Protecting Your Head
In Crash Padding - part one we focused on everything below your neck. With this piece we'll discuss your brain, ears and eyes.
If you bash into a left-turning car, or lose traction drifting through a puddle of diesel oil, you’ll go sliding, and there’s a good chance you will bang your head into something. Whether you prefer to wear a helmet or not, we have a pretty good idea of what helmets can and can’t do in such situations, plus some advice on when to retire your old helmet and buy a new one.
You may have seen that videotape of two ripe cantaloupes being dropped onto the pavement—one “bare headed”, and one strapped inside a helmet. If you haven’t seen it, you can use your imagination about the results. And you’re right—the unhelmeted cantaloupe smashed wide open, spilling its brain-like guts out onto the tarmac.
Such macabre demonstrations certainly get my attention, but in truth that one was more enlightening about cantaloupes than human heads. You see, the big risk of smacking your head into something isn’t cracking the skull open, it’s injuring what’s inside your skull: your brain.
Bruising The Brain
Banging your brain around is a Big Deal because the brain is a special organ that doesn’t heal itself like other parts of the body. If you cut your finger, the cut will heal itself, perhaps leaving only a faint scar after a couple of weeks. But brain tissue just doesn’t heal that easily. A little bruise on the brain is very likely to be a serious, permanent injury. And even if you manage to avoid traumatic brain injury during the accident, it is not uncommon for a bruised spot on the brain to start firing random impulses two or three years down the road. The doctors call it “epilepsy”, and you don’t want it.
What a helmet can do is spread out and slow down the impact forces of a sharp blow to the head, which helps prevent the brain from banging around as violently inside your skull. The outer helmet shell is important, since it spreads the blow over a wider area, holds the foam liner in place, supports eye protection, and provides a way to attach the helmet to the head. We tend to think of a helmet as that colorful hard plastic shell, but the most important part is the crushable foam liner inside. The foam liner absorbs energy as it crushes, helping decelerate the skull and therefore reduce shocks to the brain. The crushing may seem to be instantaneous, but it really occurs over a few milliseconds, just enough time to soak up a lot of energy.
You can get some idea of how a helmet works by trying to smash two or three nestled foam coffee cups with your fist. The foam may break into bits, but it absorbs a lot of energy very quickly.
Hitting The Ground
The big question for a motorcyclist is: what sort of impact forces are we looking at in a typical motorcycle accident? And what sort of protection can we realistically expect from a good helmet? Objects in motion can generate some big g forces, even if just for a millisecond. What sort of impact speeds will generate high enough g forces to cause brain damage?
David Thom is Vice President of the Head Protection Research Laboratory in Paramount, California, and has spent many years studying helmets and motorcycle accidents. Thom suggests that 9 out of 10 head impacts are blows against the road surface, and that the impact forces generated by simply falling off your bike and hitting your head on the ground are sufficient to cause irreversible brain injury. Fortunately for motorcyclists, we seldom smash directly into fixed objects such as power poles or brick walls, but it’s relatively common for a rider in a collision to slam into the car, tumble over the top, slide down the pavement, and bounce off a curb. You can imagine that such violence creates lots of opportunities for glancing blows to the head.
Different Strokes for Different Folks
Different styles of helmets provide more or less brain protection, even though each may meet the federal DOT or private SNELL Foundation standards. The style of helmet you prefer tends to be determined by your habits and experiences. If you’ve been riding since the days of Black Shadows, Square Fours, Hydra Glides and Chiefs, you may think of a helmet as a claustrophobic nuisance, and a shorty helmet as barely tolerable. But if your riding experience started with machines such as Interceptors, CBR’s, GXR’s, or FZR’s, you may feel naked if you aren’t wearing a full-face helmet.
It might be helpful for you to know the typical impact points where helmets have smacked into things. The image above shows the distribution of impact points, based on accident reports from Germany. Keep these numbers in mind when you are deciding on what style of helmet to buy. In a nutshell, the more facial coverage, the more protection.
Helmet manufacturers constantly search for shell materials which are the best compromise between manufacturing practicality, rigidity, weight, energy absorption, and cost. We want the helmet shell to be rigid in order to spread the impact loads without deforming too much. It might seem that a very strong, light helmet shell would be ideal, but we really want a shell that isn’t too strong, so it will absorb energy by destroying itself. Fiberglass composites have turned out to be an excellent shell material, because fiberglass is not only lightweight and reasonably rigid, but also has the unique characteristic of absorbing shock by partially tearing apart, or “delaminating” during impact
There are two primary testing standards for helmets in the United States: Federal Department Of Transportation (DOT), and Snell Memorial Foundation (SNELL). Both standards test for shell penetration, impact reduction, retention, and peripheral vision, but the testing procedures and limits are slightly different.
