Not all helmets are made the same. In a previous article, I discussed the 6 different styles of helmets. Today I’ll be discussing the different materials helmets are made of, and how they protect your head.
All helmets are constructed in the following layers;
- Rigid outer shell
- Impact absorbing liner - generally made of EPS (Expanded polystyrene)
- Comfort liner which also ensures the correct fit of the helmet
Side cut of a motorcycle helmet
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Break down of what a top of the line Fly Racing off road helmet looks like
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There are 4 basic materials that helmet shells are made of
- Plastic/ABS
- Fiberglass
- Carbon fibre
- Kevlar/Dyneema/Aramid
There are helmets made of 2 or move of these materials woven together. They are called Composite helmets.
While some helmet materials protect your head better than others, helmets can be quite expensive. Helmet prices range from as little as $70 all the way up to $2500. Not everyone can spend thousands of dollars on a helmet, and not everyone needs to. Keep in mind, no matter what a helmet is constructed of, they all meet a safety standard, and will keep your skull in one piece.
Plastic Based Helmets
There are two basic types of plastic materials used to construct motorcycle helmets - thermoplastic and thermoset resin.
Thermoplastic helmets do not require a hardening agent, and therefore can be melted down and reshaped without chemical decomposition, leading them to be able to be recycled.
Thermoset resin helmets do require a hardening agent.
While plastic helmets do provide good rigidity and flexibility, they are not as strong as their woven counterparts. This leads manufacturers to create plastic helmets larger and heavier. However, plastic helmets come with a lower cost. Upon impact, plastic allows the force of the impact to travel through the helmet easily. This can result in a good brain rattle, and you don’t know what part of your head you may hit.
Composite helmets
Composite fibre helmets are constructed by weaving, or criss-crossing different fibre strands together. Manufacturing composite helmets require more materials and labour, causing them to be more expensive than their plastic counterparts.
Technically, most helmets are composite helmets.
Fiberglass Based Helmets
Fiberglass is inexpensive, lightweight and quite strong - a great combination when creating a motorcycle helmet. The lightest helmets out there will be composed of either Fiberglass or carbon fibre.
The downside to Fiberglass is that it can be quite brittle, shattering upon impact. This is ok when the rider only impacts the ground one, as the impact absorbing liner then does it part in compressing and absorbing the force of the impact. However if the riders head hits the ground again, harm could be caused to the rider. This is why Fiberglass tends to be used in conjunction with other materials to create the safest helmets.
Raw fiberglass
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Stages of a fiberglass helmet being made
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Carbon Fiber helmets
You’ve probably heard about carbon fiber. It can also be woven into different patterns depending on the desired final look, causing people to add it to nearly everything they can! Often used as apart of additions to cars and motorcycles such as panels and rims, it is also quite useful in the creation of motorcycle helmets.
Carbon Fiber is extremely lightweight (lighter than fiberglass) and strong, as well as quite resistant to pressure and compression. Such helmets are able to withstand impact, and not shatter or crack. Carbon Fiber allows the force of the impact to be spread over a larger area of the helmet, allowing more of the impact absorbing liner to do its job. This is why Carbon Fiber is used in racing helmets.
The one downside to Carbon Fiber is that it is more expensive than the other materials that are used in motorcycle helmets due to higher production and manufacturing costs. Therefore it is often combined with other materials such as fiberglass and kevlar.
Carbon Fiber sheets
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A Carbon Fiber Skin Shark Spartan GT helmet
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Kevlar/Dyneema/Aramid
Yes, we’re talking about the material they put in bullet proof vests, although they are manufactured differently, so don’t expect your helmet to stop a bullet.
You’ll also see Kevlar in motorcycle jeans, as it doesn’t tear easily and is abrasion resistant, making it perfect for incidents involving a rider sliding down a road.
Kevlar is actually a brand name, like Esky, and was developed by DuPont. Kevlar has an aramid type fiber weave base. This material used in Kevlar helmets is produced with the same weave methods as fiberglass ones, then mixed with a very strong plastic compound.
While Kevlar is quite strong, it does not hold up well against compression. This is why Kevlar is typically added to carbon fiber helmets to increase overall tensile strength, while the carbon fiber is there to counteract Kevlars weak compression rate.
Kevlar Fibers
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Kevlar Sheets - just like to what is used in Kevlar jeans
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All in all, a composite helmet of Fiberglass, Carbon Fiber and Kevlar is the best makeup of a helmet. You never know what part of your head you may hit, so a helmet that spreads the force of the impact is your best bet. However, even the cheapest helmet is better than no helmet.
Dress for the slide, not the ride.
Ride safe and have a good one!
Got questions? Send me an email at webshop@bikebiz.com.au
Prue Mottram
Published
January 24, 2020
