In the United States, bicycle helmets must meet the Consumer Product Safety Commission standard, established in 1999. The standard tests a helmet's ability to reduce G-Force, measured in a drop test from a specified height. It also addresses retention, or strap strength. Honestly, the standard is fairly minimal, and does not address impacts from multiple angles or repeated impacts that are possible in a crash. Some helmet manufacturers also certify with SNELL, a non-profit that tests helmets. The SNELL standard B90A is almost identical to the CPSC standard. Manufacturers pay SNELL for testing and the right to display the SNELL label on their helmets.
SNELL not only does initial lab testing on the helmets for certification but also goes out and purchases helmets from retailers and tests them. CPSC does not monitor or test following initial certification. The primary advantage of a SNELL certified helmet to the consumer is that SNELL certification ensures that manufacturers have a high-quality control procedure in place that assures that helmets found in retail establishments continue to meet the initial certification standard over time.
In Europe, helmets must meet a different and arguably less stringent standard known as the CEN standard. Some manufacturers that sell helmets in the USA and Europe will offer two different versions, and you will notice that the CEN certified helmets are often lighter in weight, as they are able to manufacture the helmet using less EPS foam and still meet the standard. Read more about the electronic code of federal regulations.
Types of Road Bike Helmets
First off, it is important to note that this article is specifically discussing road bike helmets. If you are looking for a mountain bike helmet, then see our Mountain Bike Helmet Review. If you are looking for a helmet specifically for cross-country mountain bike racing, you may choose to use a road helmet; most of the pros do.
Fully Vented Traditional
This is the classic road helmet and probably the picture that pops up in your head if you were asked to describe a road helmet. These helmets prioritize low weight and good ventilation above all other factors. Good ventilation is understandably a priority for most riders. Choose one of these helmets if long rides in hot climates are frequent for you. If you are a racer and consider yourself a climbing specialist, then this is also probably the best helmet for you. We recommend the Giro Aeon or the Specialized Airnet.
Traditional helmets, such as the Bell Gage MIPS, prioritize ventilation and low weight over aerodynamic gains. They are good all-around helmets for training and racing. If long climbs in the heat of summer are your thing, then a traditional helmet is probably your best bet. Other helmets we tested that fall into this category are the Specialized Airnet MIPS and the Lazer Z-1 MIPS.
Aero Road Bike Helmets
These helmets prioritize aerodynamics above all other factors, and in general, tend to not be as well ventilated. Choose an aerodynamic helmet if you are a racer, and do a lot of crits or flat road races. Hard data on actual savings in terms of watts is hard to come by, but we have seen estimates in the area of 8 watts in the 25-30 mph speed range. Yes, that's correct - they are potentially faster, but the testing is done at speeds that pro riders race at. Expect the savings in watts to plummet as speed decreases.
We recommend that you only purchase an aero helmet if you already own another more ventilated model. The aero helmet should not be your only lid. Another group that seems to be fond of aero helmets are cyclocross racers. This has little to do with increased aerodynamic efficiency - cyclocross happens in the winter and it is often freezing cold. Aero helmets tend to be much warmer, and some of the sparsely ventilated models like the Giro Air Attack can help keep your head dry. We recommend the Bontrager Ballista, or if you want an integrated eye shield we recommend the Air Attack Shield.
Helmets with a pronounced aerodynamic shape have long been used for time trials. In recent years, helmets designed for road riding and racing with aerodynamic profiles have become quite popular with both amateurs and professionals. The Giro Air Attack kicked off the market segment and nearly every other helmet manufacturer has followed suit with an aero road-racing model. Minimal or not, vents are the norm, with a round or elongated smooth shell. Studies have shown aerodynamic drag to be one of the biggest factors affecting speed, and power output required to maintain a given speed. Professional cyclists go to great lengths to decrease drag, from wheels and bikes designed to create less drag to tight fitting kit. The shape and profile of a helmet also can increase or decrease drag.
