Cycle helmets are often a highly divisive topic, surrounded by a wealth of myths and misunderstandings. This post is NOT going to tell you whether or not you should wear a helmet. Instead, I will try to give you some clarity about cycle helmets.
Back in 2014, I had a crash, and I still distinctly recall the sound my helmet made as it scraped along the tar. I also remember thinking at the time how glad I was that it wasn’t my head scraping against the road surface. As a result, I believe unquestionably that cycle helmets offer protection.
The only question is what level of protection.
Helmet Design Specifications
For that, we first need to look at the different standards for cycle helmet design. The UK has it’s own standards organisation, called the British Standards Institution, or BSI, and for a long time now the BSI has aligned its standards with that of the Europe’s General Product Safety Regulations , or GPSR.
For cycle helmets, as long as a helmet passes either the BSI EN 1078 standard, or the EU’s EN 1080 standard, it means it’s been assessed to meet either. If the helmet is CE certified, it also means it meets EN 1080.
What are cycle helmets designed to protect against?
That’s all well and good, but what does this mean in practice?
The answer is simple: far less than you probably thought. This line, for example, from page 11, states that helmets are in theory designed to offer protection against falls of maximum 1.5 metres, if landing on a flat surface, or 1.06 metres, if landing on any edge.
Chances are your head is significantly higher off the ground while you’re cycling.
More importantly, those heights apply to the test, which involves dropping the helmet perpendicularly, and there is zero adjustment made for any forward velocity the rider may have. In fact, the standard limits the maximum velocity the helmet should have when being tested.
A helmet on the back of the head…
Further, that degree of protection only exists if the retention system (the helmet straps) offer no more that 2.5 cm play, while secured on your head, and if the helmet is worn on top of your head. The standard specifies it should fit above your ear holes. All those people who wear their helmets strapped effectively on the back of their heads gain precious little to no protection, despite often being most vocal about the supposed need to wear helmets.
The following extract if from Page 22 of the standard (I added the bold emphasis):
“With every helmet, clear information in the language of the country of sale shall be given as follows:
a) that the helmet can only protect if it fits well and that the buyer should try different sizes and choose the size which feels secure and comfortable on the head;
b) that the helmet should be adjusted to fit the user, e.g. the straps positioned so that they do not cover the ears, the buckle positioned away from the jawbone and the straps and buckle adjusted to be both comfortable and firm;
c) how the helmet should be positioned on the head to ensure the intended protection is provided (e.g. hat it should be placed so as to protect the forehead and not be pushed too far over the back of the head);
d) that a helmet cannot always protect against injury; ”
Do cycle helmets protect you against cars?
So what about impact with cars – what does the standard of your helmet say about that? Now that’s an easy question to answer: it doesn’t, because no cycle helmet is designed to protect against anything more than a relatively slow speed fall, involving no other vehicle. Cycle helmets simply are not designed to protect against cars, and if you don’t believe me, please go read the entire standard. After all, we’re all grown-up enough to have moved away from basing objective views on what “my mate in the pub” has said, aren’t we?
Also, go place a cycle helmet on the ground, then slowly drive over it with a car, and watch it disintegrate. The amount of force you’d be exposing it to vastly exceeds what it could possibly withstand.
The human skull
This brings us into interesting territory: how strong is the human skull, and how strong is a cycle helmet? It is commonly accepted that the human skull requires forces of greater than 5 GigaPascal (GPa) concentrated over a small area (less than 5cm) before it would fracture. In adults, the human skull often may require forces greater than 6,5 GPa to crack.
In their 2006 research paper, N J Mills and A Gilchrist, from the Uni of Birmingham, quite clearly state that cycle helmets’ only job is to slightly reduce impact to (hopefully) below lethal level. They go on to say that “requires a certain minimum force before it starts to crush. Until this minimum is reached, the head must absorb the impact. This means that, although helmets are designed to limit the impact (deceleration) to a just sublethal level, they would not reduce it much below that. In these cases, sublethal translates into anything from a very bad concussion to a coma.”
To review all of this, cycle helmets do not offer any designed protection against crashes involving any other vehicle, and while it may offer your head some protection against being cut by glass, that degree of protection would be almost irrelevant compared to the massive impact force caused by being hit by a car.
Cycle helmets do offer a slight absorption of impact, but not enough to prevent concussion, nor indeed coma. Also, polystyrene – what cycle helmets are made from – is rated at 3.4 Gpa strength, while the human skull exceeds 5 GPa – that’s a huge difference, and simply means your skull is far harder than your cycle helmet.
I started this post by saying this isn’t an argument for, or against cycle helmets. It’s your head – do what you want with it.
On the roads, I tend to usually ride with a helmet (but not always) while on traffic-free paths I tend to ride without it. I strongly support your right to choose what you feel is right for you.
However, whatever you decide to do, now that you know that cycle helmets really only protect against grazes and scrapes, and precious little else, please will you stop with the “My mate crashed his bike and smashed up his helmet. If it wasn’t for his helmet, his skull would’ve been smashed” stories, as they simply are not true.
Whether you insist your kids wear helmets or not isn’t for me to decide. What I will say is this: get especially younger kids to remove their helmets the moment they get off their bikes. Helmet manufacturers (and indeed the slightly modified standard for children’s helmets) explicitly warns against the risk of strangulation. NEVER let your kids onto climbing frames or similar while wearing a helmet – the risk of harm is real and far too big.