The shell is the hard outer layer of a helmet, designed to spread acute impacts out over the rest of the helmet. The shell also holds all the foam together in a crash. This layer, usually made from plastics like PVC, also provides some protection against sharp objects and makes the helmet last longer by preventing abrasions to the liner.
A helmet liner or core is a thick layer of foam. This foam liner is chiefly responsible for absorbing impacts and preventing serious head trauma. The helmet liner is often made of EPS (expanded polystyrene) or polypropylene foam.
There are two main construction methods for creating a sport helmet:
- In-Mold Construction molds the shell and liner together in one process, creating a lighter helmet. This method is common for making bike helmets.
- Injection-Molded Construction bonds a pre-molded foam liner to a separately-molded outer shell. Although this method creates a slightly heavier helmet compared to the in-mold method, it also provides slightly more durability. Many skiing, snowboarding and motorcycle helmets fall into this category.
Helmet Padding and Lining
Most sport helmets feature soft pads and wicking fabric for comfort and/or warmth, which are often removable for washing. These linings are also great for absorbing sweat and customizing helmet fit.
A common design for most sport helmets is a four-point strap system. A Y-shaped strap on each side of the helmet joins below the ear into a main strap that buckles below the chin. All sport helmet straps are adjustable for a proper fit, and most have a quick-release buckle for easy on-off.
Any helmet you buy from a reputable manufacturer should provide adequate impact protection for the activity it’s designed for. United States law requires that all sport helmets meet minimum CPSC (Consumer Products Safety Commission) safety standards. One way to be sure you purchase a CPSC-certified helmet is to only buy from reputable brands like Giro, Bern and Bell Sports.
Helmets designed for bicycling and other sports are usually not designed for use with motorized vehicles. Any helmet designed for motorcycling, snowmobiling, go-carting or riding ATVs should be DOT certified. Look for a small DOT sticker on the back of the helmet.
The SNELL Memorial Foundation is an independent, not-for-profit organization that tests helmets and has its own set of standards. SNELL tests motorcycle, auto racing, equestrian, bicycling, skate, skiing and snowboarding helmets.
Your helmet must fit correctly for optimal protection. If you buy the proper size, the fit should also be comfortable. Helmet sizes are typically determined by the circumference of the user's head, measured in inches or centimeters.
How to Measure Your Head
Many helmets are designed to fit a range of head sizes. Before you buy a new helmet, determine your head circumference. Use a flexible measuring tape, placing it around the widest part of your head. Place the tape about 1" above your eyebrows. If you don't have a flexible tape, use a piece of string, then measure the length with a ruler.
How to Fit A Helmet
- A helmet should fit snugly, but not be uncomfortably tight or constricting.
- When you shake your head, your helmet shouldn't move very much from side to side, or front to back. If your helmet shifts around on your head a lot, you either need to adjust the fit or you’ve bought a helmet that’s too large. However, it shouldn’t be so tight that it causes uncomfortable pressure.
- Some helmets have an adjustable interior headband, which may include a ratchet or other mechanism to expand and contract the headband. This feature can be used to dial-in a more customized fit.
- If your helmet comes with detachable interior pads, you can add or remove them to customize the fit.
- It’s essential that you properly adjust and buckle your chin strap to prevent the helmet from falling off during a crash. If the strap is too loose, the helmet could slide back on the head, leaving the forehead exposed. Once you get the strap snug, you should still be able to slip your index finger in between the strap and your chin.
- Always help children fit a new helmet and help them put it on. Check to make sure the helmet is not too loose and that the chin strap is securely buckled before your activity begins.
Even a low-speed bike wreck can do some serious cranial damage. There is significant evidence that wearing a helmet greatly reduces your risk of incurring a head injury during a crash or fall. For this reason, some cities actually require cyclists to wear a helmet. Every bike helmet sold in the US is required to meet the certification standards of the CPSC and should have the commission's sticker inside as proof. Perhaps the biggest differences between cycling helmets and other helmets are an aerodynamic design and the addition of air vents.
Types of Bike Helmets
- Road Cycling Helmets tend to be extremely lightweight, aerodynamic and well-ventilated.
- Mountain Bike Helmets usually offer added coverage, especially in the back of the head. Many also have an attached or removable visor.
- Full Face Helmets for downhill MTB and BMX have full faceguards, very similar to motocross helmets. These provide maximum protection during a fall.
