Not all motorcycle helmet shells are the same. In fact one of the main factors that affects a helmet price is the material from which the outer shell is made from.
While all helmets that are sold in the UK need to meet the ECE 22.05 safety regulations, some helmets, due to the type of material and quality of production far exceed these standards.
Whilst the materials used in a motorcycle’s shell vary widely, they can essentially be split into two categories; those made from woven-fibres and those made from plastic. Generally speaking, the plastic-based helmets are cheaper while at the other end of the scale, helmets made from carbon fibre tend to be the most expensive.
Carbon fibre consists of minuscule strands of carbon and other organic polymers. Raw materials are made into long strands which are then subjected to high temperatures causing a chemical reaction. This chemical reaction expels the majority of non-carbon atoms within the material, leaving a strong, interlocked carbon fibre as the end product. Carbon fibre can be woven into a mat-like cloth or combined with other durable materials to create a lightweight and incredibly sturdy outer shell for a helmet. Due to its robust construction, carbon fibre is often layered with other materials such as Kevlar, to create a helmets’ outer shell making sure there is enough flex to absorb the impact of a crash.
A composite is a material made up of 2 or more substances. In helmet terms, this often means using carbon, glass or Kevlar fibres. By mixing and layering these fibres, manufacturers can form stronger, more flexible helmets that can withstand impacts and protect your head during an impact.
Fibreglass is made of thin strands of reinforced plastic embedded with glass fibres. Held together with a binding agent, fibreglass, can be woven into a flat mat and moulded to any shape which makes it a perfect material for helmets. Not only is fibreglass flexible, but it is also incredibly lightweight and strong. The flexibility of the material allows the energy of an impact to spread out more evenly along with the outer shell, so less force is transferred to your head. Thanks to their higher quality, fibreglass helmets often carry a higher price tag than the standard thermoplastic varieties.
Kevlar is a robust Aramid-type fibre weave often associated with bulletproof vests. Kevlar was initially developed by Stephanie Kwolek at DuPont in 1965 for use as a replacement for steel in racing tyres. Using the same methods, one would use when making fibreglass, by weaving synthetic fibres before mixing with a plastic compound for binding. The firm heat resistant material has since been used in motorcycle helmets, mainly as a layer within carbon fibre helmets to increase the overall tensile strength.
Plastic helmets often make up the cheaper ranges of helmets; there are two main types used in motorcycle helmet manufacture: thermoplastics and thermoset resins (or Thermo resins for short). Plastic helmets offer the right level of protection needed during an impact but pound for pound; they are less strong than the other composite weaves mentioned above. Plastic outer shells tend to be a lot thicker than their composite counterparts and as a result, they can be heavier.
Thermoplastic is one of the more basic compounds. It is created by heating various oil-based polymers into liquid form before forming into helmet-shaped moulds. Because thermoplastic doesn’t require any additional chemical reactions to cure the mixtures, left alone to harden and set, they can be melted down and recycled, making them extremely affordable.
The other main variety of plastic helmets are advanced thermoset resins (ATR) or Thermo resin as it is often referred to in the marketplace. Thermo resin helmets follow the same process as thermoplastic varieties yet require a curing agent (usually epoxy or polyurethane) to create the necessary chemical reaction for the plastic to harden. Unlike thermoplastics, Thermo resin helmets cannot be melted down and recycled.
Polycarbonate is a thermoplastic made from synthetic plastic resin which contains carbonate in its chemical makeup. Polycarbonate can be used for many products including the outer shells of helmets or their visors. Polycarbonate helmets offer a higher level of protection than other thermoplastic varieties (because they contain carbonate within their makeup).