With each new year, we see new technology and new design concepts hit the cycling world, most notably in the realm of bike frame design and component upgrades and safety equipment. Over the past decade, helmets have undergone drastic design changes that have redefined how we ride with head protection, making riders both safer and more comfortable than ever. While buying a helmet online may leave you feeling uncertain in how it will fit your needs, this definitive guide to helmet sizing and helmet style will hopefully give you the confidence you need to lock up the best bike helmet for you.

STOP! Chances are you are either in the market for a new helmet or depending on how old yours is, you might need to be. Take this quick second to measure your head using a measuring tape, or length of string and marking and measuring the string after. Since most companies deal in millimeters I suggest you make a note of your head in millimeters and stash it somewhere so you don’t forget! Don’t stress too much about finding the right helmet in your exact size, as most if not all helmets come equipped with a retention system that allows riders to adjust the fit of their helmets on the fly, as well as allow for a greater range of fit options for different head sizes as well as adjustable chin straps to further tailor the helmets fit.

Types of Helmets

With several unique styles of riding comes the necessity for several unique styles of helmets, all serving different purposes, or at least emphasizing different benefits over others. Typically road bike helmets emphasize a lightweight frame, aerodynamics, and minimalism while mountain bike helmets often choose to cover more surface area of the head and are often heavier as a result. Plenty of great helmet companies challenge the balance of lightweight and protective every day, which makes for a diverse catalog of excellent lightweight and protective helmets. Because different riding styles require different safety standards, not all helmets can be used for all riding styles, and some are certainly more equipped for impact than others.

Road Bike Helmets

Riding on the road means the rider needs to be comfortable as well as protected in the event of an accident. Because of the more direct headwinds that occur for road cyclists, helmet manufacturers are constantly working to design helmets that are more aerodynamic and take away as little as possible from the rider's performance. Another key focus of road bike helmets is ventilation and ensuring that the rider stays cool and comfortable during their ride. As a result, many road bike helmets have large openings or “scoops” for ventilation to maximize efficient airflow. Depending on your focus of road riding, like triathlons or crit racing, your helmet emphasis will likely align with your bike's emphasis. Since triathlon bikes are typically focused on lightweight aerodynamic synergy, so too are the helmets focused on aerodynamic efficiency in the lightest possible package. Bikes and road races that emphasize light weight and efficiency will similarly correlate most often to helmets that emphasize lightweight comfortability as well.

Triathlon/Time Trials Helmets

With a steadfast commitment to aerodynamics, these helmets often have a foiled design to maximize efficient airflow over the helmet and reduce drag on the riders head. Due to the foiled design they might not be ideal for everyday riders, but what they lack in practical style they more than make up for in technical functionality and efficiency.

Climbing/Crit Helmets

This helmet style is typically what most people associate road bike helmets with visually. They offer a balanced mix of aerodynamic and weight-saving efficiency. Because they are often less focused on the direct drag on the rider, they don’t put the same emphasis on the foiled design as time trial or triathlon helmets do, but they still strive for aerodynamic efficiency nonetheless.

Mountain Bike Helmets

While mountain bike helmets are still designed to keep riders comfortable and aerodynamic, there is a shift in most mountain bike helmets to focus the design on greater skull coverage and, recently, cross-discipline versatility. Mountain bike helmets are constantly being redesigned to maximize comfort, and now there are models that offer riders over ear protection as well as removable chin guards that can be stowed away and attached as the trail changes. There is a diverse range of designs for mountain bike helmets due to the different disciplines in riding such as cross-country, enduro, and downhill or freeriding. Cross-country helmets sometimes resemble road bike helmets with their emphasis on being lightweight and well ventilated, while downhill helmets place their emphasis on total head coverage, often closely resembling full face motorcycle helmets.

Cross-Country Helmets

These helmets are typically ridden by riders who are looking to maximize their weight savings, airflow, and aerodynamic efficiency. With helmets constantly pushing the envelope of lightweight packages, there are more and more helmets that can offer great protection while still keeping excess weight off.

Enduro/Trail Helmets

Enduro helmets are perhaps the most versatile and commonly used of helmet styles, as they offer riders both excellent coverage as well as all-day comfort and ventilation. Recently this helmet category has seen innovation that allows riders to easily remove chin guards, as well as helmet frames that offer reinforced protection to riders’ ears.

