The core of every helmet.

The core of every helmet.

Every bike helmet has an EPS inner shell. It is the invisible heart behind the outer shell and takes on the crucial task in a crash: it absorbs the impact energy before it reaches the head. Without a well-engineered EPS inner shell, no helmet is truly safe, no matter how good it looks from the outside.

At KED, EPS is not an interchangeable standard component but an actively designed element of the helmet construction. How the EPS inner shell is shaped, processed and joined to the outer shell largely determines the protective performance, weight and wearing comfort of the finished helmet.

What is EPS?

EPS stands for expanded polystyrene, a foamed plastic that consists of around 98 percent air. This structure makes it exceptionally light and, at the same time, very well suited to absorbing energy. On impact, the EPS foam structure deforms in a controlled way and absorbs kinetic energy instead of passing it directly on to the skull.

That is why EPS has been the standard material for helmet inner shells in almost all protective helmets for decades: bike, ski, motorcycle, riding. The challenge lies not in the material itself, but in precise processing and construction.

How EPS works in an impact

  • Energy absorption through controlled deformation

    When the helmet hits a hard surface, the EPS inner shell deforms. The small air chambers in the foam collapse and convert the kinetic energy of the impact into deformation energy. This significantly reduces the peak force reaching your head. This process happens in milliseconds and is irreversible: an EPS helmet that has taken a hard impact is spent and should be replaced, even if it looks undamaged on the outside.

  • Why density is crucial

    Not every EPS inner shell is the same. The density of the foam determines how much energy is absorbed and at which force threshold deformation begins. A shell that is too soft deforms too early, one that is too hard gives way too little. KED develops the EPS geometry specifically for the safety requirements of each model.

  • Ventilation as a design task

    EPS inner shells need channels for air circulation. The more and the larger these channels are, the better the ventilation, but the less material remains for the protective structure. This trade-off is one of the central design challenges in helmet construction.

How KED works with EPS

  • Produktionsschritt Schäumerei

    Foaming in Germany

    For KED helmets with Made in Germany production, the foaming of the EPS inner shell takes place in Freiberg am Neckar. KED controls this critical manufacturing step directly, without external supply chains, with its own quality standards.

  • EPS as the basis for In-Mold and maxSHELL

    EPS as the basis for In-Mold and maxSHELL

    The way the EPS inner shell is joined to the outer shell is what distinguishes the two main KED technologies: with In-Mold, the outer shell is bonded to the EPS inner shell during the foaming process itself. The result is a seamless, high-strength unit with very low weight. With maxSHELL, the EPS inner shell and outer shell are permanently joined after foaming using a special bonding process. The focus is on a robust, elastic sandwich composite. Both technologies build on a high-quality EPS base. Without precise foam geometry and a controlled manufacturing process, neither In-Mold nor maxSHELL would develop their full properties.

  • Innenansicht eines KED Helms mit Polsterung

    EPS and RIB-CAGE

    The RIB-CAGE system adds rib-shaped reinforcement elements to the EPS inner shell. These take on load-bearing tasks where large ventilation openings remove material. This allows the EPS inner shell to be generously ventilated without structural compromises.
What makes a good EPS inner shell

What makes a good EPS inner shell

For buyers, the EPS inner shell is invisible. But it helps determine everything you can feel: how light the helmet feels. How well it cools. And how reliably it protects when it matters.

A well-engineered EPS inner shell is precisely molded, evenly foamed and accurately bonded to the outer shell. Exactly this care is the difference between a helmet that meets the standard requirements and a helmet that goes beyond them.

What is EPS in a bike helmet?

EPS stands for expanded polystyrene, a lightweight foamed plastic that absorbs energy on impact. It forms the protective layer inside the helmet.

Why does a helmet need to be replaced after a hard impact?

Because the EPS inner shell deforms permanently on impact and loses its ability to absorb energy, even if the helmet looks undamaged from the outside.

What is the difference between In-Mold and maxSHELL?

Both bond the EPS inner shell and the outer shell into one unit, but in different ways. In-Mold happens during the foaming process for a seamless, very light result. maxSHELL joins both parts after foaming through bonding for a robust, elastic combination.

Does KED produce the EPS inner shell itself?

Yes, for the Made in Germany helmets, the foaming of the EPS inner shell takes place directly in Freiberg am Neckar. This is a central part of KED's German manufacturing depth.

How does EPS affect the weight of the helmet?

EPS consists of around 98 percent air and is therefore extremely light. A well-designed EPS inner shell contributes significantly to keeping a helmet pleasantly light despite a high standard of protection.

Other technologies in KED helmets