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What Are Mountain Bike Helmets Made Of?

What are Mountain Bike Helmets Made of

We all know that mountain bike helmets form an important layer of protection for your head. Mountain biking is a sport that has its risks, especially if you crash and tumble down a steep slope. However, even if you only stick to road cycling, you would still risk colliding with other road users, or falling off your bike if you go over a large bump.

Mountain bike helmets are made up of various materials to effectively protect your brain in a crash. According to the Bicycle Helmet Safety Institute, they usually comprise three parts- the shell, liner and straps.

What are mountain bike helmets made of?

The Three Components of Mountain Bike Helmets

Helmet Shells

Helmet shells for the lower price ranges tend to be made out of stamped polyethylene terephthalate (PET) plastic. This is the same plastic used to make bottled water. It may be glued on to the liner, and the outside edge may be taped for esthetics.

Helmets sold at higher price ranges tend to have a high-quality plastic shell, such as polycarbonate. This is to withstand the high heat in production that PET would not be able to. The shell is placed in the mold, while the liner is expanded under heat and pressure. Some advanced production methods can add multiple shell sections, providing stronger helmets.

Helmets for skating, and a number of bicycle helmets, use hard shells made out of polycarbonate or ABS plastic. Older technology in bicycle helmets typically used composite hard shells, adding layers of Kevlar or fiberglass in the epoxy resin.

Helmet Liner

The helmet liner is a foam layer that absorbs most of the energy from the crash. For this reason, it is regarded as the most important part of the mountain bike helmet. Many helmets are molded using Expanded Polystyrene (EPS) foam. Lower-end helmets use standard procedures to mold foam, similar to EPS components of other products. EPS granules, called beads, are placed in a mold. They are then expanded using steam and pressure.

Meanwhile, higher-end helmets make use of additional reinforcements. The main purpose is to create additional vents, and getting the liner to line up precisely with the vents can be tricky. Manufacturers would keep this technology as a fiercely-guarded secret from competitors. Materials such as nylon, metal mesh and polypropylene may be used as reinforcement in the foam.

EPS foams may be made in variable densities in a few layers. This results in softer layers being crushed in smaller impacts, while the harder layers absorb large impacts. Besides EPS, manufacturers have also begun to produce helmet liners using other materials, including EPU or EPP.


Straps are important for securing the helmet to your head. They are usually made of polypropylene or nylon. Straps may vary greatly in their design, finishing, weave and other features. For mountain bike helmets with glued-on shells, the straps are added to the liner, before attaching the shell. For molded in-shell helmets, straps are only attached after the helmet is out of the mold. Usually, the straps will be anchored to the top of the helmet shell after threading through. Hard helmets could have straps attached through riveting.

Some higher-end helmets have a stabilizer piece. This engages your occipital lobe, a bump at the back of the head. Buckles are the final piece of the puzzle. They are usually made of plastic or nylon with a side-pinch release.

Other Components

Some bike helmets have a ring fit system, with fitting pads that can be made tighter or looser. This provides a more comfortable fit, especially if your head is unevenly-shaped. Besides, some helmet models may come with visors, mounts, speakers, earpieces or other accessories.


Mountain bike helmets generally consist of three parts, the shell, liner and straps. Regardless whether you prefer the latest high-end helmet with advanced technology, or just a basic helmet, make sure your head stays protected while riding your mountain bike!

Source: Bicycle Helmet Safety Institute,