Bicycle Helmet Safety Institute

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Our Ideas on the Ideal Helmet

Summary: Eleven Principles for the Best Helmet

1. A helmet should manage as much energy as possible in a very hard crash, keeping g levels in lab testing as low as possible, but certainly below 200 g for a two meter drop. In a lesser crash it should keep g's below 75. It should be able to handle multiple impacts.

2. A helmet should have a strong strap that keeps it on your head after the first impact (car) for the second impact (street). Child and toddler helmets should also have a buckle that holds firm in a crash but releases after 5 seconds of steady pull to avoid strangling a child who climbs trees or uses playground equipment with their helmet still on and gets caught.

3. A helmet should be easy to adjust properly or be self-adjusting, and designed to encourage a good fit without excessive fiddling. Once adjusted, the adjustments should stay put.

4. A helmet should be comfortable to wear: cool, light, unobtrusive to the user and fashionable in appearance. The quality of the materials should be apparent.

5. A helmet should be as smooth and round as possible on the outside to prevent snagging in a crash. It should not have an "aero" tail that can shove it sideways in a crash and leave the rider's head unprotected. (Specialized time trial helmets are an exception.)

6. A helmet should provide for mounting of a mirror and a visor with breakaway mounts. If it has a visor, it must be shatterproof.

7. A helmet should be highly visible to motorists and others both night and day.

8. A helmet should be durable, easily cleaned, and should not scuff or dent in normal use.

9. A helmet should come with clear, understandable instructions for fitting and use.

10. A helmet should be cheap and readily available in retail stores, including local bicycle shops.

11. A helmet should be readily recyclable when its useful life is over.

So Who Makes One Like That?

Nobody, that's who. Let's look at current production principle by principle, then we will speculate on why you can't find our ideal.

1. Crash Energy Management

In lab tests, helmets are dropped with headforms inside and are expected to keep the g forces registered by instruments inside the headform below 300 g. (We have a page on "What is a g" if you are not familiar with the term.)Most helmets now on the market are designed to that 300 g standard, with the manufacturer striving to get below 250 g to make sure they can always pass even in the event of minor quality control glitches. That's just not state of the art. But without more current and more frequent test reports we are never going to know which helmets might be better, and there is no incentive for manufacturers to produce a super-protective helmet. In addition, there are many in the helmet field who believe that since most heads can take 300 g without permanent damage, there is no point in making a helmet to provide a softer landing than that. We, and a growing number of experts in the injury prevention field, think that lesser injuries should not be ignored. In our case we base that on reporting from the medical community that damage from brain trauma is often not recognized by clinical examinations. If the patients walk out of the hospital in apparent possession of their faculties they are "cured," for all the clinician can tell. In addition, some researchers believe that older riders are much more easily injured in a crash because their brains and the connecting nerves and blood vessels have become less flexible and more brittle with age, just as the rest of the body does. But if you are a senior citizen or you accept the argument that a softer landing is better, there is no lab data to help you make a choice.

Most riders are used to the idea that almost all of today's helmet should be discarded after a crash. But a surprising number of riders will continue using the helmet anyway. An ideal helmet would be multi-impact.

Medical research shows that current helmets work well, but we think there is room for improvement, particularly in providing a "softer landing." We have a page up on helmet foam that provides more detail on possible use of new materials. And there must be many other possible solutions for a better helmet that nobody has thought of or marketed yet. For example, helmets with a "slip plane" of layers that slide on impact are rumored to be effective in reducing both rotational and translational impact. Cars may some day have exterior airbags to protect pedestrians. Perhaps that technology could be translated into exterior devices on a helmet that would inflate when the rider approached a hard surface at high speed. Somehow we have to provide a greater effective thickness for the helmet's protection, to give the head longer to slow down. Perhaps some day that will be a force field, produced by a wafer held under your tongue. In the meantime, there is no reason to keep thinking inside the shell of the helmet when we look for solutions. Our page on patents has more on cutting edge ideas.

Standards in the US have evolved over more than two decades since the original ANSI Z90.4-1984 standard was adopted in 1984. ANSI let its standard lapse rather than update it, and the ASTM bicycle helmet standard took its place for some years. Now all helmets manufactured for the US market after 1999 must by law meet the Consumer Product Safety Commission's standard (CPSC). So you should be looking for a helmet with a sticker inside that says it meets the CPSC standard. There are also the Snell Foundation's bicycle helmet standards. Some manufacturers are still using Snell's older B-90 standard (introduced in 1990) which is comparable to CPSC. But Snell's newer B-95 standard is the most stringent standard in the market -- more difficult to meet than the ASTM or CPSC standards -- and ensures that the helmet has been certified by the independent Snell Foundation labs. We would prefer a Snell B-95 helmet, but we would not worry much about the differences between that and a CPSC helmet. And some day we would like to see the CPSC standard improved to require more coverage and a softer landing.

