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Bicycle Helmet Safety Institute



The Kranium Helmet




Summary: We get emails from people asking if we know about the Kranium. We consider the design unproven, but it would be the first really recyclable helmet, and the inventor says it could be customized for head shape, a real advantage.




At the London Cycle Show in 2011 inventor Anirudha Surabhi introduced a prototype of a radical new helmet design. The Kranium has a shell like a conventional hard shell skate style helmet, but instead of a conventional foam liner it has interlocking rows of corrugated material that look like cardboard.

Kranium helmet liner from Abus.

Despite what you may read in blogs, the Kranium is not made from "the same cardboard you find in boxes at the supermarket." Helmet standards require testing a sample after four hours of submersion in water, so the inventor says the material has been coated to be waterproof and can survive seven days of submersion.

The Kranium liner is made of a paper-based material, but the shell is normal plastic made of petroleum raw material. It might have the advantage of being recyclable. Foam helmets are not, and are an ecological disaster, because EPS will last for centuries in a landfill. But since the corrugated material in the Kranium cannot be cardboard because users must be able to ride in the rain with it, the liner has to be made with corrugated plastic or cardboard material impregnated with a polymer of some kind, and that would probably render it non-recyclable. In addition, the only helmet on the market at present with the honeycomb liner also has an EPS liner.

The Kranium's inventor says it can be custom made, fitted to each head. That would be a boon to those with odd head shapes, and a big advantage for people with very very large heads who can't find helmets at present. But as skiers discovered with custom-foamed ski boots, the service to perform the custom fitting work is always much more expensive than the materials. EPS is nearly as cheap as cardboard anyway. And it would be difficult to certify a custom helmet to a standard, since the certification process requires testing different production samples under ambient, hot, cold and wet conditions. Users could just snip away at the liner, but the result might be a dangerously underperforming helmet, with no way to know that until a crash.

There is considerable assembly required to put a helmet liner together with the corrugated pieces, perhaps raising the final price above a conventional foam helmet. Quality control would be difficult to assure compared to foam. And explaining to a jury why your "cardboard" helmet did not prevent a head injury could be a problem for manufacturers.

The designer understands that shared bicycle programs have a helmet problem, and says the Kranium could be dispensed from vending machines. But a conventional foam helmet can be too, and custom fitting would not be practical in a vending machine.

The first implementation of the design was shown at fall, 2012 bicycle industry trade shows by Abus, a German manufacturer. It was called the Kranium Ecolution, but has been renamed the Performance. It is a hybrid design, with one layer of corrugated material strips next to the hard shell and one layer of regular EPS foam between that and the head. Abus says the EPS foam is recycled. The Performance retails for 80 pounds in the UK.

Kranium helmet.

Kranium helmet interior showing liners.

The photo above shows the two layers of the Performance's liner. Through the vents you can see the corrugated material forming the layer between the shell and the standard EPS liner.

More info and videos

The inventor has a very interesting technical paper out that includes standard lab test results to a portion of the European helmet standard. The results are only for an ambient helmet and only on the flat anvil, testing the top (where virtually nobody hits) and two spots on the right and left front corners. The top results are impressive, but the sides are very little better than (the same?) helmet with an all-EPS liner. We think the angle of impact might have a big effect on the cardboard's ability to perform due to the alignment of the cardboard strips. The inventor says his liner is designed to flex in some locations and be stiff in others until the crush begins. There is no multi-impact data. Here is a better Web site for the kranium, with photographic explanation of the construction details and a nice video of the hand assembly process. And here is a video explaining how the inventor's thought process worked.

All in all, the Kranium deserves high marks as a design project that comes at the problem from a completely different angle, but we don't think you are likely to see a helmet brought to market with that design. The version Abus is marketing is a hybrid using EPS, and not designed to meet the US standard. More serious alternatives to foam are already performing in some football helmets and the Seven System in Cascade's lacrosse helmets. They are using plastic forms that deform at a controlled rate in a crash to replace the EPS entirely. Like the Kranium, they perform well at lower impacts, but they don't meet US bicycle helmet impact standards.


This page was last revised on: March 31, 2013.

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