Ski Helmets and Snowboard Helmets
Extreme freestyle snowboarders and backcountry skiers aren't the only ones who should wear a ski helmet. Moderate speed combined with crowded slopes, trees and other obstacles equates to a high potential for collisions. Even if you’re an experienced skier or rider, it doesn’t take much to get a concussion from an unexpected fall if you’re not wearing a helmet. Ski and snowboard helmets are also very effective at keeping your head warm.
Ski Helmet Features
- Most modern ski helmets and snowboard helmets are goggle-compatible, but it’s always a good idea to try on your helmet with your goggles before you head to the mountains. Some optics brands like Smith and Anon also make helmets. If you buy a helmet and goggles from the same brand, they will almost always be compatible. However, most goggles will work just fine with most helmets.
- Many ski helmets have built-in vents to keep your head cool. Some helmets even have adjustable vents that open and close, allowing you to adapt to warmer or colder weather.
- Can’t live without your tunes? Several brands offer ski and snowboard helmets with built-in audio systems. Some even allow you adjust the volume, pause the music and answer a phone call with a built-in remote.
As helmet use on ski slopes has increased dramatically over the past few years, ski helmets have also become very affordable. Many basic models can be purchased for less than the cost of a lift ticket at a larger resort. Most ski rental shops also rent helmets for a small daily fee.
Mountaineering and Climbing Helmets
Climbing helmets, which can be worn for rock climbing, ice climbing and mountaineering, are designed to protect your head from falling debris and during a short fall. Climbing helmets offer protection from objects like small rocks and carabiners falling from above. They also provide head protection during a roped fall that may cause the climber to swing into the rock face.
Most modern climbing helmets offer the same foam core construction used to make other sport helmets. Traditional climbing helmets, on the other hand, are sometimes called “suspension helmets,” and are designed like hard hats, with a heavier outer shell suspended away from the head by interior webbing. Climbing helmets from most reputable brands offer impact certification from either the CE (European Committee for Standardization) or the UIAA (Union Internationale des Associations d'Alpinisme), sometimes both. The UIAA is the more rigorous tester of the two, requiring 20% greater impact protection than CE standards.
Climbing Helmet Tips
- Even in summer, mountain summits can be chilly. Winter and ice climbing often involve downright frigid temperatures. Be sure your climbing helmet is roomy enough to wear with a balaclava, if needed. Climbing helmets with rotating disc adjustments are great for climbers because of the regular need to add and remove insulation.
- Longer summits often require setting out before dawn, allowing climbers ample time to get off the summit before bad weather rolls in. Also, some climbing routes end up taking longer than expected, which means descending in the dark is always a possibility. For these reasons, choosing a climbing helmet with headlamp-attachment clips is always a good idea.
Every kayaker who hits the whitewater knows how deadly a roll can become when there's a rock or log lurking under the surface. Whenever you boat on the river or along a rocky shore break, be sure to wear a kayak helmet. Typically designed without air vents, a kayaking helmets usually have breathable foam linings to help keep you cool and a sun visor so you can see what lies downriver.
Multisport helmets have no season. Most are designed for skating and cycling in summer, and also for snowboarding and skiing in winter. Many multisport helmets convert from winter to summer sports simply by adding or removing a warm inner liner and exposing air vents.
Most helmets for motorcycling, motocross, ATV-riding and snowmobiling protect the entire face, as well as the head. Some have a transparent face shield that flips up and down. Others have an open space for goggles or sunglasses. Motorsports helmets are thicker and heavier than sports helmets, and should always be DOT approved.
Helmets are built tough, but they can still suffer from wear and tear over time. Store your helmet out of the sunlight and keep it inside a bag to protect it during storage. Also, before each use, give your helmet a quick once-over.
- Inspect the helmet's liner foam to be sure it’s not seriously dented, misshapen or compressed. Be sure it’s securely encased within the shell.
- Check the helmet shell for cracks or other weak points.
- Make sure the chin buckle or strap is working properly.
- Examine the strap webbing where it attaches to the helmet for tearing or fraying.
Helmets are designed to protect the head during a single crash, and should always be retired after absorbing a moderate or heavy impact. If you’re ever involved in a fall or crash and your helmet contacts the ground or another hard surface, you should retire the helmet. Even if the exterior shell appears largely undamaged after an impact, the structural integrity of the interior foam could still be weakened or damaged, which means the helmet will not provide the same level of protection during a second impact.
Because the sun's UV rays can weaken helmet materials over time, you should replace your helmet periodically. Most lightweight bike helmets and similar in-mold helmets need to be replaced about every five years. Sturdier climbing and snowboarding helmets may last a little longer than bike helmets, and can probably last for up to 10 years, if undamaged. Read and follow the manufacturer's suggestions for helmet replacement.