How to Choose Your Next Bike Helmet
Update 4/14/22 - Added info about Lazer KinetiCore as an alternative to MIPS helmets.
Whether you’re heading out for a long ride or just tooling around town, if you are going to ride a bicycle, it is critical to wear a bike helmet that fits your head properly.
Each helmet sold in the United States must meet the same minimum standard for impact protection. That basic standard has hardly changed the years while helmet technology, materials, and safety features continue to evolve. As such, when shopping there are a few other factors to consider:
A helmet will only protect you as well as it fits your head. Poor sizing - even if the helmet is one-size-fits-all - can compromise overall protection.
You're going to want a helmet that matches how you like to ride your bike. A lightweight road bike helmet can be ridden on the trails, and an airy mountain bike trail can be ridden on the road, but finding a helmet that matches your needs matters! There are three basic types of helmets:
- A road bike helmet is designed to be lightweight, highly ventilated, and is often designed with aerodynamics in mind at the expense of some coverage. SHOP ROAD BIKE HELMETS
- A mountain bike helmet trades a bit of ventilation and weight for additional rear head coverage. These are available in a half shell or full-face style. SHOP MOUNTAIN BIKE HELMETS
- A recreational bike helmet tends to blend road bike and mountain bike helmets, while being a bit simpler overall in construction and features. SHOP RECREATIONAL BIKE HELMETS
Think about the type of design you might want. Of course, the more features the helmet has, the higher the price of the helmet will be.
How Helmets Are Designed to Work
Okay, now to the nitty gritty! A main role of a helmet isn't to make you feel dorky. Nor is it to make you faster (which the best aero helmets do!). Really, the main role of a helmet is to prevent head injury in the event of a crash. It does so by absorbing the energy of impact against the ground and redistributing that force through the rest of the helmet.
Helmets are traditionally made of foam to absorb impact force, a retention system, and a plastic outer. Helmet foam is not made equally, and as you spend more money it will become lighter, stronger, and better optimized for impact protection. The retention system should be comfortable while preventing the helmet from coming off in an accident.
What is MIPS?
Sure, every helmet sold in the U.S. is designed to meet the same minimum amount of safety. However, some helmets employ different technologies that factor into a helmet's overall safety.
The most common technology helmets have adopted recently is MIPS (Multi-directional Impact Protection System). MIPS is made of a thin layer inside of the helmet that is often called a slip plane. It effectively turns the helmet into two parts, as the MIPS liner can move independently of the helmet with about 10mm of rotational movement. In turn, this allows the structural foam part of the helmet to rotate independently from the head upon impact, which reduces rotational motion of the head itself and by extension the brain.
In short, MIPS means that rather than your head moving upon impact, the helmet does. Less force to your head means less force to your brain.
Does MIPS - or the other equivalents out there - make a helmet safer? Hard to say. MIPS claims that a MIPS-equipped helmet is at least 10 percent better at handling rotational impact than the same MIPS-free helmet. Some brands like Giro claim the improvement is closer to 20 to 60 percent over a standard helmet.
The most prominent alternative to MIPS is called Spherical, employed by Giro and Bell in helmets like the Helios (review) and Manifest (review). Spherical takes MIPS to the next logical level, taking the plastic slip plane that was an additional element to the helmet and making it an integral part of the helmet. The technology was developed in partnership with MIPS, and is pulled from their alpine skiing helmets, where speed and impact forces are higher than on a bike. What riders will notice, particularly those with lots of hair, that their hair is much less likely to get stuck in a Spherical helmet than a MIPS helmet. They are also likely to notice the improved fit and ventilation that Spherical promises.
Kineticore is a relatively new addition to the world of rotational helmet impact protection technology. While most of these system are technologies added on top of the standard foam of a helmet, Lazer KinetiCore is built directly into the helmet's foam. How it works is that Lazer molded small blocks and channels into the foam that are designed to absorb or redirect impacts. The best way to think of this is like a built-in crumple zone, where specific bits of foam will more easily compress to absorb the energy of a fall and prevent it from reaching the rider's head.
How to Find a Bike Helmet That Fits
Technology makes a difference in choosing a helmet, but nothing makes a bigger difference in choosing a bike helmet than fit. A poor-fitting helmet can compromise how effective a helmet protects your head in a crash!
