a helmet which will interfere with the slide and potentially catch on objects on the ground.
Is it true that applying stickers is bad for the helmet, or simply an age-old myth?
There is not a great deal of evidence around to support or counter this. But as you would imagine it really depends on the type of sticker. Polycarbonate (PC) is a sensitive material, so stickers that contain certain chemicals might have a negative effect. This is why PC shells shouldn’t be painted by consumers and, as a rule of thumb, we'd suggest avoiding any form of extras on a shell.
Should we replace helmets after any knock to the head, small or large? What if I drop my helmet?
There are no rules on what constitutes a small fall or a big fall and everyone will feel the effects of a fall differently. So, it's impossible to provide a simple response. However, it does depend greatly on the type of helmet you use. EPP-lined helmets, which are designed to be multi-impact, naturally can handle repetitive impacts, as opposed to single impact EPS, but even EPP has a limit and it’s important to inspect the helmet regularly for signs of wear and tear.
Dropping it, which happens to us all, should not be a cause to change a helmet, but if you do it regularly and don't look after the helmet, then it might be that you need to replace it sooner than you would otherwise want to. One simple rule is to take good care of it.
Are full-face chin guards safety-rated?
There is a test of the chin guard in the ASTM F1952 – 15 standard. It’s a pass or fail test.
Do all full-face lids have to pass the ASTM F1952 – 15 test?
No, this isn't a mandatory certification. There are full-face helmets on the market that aren't certified according to ASTM F1952.
Is there a maximum lifespan for a helmet that hasn’t been crashed in?
Helmets are an essential bit of kit and if looked after properly will offer years of great service, but it’s also fair to say helmets are often thrown in a bag or back of a car at the end of a good day's riding and have to manage a fair amount of day-to-day wear and tear. In general, we'd recommend that you replace your helmet every three years.
How important is overall head coverage? Is this safety tested, or does CE certification only test for impacts to the foam, no matter what shape/size the helmet?
As the highest-allowed G value under impact is sub-250g, a helmet with minimum coverage that records 249g in every impact would still pass the required tests, just like a helmet with extended coverage and sub-50g values.
We see that a lot of real-world impacts end up at the lower parts of the helmet, which is why we've designed and extended the coverage around the head, especially in the back. This is our own choice, as we want to create what we believe will be safer helmets. From a testing point of view, we'd certainly welcome the testing to be carried out lower down on the headform than at present, to take these impacts and scenarios into account.
What materials are used in a helmet? Is there a way of defining one as ‘better’ than another, safety-wise?
Most bicycle helmets are built around an EPS core (liner) and a PC (polycarbonate) shell. Some will have an ABS, carbon-fibre or fibreglass (hard) shell instead of the thinner PC shell.
EPS and PC offer very good protection and are often very lightweight. EPS is built, however, with single-impact protection in mind and as such doesn't offer multi-impact protection properties. Adding a hard shell to the helmet will make it more durable, but an EPS core is designed to permanently deform after a fall and as such will not offer full protection the second time you fall on your head.
This is why we use an EPP core and a hard shell on most of our DH and enduro helmets. EPP doesn't permanently compress in an impact as it's elastic, so it returns to its original shape, meaning that you can keep using the helmet after one or several lighter falls.
The liner and shell are major parts of the helmet, but other materials, such as aramid, carbon and so on all add different elements and safety features to a helmet.
Where do people find the safety ratings of their helmet? Where is it written?
The certifications should be listed on the inside of the helmet, but you can often find it on the size sticker on the shell or on the box label in the store.