2. Strong Strap that Still Releases a Child

A helmet must stay on the rider's head after the first hit by a car to protect against the typical second hit on the road surface. So it requires a strong strap. Long experience with bicycle and motorcycle helmets shows that riders are not "hung" by their helmets during crashes. But children sometimes keep their helmet on while playing on playgrounds, or climbing trees, and we are aware of some incidents where the helmet strangled a child momentarily until rescued or for longer periods sometimes resulting in death. Here is a page with details on this problem. Rather than chide the parents for not supervising the child at play closely enough, or trying to teach 3-year-olds to take off the helmet when they arrive at a playground or climb a tree, helmet manufacturers should develop a slow-release device that has strength in momentary crashes but would release after several seconds of steady pressure.

3. Adjustment and fit

Since today's helmets are working well and the standards issue is much less important than in years past, the big frontiers in helmet promotion are encouraging people to use them and encouraging users to pay attention to fit. We are also encouraging manufacturers to develop better fit systems. To stay on your head in a bad crash the helmet has to be securely strapped on, not just sitting on your head. It must be level on your head and not tilted back, or big chunks of forehead can be left completely unprotected. (Seeing the rider's bangs in the front is a red flag and demands immediate action to adjust!) So you want a helmet that fits well. Today's helmets generally can be made to fit, but some of them require ten or fifteen minutes of fiddling with straps to achieve that. Generally speaking, the ones with rear stabilizers are the easiest to fit, and the models with easily locked adjusters make it easier to achieve good adjustment by providing cams or other flip-type clips. In the 2002 season helmets appeared with the old 1980's Bailen-style adjustable ring inside, sold as a "new" concept: one-size-fits-all. Since then many manufacturers have converted some or all of their helmets to ring fit systems. We have a page up on the "one size fits all" concept. Some of them require the ring so tight for real stability that they feel binding after a few minutes, and loosening the band gives a sloppy fit. The headband used will also interfere with anyone using a separate sweatband or earband much more than a model with the adjustability of traditional fit pads. And most helmets still have a problem with "strap creep" as the straps loosen during repeated use. Users should not have to resort to needle and thread to keep the helmet in adjustment!

Despite some advances, there are still combinations of helmet and individual head that just don't work. You need to try a helmet on before you buy it, and verify that it can in fact be fitted to your individual head bumps. As always, your own head is still the only true standard for fit. Time invested in doing that pays off in years of comfortable, safe riding.

A particular fit problem arises with current helmets if the rider has thicker hair. Braided hair, particularly with beads incorporated, can raise the helmet above the head enough to affect coverage. Aside from a few helmets with pony tail ports, there is nothing being offered on the market yet that accommodates this phenomenon, even though braided hair styles have been around for centuries.

Since head shapes are different, and most current helmets fit better on a specific head shape, is it too much to ask for a system of characterizing head shapes? A helmet box should say something like "this helmet fits best on elongated heads." Or perhaps "this helmet can be easily adjusted to fit rounder heads."

When asked what we want in a fitting system, here is our response: What we are looking for is essentially the fiddle-free fit system. When you put it on, it centers the helmet correctly, places the V in the straps (if there is a vee, if in fact there are straps) where it belongs, sets or indicates the proper tension and holds securely as soon as the buckle is snapped. After one or twenty rides it is still positioning the helmet just as well, having either not stretched or crept from jiggling, sweat, fit pad compression, sun tan lotion and tugs, or having made up for any strap creep by itself. Ideally it would be fastenable and unfastenable with one hand and a minimum of finger strength and dexterity. It would not pinch when fastened, or chafe while riding. It should be comfy, and not add a lot to the cost of the helmet. It should be made with readily available materials that can be reliably sourced in very uniform batches that do not require constant recalibration and other heroic quality control measures. The goal is a one inch maximum travel in any direction when the helmet is violently twisted and moved on the head. And of course it would hold in a jerk but release in a slow steady pull to let a child on a playground down from the monkey bars where his head is caught.

