How To Properly Size A Motorcycle Helmet

Simpson Race Products’ history in helmet development dates all the way back to the late 1970s. Although the company was exclusively focused on Snell-rated auto racing helmets at the time, many motorcycle riders also opted to wear them due to their design and the protection that they offered. In more recent years, Simpson has expanded its development efforts into purpose-built motorcycle helmets that provide riders with everything they need and nothing they don’t.
“What they found was that the auto standard wasn’t really optimized for that type of use case,” says Jamie Beckett, Director of Simpson Race Products’ motorcycle division. “With a race car, you have concerns like hitting crossbar tubes, sharp fixtures in the vehicle, and other things like that which required a lot of attention to penetration protection, which resulted in a thicker, heavier shell. But with motorcycling – especially off-road – it’s more about impact energy absorption. And when we noticed that the Outlaw Bandit auto helmet remained popular among motorcyclists, we knew that we needed to create something that was really designed for riders specifically. So we introduced the Ghost Bandit in 2016, which offered both ECE and DOT motorcycle safety standard certifications, making it a globally-compliant design.”
He compares the change to a purpose-built design to the evolution of safety philosophies in NASCAR. “In the early days, the saying was, ‘When in doubt, build it stout.’ But as the safety technology advanced, they realized that the goal wasn’t to ensure that the helmet was intact after the incident – it was to ensure that the person wearing it was subjected to least the amount of impact energy from that incident as possible.” In the years since the introduction of the Ghost Bandit, Simpson has expanded its motorcycle helmet offerings into a full line of products that have been developed specifically with riders in mind, and all of these helmets carry the ECE and DOT safety certifications.
Beckett also notes that helmet weight, aerodynamics, and modularity have become key factors in modern motorcycle helmet design. “Those have all become more specifically tailored to the application. Drop-down sun visors, color-changing shields, provisions for audio and communication systems – these sorts of things have come as a result of considering what motorcycle riders need instead of just forcing them to make do with an auto racing helmet that’s designed for a different use case.”
Proper Fitment Is Crucial
Beckett tells us that whether you’re a first-time motorcycle helmet buyer or an experienced rider looking to make an upgrade, there are a few features that should be on your radar.
“All-day comfort is hugely important here because riders typically wear their helmets for much longer periods of time than auto racers do, and you need a helmet that offers a level of adaptability that allows it to continue to function properly as lighting conditions change. The sun shield, for example, provides that glare reduction you need during the day, and you can just flip it up at night to bring more light in.”
He says that advanced materials also play important roles, too. “When it comes to the fabrics used inside the helmet, you want to look for something that can wick moisture away from your face, and also something that has an anti-microbial liner because motorcycle helmets are often worn for extended stints. You also want to keep an eye out for helmets that have aerodynamics which complement the riding position of the motorcycle you’re going to be riding. You’ll notice that helmets that are designed for the more upright riding position of a touring bike take a different approach to aero than those which are designed for the low-slung riding position of a sport bike, so that should be taken into consideration as well.”
But above all, a helmet must fit properly in order to do its job effectively. “The helmet should fit snuggly – you want good, constant pressure all around,” Beckett says. “That means your helmet will probably be a little bit tight initially, and that’s perfectly fine. For the first few hours or couple hundred miles that you’re wearing the helmet, it’s going to break in and start to conform to the shape of your head. Just make sure that it’s not creating pressure points that cause significant discomfort.”
Helmets need constant pressure against your head not only to keep the helmet correctly positioned during an incident, but also to eliminate the potential for a secondary internal impact within the helmet itself that a gap between your head and the internal lining might cause.
“That’s why it’s important to know your head shape,” he explains. “EPS liners are designed for different head shapes, which basically boil down to three types – round, oval, and intermediate oval, the latter of which is essentially a middle ground between the round and oval. The majority of our motorcycle helmets utilize the intermediate oval head shape design. Unless you have a really pronounced round or oval head shape, the intermediate oval is probably your best bet, and that’s why it has become sort of an industry standard.”
Read about the importance of helmet weight when choosing the right helmet here.
While going to a store and trying on helmets in-person is the best way to ensure that you’re getting a helmet that fits properly, there are a myriad of reasons why shopping online might be preferrable – or the only viable option. If the latter describes your situation, Beckett offers some tips to make the process less of a trial-and-error affair.
“After you’ve done a self-evaluation of your head shape, measure the circumference of your head using a tape measure one inch above your eyebrow. The tape should be as level as possible all the way around your head, and you should take the measurement with your hair placed where it would be while you’re riding with a helmet on – if you’ve got dreads or something like that, you need to have that hair positioned in the way that it would be when you’re putting on a helmet. The corresponding measurement in centimeters can then be equated to a specific size.”
Each Simpson helmet size has a two-centimeter range of variance – for example, a Large helmet size is designed for folks with a head circumference that ranges from 58 to 60 centimeters. And if your measurement puts you right on the border between two sizes, Beckett recommends choosing the smaller size of the two.
Shop Simpson Motorcycle helmets here.
“If you’re on the border between a Medium and a Large, for instance, you should try the Medium first. After the break-in period, the Medium will likely end up fitting perfectly, whereas the Large could end up being too big.”
Simpson also offers swappable cheek pad inserts that can further tailor the helmet’s fit to your specific needs. “We offer +5MM and -5MM cheek pad options,” he points out. “These effectively allow you to take a helmet of a certain size and make it fit like one size smaller or one size larger, even if that smaller or larger size is normally a different shell size. Switching to the -5MM cheek pads will provide a little more room, while the +5MM cheek pads will tighten up the fit a bit more.
Some people also like using the -5MM cheek pads because it allows them to use the smallest helmet possible, which keeps the weight of the helmet to a minimum. If you’re right on the border between not only two helmet sizes but also two helmet shell sizes – as is the situation with Simpson’s Large and Extra Large helmet sizes, for instance – you have to decide whether to go with the larger one and add thicker cheek pads to maintain a certain level of comfort, or to go with the smaller size and use thinner cheek pads and minimize the weight of the helmet. It ultimately comes down to personal preference.”
Beckett adds that the Simpson website offers a sizing chart to help customers determine how to get the best fitting motorcycle helmet possible.
“And if you have any other questions, just reach out to our customer service help center directly. These folks are experts in safety gear and can provide the answers that you need in order to make an informed decision.”






