New cycle helmets emit stench if they need replacement

Remorseless German boffins have come up with the greatest boon to humanity since self-warming hand cream: they have invented cycle helmets which begin to smell disgusting once they need to be replaced.

Many cyclists like to wear helmets in order to protect the bonce in the event of a mishap. The cheapest and lightest type of bump-hat - thus the most commonly used - uses a foam-like substance which offers excellent impact protection, but only once. If such a cycle helmet is damaged, for instance by being dropped, it will not work nearly as well in a traffic accident; thus it should be replaced.

But in many cases a light, glancing bonk doesn't actually affect the integrity of the helmet. Naturally users are reluctant to shell out on a new one if this is actually unnecessary. But how to know?

Enter the boffins of the Fraunhofer-Institut für Umwelt-, Sicher- heits- und Energietechnik (UMSICHT), in Oberhausen. They have devised a crafty method of sealing up tiny pockets of what they refer to as "odoriferous oil" in the structure of a cycle helmet. Given a light knock, nothing happens: but a bump strong enough to affect the helmet's effectiveness will rupture the cells and release the stinky oils, informing its owner in no uncertain terms that it's time to get a new one.

Minor damage creates only an unpleasant niff, seemingly, but "large cracks really cause a stink" according to a statement issued by UMSICHT.

"Cyclists often replace their helmets unnecessarily after dropping them on the ground, because they cannot tell whether they are damaged or not," explains Doktor-Ingenieur Christof Koplin of UMSICHT. "The capsules eliminate this problem. If cracks form, smelly substances are released."

Koplin believes that the pong-titfer technology could also be used in industrial hard hats, motorbike helmets, pressure hoses and most other applications where an early warning of material deterioration would be useful. ®