How Bicycle Helmets Work - What Features do You Need?
Bicycle helmets are a very important element of cycling; however, it can often be quite daunting when deciding which one is right for you. Recent developments in technology now mean there is a myriad of different elements and options to choose from, each with their own pros and cons.
How They Work
A standard bicycle helmet protects your head in three main ways. Its most basic purpose is to act as a barrier between your head and an object, with the hard shell of the helmet protecting you from direct contact against any sharp or hard objects. It also further protects your head by spreading the force of any impact over a larger area, therefore reducing the pressure felt on the head. Finally, a helmet slows the deceleration of the skull during an impact to reduce the chance of brain injury and skull fracture.
Bicycle helmets are generally made from EPS (Expanded Polystyrene) foam with a hard plastic shell on the outside. The EPS foam is there to absorb the forces by deforming during an impact, however, once deformed the foam becomes more dense or even cracked, meaning the helmet is no longer effective and will need replacing. The hard plastic shell is then either glued onto the EPS foam (for cheaper helmets) or, more often, is formed during the moulding process. On more expensive helmets there is also a hard plastic ribbed cage on the inside to hold the helmets shape in the event of a multiple impact collision.
There is a variety of different helmet designs from different manufactures to suit your needs. All helmets will have some for of adjustable strap and fitting system inside the helmet along with padded inserts for comfort. It is important to make sure the helmet is the correct size and fits well, not only for your comfort, but also to ensure it is in a suitable position for protection and secure in the event of an impact.
It is also vital to make sure the helmet is in good condition to provide you the necessary protection. Once a helmet has had an impact the EPS foam will have been compressed and therefore lost its shock absorbing properties. It may not always be clearly visible and there may even be cracks hidden by the shell or internal cage and lining. UV rays also slowly degrade the plastic and EPS foam causing it to become more brittle over time. Therefore, it is recommended to replace your helmet every two to three years, even if it has not had any impacts. Some manufacturers will even offer a small discount on replacement helmets after a crash!
Bicycle helmets must adhere to the current European standard in order to be sold within the European Union. This standard is currently EN 1078:2012 and will always be visible on a sticker within the helmet. In order for a helmet to comply to this standard it must undergo a number of tests looking into the construction, field of vision, shock absorption and retention system. This involves impact tests using a drop rig onto both flat and kerbstone anvil surfaces from a height or 1.5m where the resulting deceleration of the head within the helmet must not exceed 250g (where g is the acceleration due to gravity, 9.81m/s). There are many other factors stipulated within this standard which helmets must meet, so you can be sure that the one you buy will be up to the job!
Recent developments in helmet protection systems have added many more options to the market, giving consumers more choice and better crash protection.
One of the more prevalent of these new developments is MIPS. This is a "Multi-directional Impact Protection System" that has been designed to add protection in helmets against the rotational motion. The is is achieved with a thin, low-friction layer mounted within the helmet between the shell and inner liner. In the event of an impact the helmet will then move independently of your skull therefore reducing the rotational forces and angular acceleration on the head and brain.
As mentioned above all helmets will be tested to ensure they meet the necessary standards, however, these tests only test helmets with vertical drops whereas in reality most collisions will be at an angle. MIPS has been scientifically proven to reduce skull and brain injuries. This can be seen in the image on the right showing the strain level in the brain with and without MIPS which was gathered from a crash test dummy.
Another option for protecting your head rather than the standard helmet comes from the Swedish company Hövding. They have created an innovative new design which means you no longer have to wear a helmet but just a small collar. This collar contains an airbag which inflates into a hood to cover your head in the event of a crash. Within the collar is the power unit with sensors and a rechargeable battery. This sensor measures the deceleration of the head and along with a complex algorithm developed from data taken from normal riding situations it deploys the airbag during a crash situation. The airbag inflates in 0.1 seconds and delivers 3 times better shock absorption than a regular bicycle helmet.
Research at Stanford University was conducted to investigate the level of protection provided by Hövding compared to a standard bicycle helmet. It was found that the thickness and stiffness of the Hövding helmet was "near perfect" in terms of protecting against concussion and head injuries caused by accidents. The research concluded that the Hövding airbag provides up to eight times better protection than a traditional bicycle helmet.
This August Hövding have announced reaching a massive milestone with a total of 100,000 airbag units sold. Fredrik Carling, CEO of Hövding commented: “Since the beginning of 2018, we have sold as many Hövding airbags as we did in the last five years combined. We are incredibly proud and happy to announce that there are now over 100,000 cyclists protected by Hövding’s unique technology".
- Rob Day