Downhill/Freeride Helmets

Offering the most protection and coverage as possible are downhill full-face helmets. Because of the dangerous terrain and jumps presented in downhill mountain biking, the protection offered to riders needs to be consummate to the damage they’re facing. This means that downhill helmets have a separate rating relegated to their class, ensuring that these helmets will protect riders in the worst-case scenarios.

Other Types of Helmets

BMX Helmets Born out of a need to protect riders pushing their trick riding abilities, BMX helmets are “bucket” style design helmets that maximize coverage on the front and back of the skull, similar to some mtb helmets and skate helmets. BMX helmets often have fewer ventilation openings in them, although they still maintain some openings to keep riders comfortable. Due to BMX riding typically occurring on concrete or asphalt surfaces, these helmets need to offer complete coverage and as a result, are typically best paired with a supporting anti concussion technology.

Commuter Helmets Similar to BMX helmets, commuter or hybrid helmets often maximize their coverage, as well as ventilation to keep riders as safe and comfortable as possible. Due to the potential dangers with commuting, commuter helmets also need to deliver as much coverage as possible as well as a well-ventilated helmet for daily rides.

Latest Technology

MIPS

Multi-Directional Impact Protection System or MIPS technology is a helmet liner that sits between the rider's head and the outer shell, typically consisting of high-density EPS foam. It’s been proven to reduce the impact that is concentrated from one zone and help spread the impact so that it isn’t as focused, which helps reduce the overall trauma to the rider’s head in a crash. Instead of having a centralized impact location as the helmet receives a concussive impact, the MIPS layer shifts within the helmet, allowing the outer shell of your lightweight bicycle helmet to rotate and disperse impact. This technology has had such a profound impact on head trauma and concussion prevention that it has been adopted across many different sports and platforms. You can find MIPS options for any riding style, and most often than not helmets that aren’t equipped with it already have a MIPS counterpart. Although it may cost a little more, I would strongly encourage everyone to consider buying a MIPS-equipped helmet, or an equivalent helmet technology to give you additional concussion protection.

Removable Chinguards/Chinbar

One of the biggest developments to hit the mountain bike helmet industry lately has been the advent of removable chin bar/chin protection, which effectively converts enduro half-shell helmets into full face helmets. While there are a few designs of this concept being produced by various manufacturers, most notably Giro and Bell, the concept of the removable protection is fairly similar from one brand to the next. The helmet has a chin protector that can be easily inserted into the helmet, as well as easily removed, giving riders comfort during their climbs and increased confidence on their descents. This technology has been a huge step in dual-discipline versatility, allowing riders to push their descents past what they would normally do, due to the additional face coverage. While the chin guard itself doesn’t mean that this helmet is rated by the CPSC to be a downhill helmet, there are downhill-specific helmets that offer the removable chin guard. These would be the only helmets rated for actual downhill riding.

Wavecel Technology

The latest helmet technology released from Trek, Wavecel is an inner-helmet liner that functions similarly to MIPS by allowing the liner to compress and shear laterally separate from the outer protective shell, offering a claimed 48 times greater efficacy at preventing concussions than standard high density EPS foam. While Wavecel is specific only to Bontrager/Trek helmets right now, the technology offers consummate protection alongside MIPS technologies and other additional safety helmet liners. With the ability to disperse significant impact while maintaining a lightweight and breathable composition, Wavecel technology will surely be gaining traction with riders in the coming years.

Koroyd Technology

Koroyd impact protection offers similar concussion reduction technology, albeit in a completely different manner from Wavecel and MIPS entirely. Koroyd protection is a system of high density tubes that are welded together to form a sort of honeycomb layer that absorbs direct and angular impacts with greater efficiency than standard EPS foam. Perhaps the greatest feature of Koroyd is that it doesn’t impact the ability of a helmet to equip MIPS, so you can potentially combine the benefits of both technologies, resulting in the maximum level of performance available.

Hopefully by now you’ve narrowed down your style of helmet, and are looking for options that give additional protection outside of the helmet's hard shell. Safety features like Wavecel, Koroyd, or MIPS all greatly enhance a helmet's safety level, reducing head injuries while striving for all-day comfort and breathability. It’s important to match your helmet with the style of riding you are looking to do, ensuring that your helmet gives you as much protection as possible as well as being designed specifically for the style of riding you are looking to explore.

To explore more Cycling articles as you pursue your journey in the sport, check out the Expert Journal here on Curated.