What does a motorcycle helmet actually do?


Motorcycle helmets are mandatory for motorcyclists across all the states and territories of Australia, and for good reason too. Research suggests that without a helmet, a rider involved in a crash is 40% more likely to sustain a fatal head injury, but a motorcyclist who is wearing a helmet is 29% less likely to die in a crash.

So what’s in a helmet that can make such a crucial difference in the event of a crash or incident, and what does it do to protect your head?

What’s a helmet made out of?

A motorbike helmet is typically made of four components; a rigid outer shell made out of fiberglass (possibly reinforced with Kevlar or carbon fiber), an inner layer of crushable foam, comfort padding, and a retaining system, usually in the form of a chin strap. See below for a quick table on the crucial elements of a motorcycle helmet:

Element of helmet protection Purpose
Rigid Outer Shell Spreads kinetic force generated by impact, will crack if force is too great to reduce energy
Inner Liner Absorbs kinetic forces that could not be stopped by rigid outer shell
Comfort Liner Provides comfort to the rider and an additional, marginal layer of protection.
Retaining system Chin straps to fasten the helmet to the wearer’s head.

What’s the point of these parts?

The comfort padding plays little to no role in protecting your head in a crash, but the other three parts of the helmet each play their own crucial part in reducing the chances of you sustaining a seriously nasty head injury.

The helmet as a whole is designed to distort and crumple, which will (ideally) expend at least some of the energy otherwise destined for the motorcyclist’s skull. It is designed to take the force from the initial point of impact and redistribute it around the entire helmet, to reduce the chances of the initial impact causing serious injury or death.

The rigid outer shell is there for two main reasons; to prevent penetration of the helmet by a pointed or jagged object, and to protect the inner liner, which requires support and structure, lest it disintegrate due to abrasion.

The inner liner of foam is designed to crush on impact, extending the stopping time of your head by about six thousandths of a second. This significantly reduces the peak impact to the brain, which can be the difference between life and death. Thicker foam is better, as it gives your head more space and time in which to stop.

The chin strap is simply there to ensure that your helmet stays firmly on your head in the case of a crash, so that your head is fully protected from the start to the end of the impact.

You might be of the school of thought that helmets are ‘unnecessary’, or ‘too expensive’, but when you really think about it, what’s worth more; the relatively small amount of money you’ll spend on a helmet, or your life?

Head injuries: what you should know

You may have seen the blockbuster movie Concussion starring Will Smith, which details the effects of repeated blows to the head in American Football. While American football is obviously much less impactful than a motorcycle crash to the head, it is important to note that the two areas share similarities.

Concussion explains CTE – Chronic Traumatic Encephalopathy. This is the degenerative disease that stems from a head trauma or repeated blows to the head, days, weeks and years after a head trauma event.

While motorcycle helmets do their best to significantly reduce head trauma and save lives, the ongoing effects of a single accident can be experienced years later. Symptoms include concussion in the immediate hours and days after the event, and years down the track, speech problems and memory loss, among many other symptoms.

You may have seen the boxer who has been hit too many times – “punch drunk” – slurring his words and in a delirious state. These are some of the more immediate effects of CTE, and the same can be experienced after a motorbike accident. It’s important, if after crashing, to immediately discard your helmet and buy a new one, and to monitor yourself for any symptoms of CTE; this could be a life saver.

Overall, helmets when riding a motorbike are mandatory, and have been proven to save lives, so it’s important to wear one – your life could depend on it.

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