When buying something we are generally overrun with choices and options. At times this is fantastic however often we are just confused and overwhelmed. What you need is knowledge…knowledge about the product and how it works .
I remember when I first started wearing a bike helmet. I am not sure if these were just playground names or the marketed names for a bike helmet but we called them stack hats or skid lids. Do you remember any other names? Thankfully their social acceptance has greatly improved, helped by helmet laws in many countries evolving to compulsory use.
Bike helmets have come a long way since these first helmets in comfort, style, and how they work. Though we have had many changes the components that make up the helmet and their purpose are still pretty much the same.
All bike helmets are made of three different components.
The shell of the helmet
- The Shell – the outer hard part of the helmet.
What is it made of? A type of plastic. The degree of hardness of the plastic can vary . The skate style helmets generally have a harder plastic than the more classical bike helmet. Alternatively they can be made of a composite (like fiberglass or lightweight carbon fiber.)
Function – The shell holds the helmet together and protects the foam liner. It takes the initial impact and allows your head to slide along the surface preventing the forces involved in abrupt stopping.
Glued and taped on shell
Key point: In the less expensive helmets the shell may be glued to the liner, some are taped around the edges, but not all. In the more expensive helmets the plastic shell is molded to the liner. The later helmet, is stronger though manufacturers take advantage of this increased strength by putting more and larger ventilation holes in the helmet. The harder shells make for a stronger shell but adds weight to the helmet.
Foam liner, see the different shaped foam molds
2. The Liner – the softer inner part of the helmet
What is it made of? Generally a foam called EPS (Expanded Polystyrene). This is where a lot of research and development is focused and we are seeing development of different foams. The foam can have other materials buried within it to help strengthen it.
Function – This is the key part of the helmet, where the energy of the crash is managed.
Key point: All foams immediately or eventually deteriorate under impact. This is why it is suggested you never buy a secondhand helmet and you replace your helmet following impact. Note: there are foams that do not deteriorate after impact and we are starting to see them in the market, but there is still progress to be made.
Technology advances are improving in the world of helmets with the recent introduction of MIPS (Multi-directional Impact Protection System). MIPS gives better protection in sudden angled impacts. It copies or mimics the human brains protection layers – the skull and a layer of fluid underneath it (cerebral spinal fluid) by adding a low friction liner suspended from the interior foam casing by an elastomeric attachment system. What this means is that the MIPS allows independant rotation of the outer helmet. Redirecting impact energy means that less energy is being transferred onto your brain which means more protection.
The Shell moulded to the liner
Shell Taped to Liner
- Straps, buckles and clips. Occipital fastener and internal ring systems.
What is it made of? Nylon, polypropylene and plastics.
Function – To allow adjustment to ensure the helmet fits snuggly to your head and stays there during an impact or multiple impacts (e.g. car and road)
Key points: Check that you can use and manipulate any fasteners easily, and they are strong and hold when pulled/tugged/twisted.
Bike Helmet standards – manufacturers and retailers of bike helmets are required by law to ensure that the bike helmets they make and sell meet a certain standard. The accepted standards vary between countries.
There are a number of different standards accepted in New Zealand and you can check out the different standards, symbols and stickers (see information on cycle safety) for each on the NZTA (New Zealand Transport Authority) website. One of these standards will be displayed on the helmet. This information is also available on this printable provided by the NZTA.
How a Helmet Works – The Bike Helmet Institute shows that helmets successfully reduce impact by dispersing the impact energy. Though we are talking milliseconds the impact force is dispersed over a greater timeframe so the helmet is working to avoid that sudden stopping force on impact that may result in a brain injury.
I hope you will never see a helmet in the same way again. You will now see the shell, see the liner, see the straps and fasteners. Understanding the components of the helmet and how they work gives you the platform for understanding the other goRide stories in the helmet series.
Different types of Occipital fasteners
Peak forces wearing a helmet
Forces dispersed when wearing a helmet.
get Safe and goRide – Helmet components and how they work
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