Years ago, there was an ANSI Z90 standard, which was approximately equivalent to the SNELL ’68, and the forerunner of the DOT rating. The DOT standard was established in 1974 by the U. S. federal government via the “Motor Vehicle Safety Act”, and currently applies to all 50 states. All motorcycle helmets sold for public use must meet the DOT standard, whether or not the state has a mandatory helmet law.
The SNELL standard was established by the Snell Memorial Foundation prior to the development of the ANSI or DOT standards, but it is still in use, and is updated about every five years as technology changes. SNELL was developed for motor vehicle competition, where higher impact speeds and multiple strikes may occur. The latest SNELL standard also tests for impacts against race car roll bars. The SNELL standard typically requires a higher impact energy reduction than DOT.
A helmet may meet both DOT and SNELL ratings, but a SNELL rating doesn’t necessarily mean greater protection against brain injury, for a motorcyclist. Most experts suggest that the standard should be subordinate to other considerations such as proper fit, comfort, and crushable foam in the chin bar of full helmets. High-end helmets may not provide any better impact protection than a low cost helmet, but offer useful features such as lighter weight, more practical faceshield operation, customized padding, better airflow control, better rain resistance, or lower noise levels. Arai’s Bruce Porter believes that the price of a helmet is a pretty good indication of its quality and usefulness.
Fit To Be Strapped
Whatever the standard or helmet style, it is most important for a helmet to fit the rider’s head snugly, and for the helmet to not come off in a crash. Different brands of helmets have different internal shapes, and different riders have different head shapes.
Since different helmet manufacturers have a different idea of the “perfect” head shape, the best suggestion is to try and buy at your local dealer, where you can compare different brands and sizes, and determine which brand or style fits your head best. Since a helmet tends to loosen with use, a new helmet should fit snugly enough that you can shake your head vigorously without having the helmet wiggle around. If you think a new helmet is a little too snug, it’s probably about right. Within a few days of use it will loosen up and be more comfortable.
Be aware that the DOT “retention” tests generally test only for chin strap and fastener strength. We’re gradually learning that strap configuration is just as important as strength. The potential problem is that the helmet might roll off forward over the riders forehead during an accident. The SNELL 95 standard is currently the only American standard that includes the important helmet “roll-off” testing, although the DOT is considering adding a rolloff test.
A “Y” shaped strap configuration, or careful placement of a single strap attachment point helps prevent rolloff. You can easily test a helmet yourself. Secure the strap, then reach over the top of the helmet, grasp the back edge, and pull forward. If you can roll a helmet off with the strap secured, you are advised to keep looking.
Bruce Porter, of Arai helmets, reports a frightening trend towards young riders leaving the chinstrap loose while riding, so a rider can lift the helmet up onto his forehead at stop signs. Not having the helmet secure and the chinstrap snug is an invitation to the helmet coming off during an accident, with the rider losing whatever protection it would have offered.
Once a helmet has been involved in an accident, it should be retired. It’s done its job. Even if the helmet only has a few minor scratches on the outside, there are probably delamination cracks inside the shell, and a partially crushed foam liner under the padding. So, even if it doesn’t look damaged, it should be retired or at least sent to the manufacturer for inspection. But what about a helmet that’s just getting on in years? When should you retire a helmet that hasn’t been involved in an accident?
A common recommendation is to replace a helmet every two years if worn regularly. Arai helmets have a five-year warrantee, the longest in the business. If you don’t have the patience to take care of your helmet, or if you can easily afford replacement every two to five years, that’s good advice. But most of us are reluctant to put a $500 lid in early retirement as long as it’s still useful.
If we follow a few common-sense rules of care, a helmet can retain most of its performance capability for years. Jim Tatung of Gerard Design paints helmets, and knows them inside out. Jim personally uses helmets that are more 7 years old, but he is very careful about taking care of his helmets.
Over the years, the University of Southern California Head Protection Research Lab has run aging helmets through the same standards they were originally rated for, to see how they have survived old age. Amazingly, older helmets often pass their original tests, including some 25-year-old antiques. HPRL’s David Thom suggests that there are only a few “old” helmets to be concerned about, such as the 1970s vintage polycarbonate shells, and some helmets made to the SNELL standard in 1985 and 1986.