How much speed can you get out of an aero helmet? Well, not much. Reductions in drag in the 2-3 watt range (at 30mph) are common manufacturer claims. For the average recreational cyclist this is inconsequential, but for a world tour level racer, the energy savings of a few watts over the course of a 7-hour stage of the Tour De France can add up. World-class sprinters like Mark Cavendish often win stages by millimeters over an opponent. So if all out speed is your goal, there is no disputing that an aero helmet can make a marginal difference. It is important to note though that the rider's body creates the most wind drag proportionally, and a good bike fit and an aero position on the bike can make huge gains in aerodynamic efficiency. The primary downside to aero helmets is poor ventilation, especially at low speeds. If long hot climbs are your thing, an aero helmet is probably not the right choice. If you live for the break away or are an aspiring sprinter, then an aero helmet may be right for you.
This is a newer category that aims to provide some of the benefits of aero helmets while still maintaining ventilation. This is likely the way you will see the helmet industry move in the coming years. We love the concept, and the Giro Synthe (winner of our Editors Choice) falls into this category. Buy a semi-aero helmet if you race and only want one helmet, or you just like the idea of saving a few watts and having a cool head. You really can't go wrong with this style of helmet. An added bonus is they do not look nearly as goofy as aero helmets.
Helmet manufacturers have realized the limiting nature of full aero helmets, and the result is semi aero helmets that offer better aerodynamics than a traditional helmet, but have enough ventilation to make them tolerable on a hot day. Examples include the Giro Synthe and the Kask Protone. We feel that the semi aero category, when executed appropriately, can offer the best of both worlds and is often the most pragmatic choice - especially for the amateur or master racer who does not want (or can not afford) to have more than one helmet. The Giro Synthe, winner of our Editors Choice Award, is a great example of how good a semi-aero helmet can be.
A more lengthy discussion of safety standards is available in our main review section, but in the essence of keeping your decision simple here is the bottom line: all of the helmets sold in the USA must meet the same CPSC standard, meaning that the $300 helmet is not safer than the $100 model. There is not a single manufacturer that will go on the record and claim that their product is safer than another brand's product. Some of this has to do with liability, and in part, it is a consequence of a helmet standard that has literally not changed in over 20 years.
Many brands have adopted MIPS liners, and use them in their products from the bottom of the range to the top. MIPS is a slip plane technology that claims to reduce the effects of rotational impact. Does it work? Maybe. MIPS, of course, claims it does, and the list of helmet companies on the bandwagon is a mile long. We say it is worth the additional cost and weight for the potential that it could work. Expect more research in the coming years on MIPS. So the bottom line is, choose a helmet that has a CPSC certification, which should not be hard since it is illegal to sell a helmet in the US without one.
Proper fit is not only important for safety, but also for comfort. The best way to see if a helmet fits you is to go and try on the model you are interested in. You can measure the circumference of your head to get in the ballpark, but helmets all fit a bit differently. Your head shape and how it interacts with the helmet you choose will have a big impact on fit and comfort. The only helmets we tested that seemed to offer a universally good fit were the Giro Synthe and the Giro Air Attack. Both helmets use the Roc Loc Air fit system, which is the only system that has a tensioning band that wraps all the way around the head. Basically, it conforms to your head shape, rather than your head being pushed into the EPS foam in the helmet. Bottom line: go and try them on before you buy.
How to Properly Wear
Helmets must be worn correctly in order to properly protect your head. This seems like an easy task, but we often see riders wearing them improperly. The most common mistake is to not properly tighten the chinstrap. Chinstraps should be decently snug and positioned at the point where your jaw transitions to your neck. It should not be so tight that you feel like you are choking, but tight enough to keep it on should you dismount your bike going 40 mph.
The second most common mistake is to wear a cycling helmet tilted rearwards, exposing the forehead. This happens with ski and snowboard helmets too, and seasoned shredders describe the exposed forehead between the goggles and the helmet as the "dork gap" or "gaper gap". Avoiding dork gap is easy. All you need to do is wear the helmet level. The front of a cycling helmet should sit just above your eyebrows.
