Motorcyclist Magazine, February 1991
(Ed. Note. The newest version I have of this is copyright, 1988, but I think its discussion is still valid)

What You Should Know About Motorcycle Helmets

Polycarbonate. Three-quarter. Full face. Fiberglass. Helmet styles and materials vary greatly. Yet a motorcycle helmet is probably the first piece of personal protective equipment most motorcyclists reach for when they ride. It's also the most important piece of protective gear a rider can use.

Today many states don't require mandatory helmet use for all riders in their jurisdiction, yet helmet use among motorcyclists is much higher than safety belt use among car drivers. Between 40 and 60 percent of riders voluntarily wear helmets when they ride compared with only 15 percent of car drivers who use their seat belts. And the seat belt is already in the car!

A rider's skill is an important factor in preventing motorcycle accidents. Rider education programs and improved license standards and testing procedures assist in developing safer motorcyclists. But in the event of an accident, a rider's protective clothing can help minimize injuries. Protective clothing doesn't end with a help, either. Every rider should wear a face shield or goggles, gloves, over- the-ankle boots and durable, long sleeved jacket and long pants.

Since head injuries account for the majority of motorcycle fatalities, head protection is of vital importance. While even the best helmet can't guarantee complete immunity from injury, without a helmet you are up to five times more likely to sustain a critical head injury in an accident, than a helmeted rider.

Standards and Testing

Helmets actually protect your head in two ways. The outer shell resists penetration and abrasion and absorbs the large initial shock in an accident. The inner liner absorbs the rest of the shock by slowly collapsing under impact. Both the shell and the liner essentially self-destruct by spreading the forces of impact throughout the helmet material. That's why, in most cases, if a helmet has been damaged in an accident, it may be of little protective value in another mishap.

When you shop, look for stickers on the inside or outside of the helmet confirming compliance with the standards from one or several of these agencies: U.S. Department of Transportation (DOT), the Snell Memorial Foundation, or the American Nation Standards Institute (ANSI). [ed. note. ANSI compliance is less common these days]

Each organization has established rigid procedures to evaluate:

Impact - the shock absorbing capacity of the helmet
Penetration - the helmet's ability to withstand a blow from a sharp object.
Retention - the chin strap's ability to stay fastened without breaking or stretching.
Peripheral Vision - the helmet must provide a minimum side vision of 120 degrees to each side (Most people's peripheral vision is between 110 and 115 degrees).

Department of Transportation (DOT)

The DOT sticker appears on the outside, back bottom edge of the helmet. Since 1980 all adult-sized helmets must meet the DOT standard. Helmet dealers and distributors must ensure that all the helmets they sell bear the DOT sticker.

Snell Memorial Foundation

The Snell sticker is usually found on the inside lower back of the helmet. Its use is voluntary. Snell has been testing helmets since the 1950's. Their standards have been revised six times (most recently in 1985 [ed. note. There is now a new standard, 1990, I believe]) as helmet design and manufacturing techniques have improved. They attempt to reproduce, under test conditions, the circumstances that represent potential hazard to motorcyclists. For instance, Snell has begun using a more realistic penetration test. Instead of testing penetration with the needle-like projectile the other agencies use, Snell employs a steel I-beam shaped like a highway guard rail. Snell also tests the chin piece in full-face helmets.

American National Standards Institute (ANSI)

The 1979 ANSI z90.1 standard is more stringent than the DOT standard but less demanding than the Snell Foundation's requirements in terms of impact and penetration resistance [ed. note. This may no longer be true, as the DOT standard has been updated]. The ANSI sticker is usually located on the inside of the helmet. The ANSI requirement is a voluntary standard developed by a committee or representatives from consumer groups, helmet manufacturers, testing organizations and the military.

Choosing a helmet

A safety helmet consists of four primary elements:

the outer shell
a shock-absorbing liner
a comfort liner of soft foam and fabric
a chin strap or other retention system

While color, design and price may influence your decision about which helmet to buy, protection should be your first consideration. The full face helmet provides the most protection since it covers more of your face. Recent design improvements in shell material and interior ventilation have improved comfort.