In 2009 Bell introduced a new fit system called True Fit. It comes closer to our ideal than most others, requiring only that the chin strap be adjusted carefully. The result on most heads is an adequate, if not entirely optimal, fit. The buckle can creep over time, but the junctions of the straps on the side are permanently sewn.

4. Comfort and Style

There is not much to complain about in today's helmets. Even the cheapest ones are reasonably comfortable, and they all weigh in at about 10 to 12 ounces. Differences in weight are usually less than the weight of your pocket change or key ring, so you don't need to search for the very lightest one unless that's one of your hobbies. There are more differences in ventilation, however, and only the periodic Consumer Reports articles cover that, so you will need to ask riders who have worn that helmet in very hot weather for a comparison. Shop people are usually knowledgeable on that subject, although somehow their recommendations generally seem to involve the most expensive helmet in the shop.

If you are on your own, the general rule established by a British university study some years back is that despite marketing claims for ramming air through and sucking air out, the basic principle prevails that the larger the front vents, the cooler the helmet. There are now many "hyper-ventilated" helmets on the market following in the footsteps of the mid-1990's Giro Helios (more vent than helmet), but most riders do not really need extreme vents except for style.

Cooling can be enhanced on almost any helmet by careful placement of fitting pads to permit air channels around the sides. Many riders find that they need a sweat band to keep their eyes clear, and that most helmets do not have adequate sweat control. That forces you to use a separate cloth sweatband, which wraps entirely around the head and is much hotter. The advantage is that in winter you just swap the sweatband for an ear band without changing the fit. For more on ventilation, check out our page on helmet cooling.

Style is as individual a choice as it is with any piece of clothing. Just steer clear of the most extreme gimmicks. Aero helmets don't save any appreciable drag until you get to competitive cycling speeds--over 20 MPH. And that aero tail sticking out the back might snag in a crash. But the style appeals, so if that's what inspires you, buy it.

Some people want the most expensive of everything, and you will find many manufacturers ready to smile and relieve you of that burdensome cash. Again, the local shop can tell you what the "hot" helmet is this year.

5. Outer Shell

In a crash you want an interface with the road that is smooth, hard, round and slick. That keeps your head from snagging, which can add to the severity of the impact and may even jerk your neck. The elongated "aero" style has a tail on the rear than could shove the helmet aside when you hit, leaving your head unprotected. Professor Hugh Hurt raised this question again, based on both testing problems and field reports of injury from helmets being pushed aside.

There are very few hard shell helmets like the 1970's models, primarily because they were so heavy and expensive to manufacture. Only one company makes them today in true ventilated bicycle styles, Hopus Technologies, and their updated models show what you can still do with ABS hard shells. The thin shells on today's market are nearly as good in sliding resistance, and some of them are evolving into slightly harder shells now as the manufacturers try to open up more vent area and rely more on the shell for impact strength. Vents are necessary, but must be smoothly faired into the helmet shell. We advise consumers to avoid any helmet with unnecessary fashion ridges on the outside, or protruding snaps for visors, or any other feature that could cause the shell to snag. This is an easy item for a consumer to assess, as long as you keep in mind that you want your head to slide on impact. We hope to amend the ASTM standard some day to add a requirement to measure sliding resistance of the shell. We have put up the lab study that established the value of a round, smooth, slick outer surface if you want to see the scientific data.

6. Mirrors and Visors

We use mirrors and believe that any vehicle on the roads needs one. The eyeglass-mounted ones can present a gouging hazard in a crash, so we prefer a helmet mount version with a flip-off mount using hook-and-loop. Most helmet mirrors are very small, about 1 inch square, but they work surprisingly well.

Some users are bothered by glare or when the sun is low on the horizon and find that a visor can work wonders for them. (If you use contact lenses, try a visor.) But we avoid visors as just another impediment to smooth sliding in a crash. And they are not tested under any current US bike helmet standard for such hazards as shattering in an impact, which can mean a nasty facial or eye injury. They should probably be reserved for those times when you are riding into a low sun or are riding slowly enough in rain for them to keep your eyes or glasses clear. In addition to mirrors and visors, some commuters prefer helmet-mounted headlights or rear blinkers.