The difference between the high-end model and a low-end model is generally a matter of weight, materials, and features. Lower-end helmets tend to not have the best quality padding, and they often have thicker, less supple tubular webbing rather than the thin single layer stuff found on high-end helmets. All things being equal, the cheaper helmet will generally be heavier than the higher-end helmet. This applies when comparing apples to apples, meaning a two traditional MIPS-equipped helmets, one costing $100 and the other $300.
Budget models (for the most part) forego features like rubber sunglass grippers in the vents. You can buy a fully functional, safe helmet for $100, the Bell Overdrive MIPS being a great example. If you are willing to spend a bit more, say $170, you can get the Specialized Airnet, or an aero helmet like the Bontrager Ballista. Top of the line helmets will run you between $260 and $300, with the Giro Synthe being a great example at $270. There is a helmet in almost everyone's price range, so there is no excuse not to wear one.
Can I use a Road Bike Helmet for Mountain Biking?
Yes! But should you? Well, that depends. If you watch World Cup-level cross-country mountain bike racing, you will notice that almost all of the racers are using road biking helmets. The reason is weight. Road bike helmets tend to be lighter than mountain bike specific helmets. Legally, half shell mountain bike helmets are subject to the same CPSC safety standards as road helmets. So a mountain bike specific helmet does not necessarily provide any greater impact protection than a road helmet.
You will notice that most helmets marketed towards mountain bikers have greater coverage, particularly at the back of the head, than most road helmets. Mountain bike helmets, for the most part, also come with a visor. Those two design features account for most of the weight increase. So the bottom line is you get a bit more coverage with mountain bike helmets, but they are not required by law to meet a more stringent standard than a road helmet. For XC racing we say go for the road helmet, but for aggressive trail riding, we prefer a mountain bike specific helmet.
Full Face Helmets
Full-face helmets for downhill mountain biking use are required to meet a different safety standard, ASTM-F1952. The ASTM standard is more rigorous than CPSC, and includes tests on the chin bar of the helmet. Some downhill riders also choose to use DOT rated helmets, as they feel they provide a better level of protection.
MIPS is a safety feature added to many cycling helmets and has gained a huge foothold in the cycling helmet industry. Most manufacturers offer a helmet with MIPS, and many offer MIPS as an option in nearly every helmet they make. MIPS stands for Multidirectional Impact Protection System. Essentially, MIPS is a thin plastic liner that sits against the head - low friction material is attached to the inside of the EPS foam in the helmet, and rubber anchors hold the MIPS shell in place. MIPS technology is designed to allow the helmet to move independent of the MIPS liner in order to redirect energy from a crash and reduce the likely hood of brain injury. Does it work? If you read the R&D papers that MIPS displays on their website, then yes. It should be noted however that there is controversy over the research showing the efficacy of MIPS. Not all players in the helmet world are in agreement.
Much of the controversy has to do with the way MIPS is designed to work, and how it actually works in the real world. For MIPS to work, the contact with the head must be tight, and the MIPS liner should only contact the EPS shell where the low friction material is attached. The argument of MIPS naysayers is that helmets are not worn tightly enough by most consumers for MIPS to work, nor is there any standard on how tight a MIPS helmet needs to be to work. If you look closely at many MIPS helmets, you will see that the MIPS liner clearly contacts the EPS shell in places that are not lined with the low friction material, which in theory would limit the effectiveness of the product. The bottom line is that the scientific research regarding MIPS is ongoing, and the effectiveness of the product is dependent on proper fit and good design collaboration between MIPS and the helmet manufacturer.
Despite the lack of solid evidence on the effectiveness of MIPS, we recommend you choose a helmet with MIPS if it is offered in the model you want. The weight penalty of a MIPS liner is between 20-30g depending on the model, with an average price increase of $20-$30. We feel that these are acceptable price and weight increases for the potential to decrease the severity or occurrence of a head injury. We would not necessarily recommend you replace your existing helmet just to get a MIPS version, but if you are in the market for a replacement, choosing a MIPS helmet is not a bad idea.
For more information on helmet safety, we recommend this non-profit for independent, non-industry funded information.