While some helmets are available in a one-size-fits-most, most helmets will typically come in a 'small', 'medium', or a 'large'. Not all mediums fit the same however! Some helmet brands tend to fit an average head well, like a Giro, Smith, or Lazer. Other brands like Kask, tend fit more oval or narrower heads well.
The best way to get an idea of what helmet fits you best is to go to a local bike shop, where a staff member will walk you through properly sizing a helmet. But it can be helpful to do your homework ahead of time and figure out your size. To do so, grab a tape measure and measure the circumference of the widest part of your head, which is usually about two fingers above your eyebrow.
Once you've found a helmet, snug down the tightening mechanism - often a knob at the back or top of the helmet. It is important to ensure that you don't rely purely on the tightening mechanism to make a helmet fit properly, and that the mold itself should fit the head nicely.
Next, buckle and tighten the chin strap. When buckled, you shouldn't be able to lift the strap over your chin. The helmet should feel comfortable, and the straps should fall into an even 'V' shape on each side. If they don't, most helmets straps are adjustable to accommodate different head shapes.
Our rule of thumb is that if you're between sizes and fit either comfortably, size down. A properly-fitting helmet should be snug without creating pressure points on your head. The helmet should sit roughly level on the head, usually about two fingers above the eyebrow (or roughly one inch). Helmets with MIPS might shift around a little more than a non-MIPS helmet, but it shouldn't shift around more than an inch or so. If it does, readjust the helmet.
How to Choose a Kids' Helmet
It is important to note that all the fit guidelines found above also work when you want to buy a kids' bike helmet. However, kids have a few other needs when looking at a helmet, namely a need to have a helmet that might fit them as they grow. To note, an overly-large bike helmet does not provide proper protection; rather many kids bike helmets use adjustable retention systems or additional pad options that can accommodate a kids head as they continue to grow.
Kids helmets for the youngest children tend to be a one size fits all proposition, and normally fit a head around 45cm to 54cm. They will come in myriad designs to fit your kid's preferences, but most of them tend to follow more of a mountain bike helmet design, with more coverage and fewer vents. Once they grow out of a 54cm or so helmet, a size small adult helmet is often the next logical step.
Differences Between Helmets
All bike helmets have some sort of retention system for the back of the helmet. This tightens a brace around your head to make the helmet fit more snug. Some helmets extend that retention system to the entire head, wrapping from front to back.
Some helmets - generally road bike helmets - will emphasize ventilation, which matters on a hot day regardless of if you're going 25 miles an hour or trudging up the trail at 2.5 miles an hour. The more vents on a helmet, usually the lighter it is as well.
Other helmets - generally mountain bike or recreational helmets - will include a visor of some sort. Some visors extend farther out than others, but all of them seek to do three main things: protect your eyes from the sun, kicked up dirt, and from stray, low-hanging branches.
Some mountain bike helmets have a wraparound chin bar to provide full-face protection. If you appreciate the protection but don't always need it, there are a few helmets - like the Bell Super Air R - that have removable chin bars.
Those with long hair must consider how well a helmet will work with your hair. Some feature retention that goes down particularly low - like Kask - to fit a ponytail into. Other helmets - like Lazer - feature a retention system that is molded to fit around a pony tail without compromising safety. Of course, the best way to find what works for your head and hair is to try them on.
How Often Should I Replace My Bike Helmet?
Unfortunately, your favorite helmet won't last forever. Right after a crash is a perfect time to replace a helmet. The helmet is designed to absorb impact once, and while it may protect your head in the future, it will not do so with the same effectiveness.
What if you've lovingly cared for your helmet for years and want to keep using it? The foam that a helmet is made of will slowly weaken with time, and that degradation will be accelerated with exposure to the sun, heat, and elements. Most helmet manufacturers recommend replacing a helmet every three to five years as that will ensure the helmet functions as designed in the rare occasion that you might need it.
The right bicycle helmet is often an afterthought when going out on a ride, taking a back seat to flashier things like a bike or computer. A helmet, however, is something you'll use every time you head out on the bike, so having something that is comfortable and fits your needs should be paramount.
Regardless of what helmet you choose, each is rigorously tested to protect your head against high-impact, high-velocity crashes. Finding a helmet that is comfortable and looks good will mean you'll wear it more, and wearing it more means more protection.
Have any questions or want us to help you find your next helmet? Come visit us or send us an email any time to firstname.lastname@example.org.