So, the good news seems to be that quality helmets can provide protection for many years if cared for. However, most of the experts we talked to also suggested that helmet technology is progressing rapidly enough that you will probably want to upgrade to a newer design every few years. According to the laboratory tests, newer helmets offer much better protection that those of 10 years ago. And a quick look at today’s helmets will also confirm that features such as quick change faceshields and air circulation vents are light years ahead.
Remember how a helmet works—the important part is the foam liner. We’re not talking about the fabric comfort pads, we’re talking about the crushable Expanded PolyStyrene (“Styrofoam™”) liner glued inside the shell. It is relatively easy to poke unseen craters in the EPS liner by jamming the helmet onto a pointed object such as a mirror or sissy bar, so you should make a point of avoiding that bad habit. Either hang your helmet by the strap, or park it on the ground. And if you are carrying a spare helmet, put it in a helmet bag, and strap it on the back of the saddle.
Porter has two common sense tactics and a “hot tip” for helmet care:
· Let your helmet “breath” for a day after use, to let it dry out.
· Clean the inside with soap and water to remove perspiration, acids, and dirt.
· When not using his helmets, Porter places a non-scented anti-static clothes dryer sheet inside to help absorb odors.
Thom suggests periodic inspections of the EPS liner. The liner surface should be clean, smooth, and free of dings or cracks. And, as a general guideline, never park your helmet anywhere you wouldn’t park your body.
Getting The Vapors
All petroleum vapors tend to unglue EPS, so avoid parking your helmet over any source of solvents or fuels. Arai’s Porter suggests that perching your helmet over the gas tank vent on your motorcycle for just one hot afternoon could kill the EPS liner.
For the same reason, it is very important to protect the EPS from paint solvents if you choose to have your old helmet repainted. Both Porter and Tatung suggest that you leave helmet painting to the specialists. It is critical to carefully mask off the liner plus any exterior vents, and also to use “high volume low pressure” (HVLP) equipment in a ventilated spray booth that will quickly carry away the vapors. If you aren’t convinced that paints dissolve Styrofoam, Jim suggests pouring a little lacquer thinner in a Styrofoam cup and observing the results.
Be aware that there are fake “novelty” motorcycle helmets being marketed. You may even see them for sale at motorcycle events and at motorcycle dealers. It is illegal to sell such helmets for motorcycle use, but some riders seem to prefer flaunting the law, and some unscrupulous sellers provide fake DOT stickers to help the rider argue compliance with mandatory helmet laws. We’re not taking sides here, but It’s important to understand that a flexible plastic bowl with no internal crushable liner cannot provide even minimal brain protection.
The one feature which helmet manufacturers have yet to add, is passive hearing protection. Wind noise around a rider’s head at freeway speeds is loud enough to damage hearing, but helmet manufacturers have yet to build a passive wind noise reduction system into a standard motorcycle helmet. Of course, helmet manufacturers have to walk a tightrope between hearing protection and traffic safety. Until we begin to see noise reduction built into motorcycle helmets, earplugs are the sensible approach to protecting your hearing.
Eye protection is important not only because the eyes are easily injured in an accident, but also because debris in the eye may be so distracting that the rider loses control. Most states require eye protection, either directly over the eyes, or as a windshield mounted to the motorcycle.
Eye protection for a motorcyclist should be shatterproof. Sunglasses with glass lenses are not a good idea for motorcycling because when a glass lens is struck by a hard object, chips pop off the inside surface, directly into the eye. If you must wear prescription eyeglasses, they should be worn under shatterproof protection. Most states with eye protection laws specify the VESC-8 standard.
The Bottom Line
The bottom line with crash-resistant riding gear is that you won’t have time to get it out of the top box and put it on in the instant just before your number comes up. Let’s face it: crash-resistant gear usually means stiff, heavy, uncomfortable armor. It’s always a temptation to leave off the serious gear for a short ride. But if you take the time and effort to find riding gear that is practical and comfortable, you are more likely to be wearing it every time you ride. And if you always wear a good helmet, you’re a lot more likely to come out of a little accident without permanent brain damage.
From the standpoint of someone whose number has come up a couple of times over the years, I can assure you it’s worth the trouble and expense.
David Hough is a long-time motorcyclist and journalist. His work has appeared in numerous motorcycle publications, but he is best known for the monthly skills series “Proficient Motorcycling” in Motorcycle Consumer News, which has been honored by special awards from the Motorcycle Safety Foundation. Selected columns were edited into a book “Proficient Motorcycling” published by Bowtie Press. He is also the author of “Driving A Sidecar Outfit”. A pocket handbook, “Street Strategies” is currently in the works.
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