The life-saving spring in airbag bicycle helmets

Concussion is one of the major causes of brain injury. Hence the need importance of a helmet for cyclists. But airbag technology specialist Hövding believes that the world’s safest bicycle helmet may not be a helmet at all. In 2016, a scientific research of Hövding’s airbag technology was conducted and the test results showed that Hövding’s unique design – an airbag that in the event of an accident expands to become both thicker and softer than a traditional helmet – reduces the risk of concussion up to eight times and almost completely eliminates the risk of skull fracture.

The airbag is designed like a hood and made in an ultra-strong nylon fabric that won’t rip when scraped against the ground. Hövding protects nearly all of the head, while leaving the field of vision open. The inflated airbag covers a much larger area than a traditional cycle helmet and is designed according to current accident statistics. To date, a total of 185,000 Hövding helmets have been sold, in 16 markets across Europe and Japan.

Components from Lesjöfors are often key parts in products that demand high safety, strength and functionality. When the third generation of the Hövding airbag bicycle helmet was being developed, the makers therefore turned for assistance to Lesjöfors. They needed help and support in the design and material choice for both a wire form for the airbag’s activation mechanism and a spring clip, from the leaf spring range. The leaf spring is required for fixating the gas generator that inflates the airbag in the event of an accident.

The challenge was to develop two components that would work well mounting wise and at the same time meet the requirements for strength and retained functionality in different weather conditions and user situations – for example, if the cyclist accidently drops the product into the ground.

“At an early stage, we could study the design drawings of the desired functionality of the springs. We immediately saw that the wire form for the activation mechanism best could be manufactured by our factory in Nordmarkshyttan, so we involved them, while the leaf spring was perfect for our operation in Värnamo,” says Johan Gannerud, technical sales at Lesjöfors Banddetaljer.

While engineers in Nordmarkshyttan improved the wire form further, a close collaboration process began for developing the leaf spring. The two engineering teams discussed drawings, tried different materials and thicknesses and carried out rigorous testing. A handful of prototypes with different contours, thickness and tensile strength eventually came down to one clip with all the desired characteristics.

Hanna Risén, mechanical design engineer at Hövding comments on the collaboration: “Hövding presented an initial drawing with specific design features and functionality of the leaf spring. Lesjöfors was a great speaking partner and we got superior support in our collaboration including flexibility and expertise from prototype and tool makers.”

Production of both wire form and leaf spring started in the first half of 2019 and so far, the both factories have delivered about 60,000 items. Marie Hult Johansson, strategic sourcing at Hövding comments on the process: “Despite a very hectic time period right before summer holidays and an overall tight schedule, communication and deliveries from Lesjöfors have worked out flawless. We look forward to our continued collaboration.”

Jan-Eric Nordh, plant manager at Lesjöfors Industrifädrar in Nordmarkshyttan, is happy for Hövding’s success and anticipates a great future for the rapidly growing company: “We are proud to contribute to such an innovative product that saves lives all around the world. This project is also a very good example of how we work together within our group for an optimal solution for the customer.”