How Does a Helmet Work?
A helmet reduces the peak energy of a sharp impact. This requires a layer of stiff foam to cushion the blow. Most bicycle helmets use crushable expanded polystyrene (EPS), the picnic cooler foam. It works well, but when crushed it does not recover. Expanded polypropylene (EPP) foam does recover, but is much less common. Collapsible plastic liner materials recently appeared in Bontrager helmets and are claimed to reduce concussion-level energy. A MIPS slip-plane layer is also claimed to do that. The spongy foam pads inside a helmet are for comfort and fit, not for impact protection.The helmet must stay on your head even when you hit more than once–usually a car first, and then the road, or perhaps several trees on a mountainside. So it needs a strong strap and buckle. The helmet should sit level on your head and cover as much as possible. Above all, with the strap fastened you should not be able to get the helmet off your head by any combination of pulling or twisting. If it comes off or slips enough to leave large areas of your head unprotected, adjust the straps again or try another helmet. Keep the strap comfortably snug when riding. The straps hold your helmet on, not the rear stabilizer.
How To Choose A Cycle Helmet
If you do choose to wear a helmet, there are a lot of options out there. The most important factor is comfort – you will be wearing this thing hopefully every time you ride your bike, so making sure it fits is paramount. After that, try and work out what suits you in terms of price point, the amount of ventilation it offers, even weight and aerodynamics – this becomes more of a consideration on higher end helmets.
Types of Bike Helmet
While you can spend generous three-figure sums on a helmet, you can get a decent and certified lid at an accessibly low price. Most bike shops will carry a range of helmets at different price points.
At the entry-level end of the scale, most helmets will be fairly uniform and multipurpose. As you go up in price, helmets become much more specific for different types of cycling, and the various disciplines’ comfort and protection requirements.
Skate helmet / park helmet
These helmets tend to have a rugged, simple construction, with a hard outer layer and a foam inner layer, and low coverage over the head. They usually have few or no ventilation holes, so they’re fine for hanging out in the park or for shorter commutes, but will get a little hot on longer rides or when exerting lots.
They often don’t have a huge amount of fit adjustability, relying instead on using different thicknesses of foam inserts.
Commuter bike helmet
While most helmets will work for a commute, there are some helmets specifically designed for this purpose Immediate Media Co.
Most bike helmets are suitable for commuting, though you can get ones specifically aimed at commuters and urban riders. These range from basic, vented helmets, through to ones that include integrated lights and even stowable waterproof covers.
Some commuter helmets are styled more like skate lids, with a solid outer layer and few ventilation holes, which has the added benefit of helping to keep the rain off your head if the weather isn’t great. Some come with integrated peaks and removable liners, and others even have integrated lights.
Road bike helmet
The POC Octal road helmet is designed for optimum air flow while road riding Colin Levitch / Immediate Media
The focus in the design of road helmets is threefold: to create a helmet that’s lightweight, as aerodynamic as possible, and allows plenty of ventilation to keep the rider’s head cool. Road cycling helmets tend to sit close to the head with many air vents.
As the price goes up, the weight goes down as a general rule, and the the ventilation becomes more sophisticated with internal channels incorporated to allow air to flow over the rider’s head and vents at the rear.
Some road cycling helmets will include features such as slots or magnetic catches to allow you to rest your sunglasses on them, or removable plastic shells to increase the aerodynamic properties of the helmet.Source
How Much is your Head Worth?
Almost half of bikers surveyed owned two or more motorcycle helmets, in different styles including flip face, but 75% still preferred the full face option.
Bicycle Helmet Infographic
Anatomy of a good bicycle helmet