At very least, a visor, mirror, light or any other external accessory should be on a breakaway mount such as hook-and-loop tape. Many helmet manufacturers now provide visors, and most of them are properly equipped with breakaway mounts. But few have a provision for a mirror mount, or for mounting lights, so you are on your own to add those. Keep in mind that you don't want anything up there than can snag. Do not attach a light or anything else to your helmet with screws! Even the hook-and-loop tape can have a lot of breakaway resistance, and leaves a patch of rough tape on the surface of the helmet after the accessory breaks away. The trade-off is up to you. One mirror alternative is the tiny stick-on mirror that sticks to the inside surface of your riding glasses. These may work for some riders, but if you have big hair on the sides they are out.

7. Conspicuity

What's that word? Making a helmet conspicuous can have a big effect on safety. If a driver sees you they will try to avoid hitting you. If they don't hit you, you will not need your helmet's impact protection. But many of today's helmets are fashionably dull and dark, and just do not show up on the driver's radar. Once there were neon helmets, but they went out of fashion. Now the best you can do most of the time is a white helmet, which is actually the optimum color after dark, and not bad at all in daylight.

Few manufacturers put reflective tape on helmets now, so you have to add your own. Beware of the silver tape you see on some helmets. It mimics reflective tape, but in many cases it is not, saving the manufacturer about ten cents. In night-time tests we helped to organize for the Consumer Product Safety Commission we tried to demonstrate the effectiveness of various types and amounts of reflective tape on a helmet. We thought the riders were more conspicuous, but that could not be confirmed in CPSC's objective testing. Using state-of-the-art tape, as little as a band around the helmet about three-eighths of an inch wide was effective. Most tape on the market is not state-of-the-art, however, and needs a wider band. (Testing reflectivity requires a flashlight held at the side of the head close to your eye.) We hope that CPSC will some day add a reflective tape requirement to their standard. Meantime, you have to do it yourself. One Swedish manufacturer began making helmets with reflective shells in 2002, and a few others have followed.

Active lights on helmets are far superior to reflective materials. There are some on the market with good breakaway mounts to avoid snagging your head in a fall, and eventually we may see thin film technology or LED's used to bring surface lighting to helmets.

8. Durability

A study of motorcycle helmets showed that the foam can get indented inside under use, but it does not affect protective capacity very much. We hope that applies to scuffed-up bike helmets as well, although we have not seen studies on that question, and bike helmets are thinner than motorcycle helmets. Most durability issues center on the buckle and strap. There have been no buckle scandals in the past ten years, but plastic breaks, and buckles break. When any part of a buckle breaks off you must replace it! That advice sounds a little simplistic to us, since many riders are not even aware when one prong of a buckle has broken off. Until the mid-80's you could still buy a helmet with D-rings, which we believe are still the most reliable, strongest and most durable buckles ever fitted to a bike helmet. They also permit adjustment every time you put the helmet on. They just aren't stylish, and some people have trouble threading the strap through them, so you only find them on motorcycle helmets now.

9. User Instructions

Instruction manuals have become more elaborate as helmet lawsuits have increased. In some cases the needs are simple, like a label that tells you which end of the helmet is the front. In other cases the need for lots of instructions is due to fussy and difficult-to-adjust fit systems, as we noted above. Since few people read the instructions, the ideal helmet should be usable instinctively with minimal prompting from the manual.

10. Availability and Price

Helmets are available in discount department stores, toy stores and other retail stores. The nicest ones are usually still sold at your local bike shop, but the discount lines are equally protective. Since 1999 any bike helmet, including those sold in discount stores, must meet the CPSC standard by law, which ensures a good level of protection. And prices are right. It's a buyer's market out there, and helmets are cheap now.

What would our ideal helmet cost? Probably no more than the ones in the stores now. We have a page detailing how the costs add up. And 2009 research shows that the impact performance of expensive and cheap helmets is virtually identical. But we do not rule out the possibility that a new technological advance could be costly.

11. Recycling

Consumers are frustrated that a helmet that has served its useful life can not be readily recycled. Our page on recycling helmets notes that there are a few specialized foam recovery companies that can handle used EPS foam, but it is questionable whether or not it's worth transporting the helmet to the recycler. The difficulty of recycling helmets combines with their single crash characteristic to result in millions of helmets going off to landfills each year. Helmet manufactures should be looking at the life cycle of their products and developing a solution for recycling.

Why Not?

Where are the ideal helmets? For reasons that have to do with technology and marketing you will not see one this year. So we are not looking for the ideal helmet anytime soon. But putting forth the principles helps to clarify thinking about the current crop of helmets and what could be done to make them better. And we do sometimes see modest progress in the right direction.