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New tech could soon replace conventional helmet liners

Published: 10 September 2019

Updated: 10 September 2019

A major breakthrough in helmet safety could save your skull in a crash and keep your head cooler than current lids.

Virtually every motorcycle helmet currently uses an EPS (expanded polystyrene) liner. But now there’s a new product that claims to be safer, more robust and better ventilated.

EPS is made by taking tiny polystyrene balls (often only 1mm across) and chemically expanding them up to 40 times their original size. This allows them to be shaped in a mould and gives them a remarkable ability to absorb impact. When you crash, the EPS liner is crushed, reducing energy transfer to the brain.

But EPS has some drawbacks, not least that it’s affected by temperature, has a relatively short shelf life and is solid, so can’t let air through. Now, though, there’s a new alternative.

Layers upon layers

Debuting in Klim’s new F5 adventure helmet, Koroyd is a new type of liner. Instead of slabs of polystyrene, Koroyd is made up of hundreds of tiny tubes. These tubes are made from short sections of a plastic polymer, which are extruded to create tubes 3mm-6mm in diameter depending on application.

These tubes are then stuck together to form a honeycomb, which is then cut into sheets and placed inside the helmet. In the event of an impact, the tubes deform to absorb the energy just like an EPS liner, but in low impact situations the Koroyd tubes are able to bounce back.

They can also deform at a higher rate, up to 84%, whereas typical EPS liners reach maximum absorption around 60%. There are other advantages, too.

The price you pay

EPS is quite susceptible to chemical damage, which is why every helmet should be replaced after five years. But Koroyd is unaffected by most chemicals and also performs consistently across a wide range of temperatures.

Another benefit is the cooling effect of the tubes as air can run straight through the panels from front to back, increasing airflow to the head and aiding cooling.

Koroyd’s lead scientific consultant Dr Priya Prasad has been studying automotive accident data for 40 years and said: "The current safety standards are over 20-years-old and it’s time to put helmet protection at a higher level using the latest technology. This new liner is a major step in the right direction that will improve rider safety significantly."

However, Koroyd’s new tech comes at a price. The Klim Krios Pro with Koroyd costs £525 compared to £375 for the standard model, while the Koroyd F5 is £499 to the standard model’s £399. But you get a safer, cooler helmet that should last longer and isn’t rendered useless by a minor knock.

A detailed view of the Klim helmet lining


Klim F5 helmet explored

  • Small walls Although double-skinned, the tubes' wall thickness is just 0.09mm, meaning 90% of the structure’s surface area is air.
  • Safety first Koroyd claim that in some accidents, their liners are able to absorb 30% more energy than conventional EPS foam liners.
  • Rebound As the polymer is elastic, unlike foam, a low impact (such as dropped helmet) shouldn’t reduce protection in a crash.
  • Cool runnings Compared to a standard EPS liner, Koroyd claim that their system results in a head that’s nearly 30% cooler.
  • High cost This lovely new tech costs, however, with Koroyd-equipped products costing around 25% more than standard EPS foam.

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