The next choice in protection is the three-quarter helmet. It doesn't offer the face and chin protection that full-face helmets do, but some riders prefer it.

Helmet shells are primarily manufactured in one of two materials: fiberglass or injection molded plastic. Helmet manufacturers are constantly working to develop less expensive, stronger, and lighter materials for helmet shell construction.

The injection molded plastic helmet generally is the lightest and least expensive available today. It may also have a shorter life expectancy. Its chemical composition can be changed if it is painted or decals are applied to its surface. Damage can occur if it is stored near gasoline, cleaning fluids, or exhaust fumes. The user should read carefully any and all information supplied with these helmets.

Fiberglass helmets can be more expensive than injected molded helmets,especially if the fiberglass layers are hand laminated. Fiberglass helmets delaminate on impact to absorb shock. You can paint them or apply decals without damage. However, because they are build to absorb shock, they can also break or crack if severely impacted in an accident, a fall or even if dropped sharply onto a hard surface.

The helmet liner is made of expanded polystyrene foam (or "Styrofoam"). This is an important part of the helmet, as this polystyrene liner is non-resilient and evenly spreads the impact in an accident. The more impact energy that can be absorbed by the liner, the less there is of that shock energy to reach the head and do damage.

One look around your dealer's helmet display will convince you that nearly any color and decoration you could want on a helmet is already available. Many manufacturers are color coordinating their helmets with the newest motorcycle models. Choose a bright colored helmet for maximum visibility to motorists.

Getting the Right Fit

There's more to fitting a helmet than just buying the one that matches your hat size or guessing at small, medium, or large. Your hat size is a good starting pointer, however, if you don't know your hat size, you can use the chart below. Measure your head at its largest circumference - usually just above your eyebrows in front, over your ears and around to the back. You may need to take severely measurements to get the largest one. If your head size falls between the numbers listed, use the next largest hat size. Since some helmets are simply marked as S, M, L, or XL, you may need to contact the helmet manufacturer for size equivalencies, as they vary.

Inches	Hat Size
21 1/4	6 3/4
21 5/8	6 7/8
22	7
22 3/8	7 1/8
22 3/4	7 1/4
23 1/8	7 3/8
23 1/2	7 1/2
23 7/8	7 5/8
24 1/4	7 3/4
24 3/4	7 7/8

Here's the best way to try on your helmet:

Hold it by the chin straps. The front of the helmet should face you with the top pointing down.
Put your thumbs on the inside of the straps, balancing the helmet with your fingertips.
Spread the sides of the helmet apart slightly and slip it down over your head.
The helmet should fit snugly and may even feel a bit too tight until it's in place correctly. Be sure it sits squarely on your head. Remember, if your helmet is too large it can be very annoying to wear because it's noisy and lets in the wind. And, in the even of an accident, it may come off!
Once the helmet is on your head, make a few other checks of its fit, before fastening the chin strap.
The cheek pads should touch your cheeks without pressing uncomfortably.
There should be no gaps between your temples and the brow pads.
If the helmet has a neck roll, it shouldn't push the helmet away from the back of your neck.
With the helmet still on and securely fastened, move it from side to side and up and down with your hands. If it fits right, your skin should move as the helmet is moved. You should feel as if a slight, even pressure is being exerted all over your head by the helmet. Remember too, that a helmet gets "broken in" as you use it, so a new one should be as tight as you can comfortably wear it.
Now, with the chin strap still securely fastened and your head straight, try rolling the helmet forward off your head. You shouldn't be able to pull it off. If you can the helmet is too big.
Take off the helmet. Does your head feel sore anywhere. Are there any red spots on your forehead? Pressure points can be uncomfortable and can cause a headache after a long ride, so be sure your helmet isn't causing any. If it is, choose the next larger size or try a different brand of helmet.

If you're still unsure about the helmet's fit, wear it around the store for a while to make sure it is completely comfortable. A helmet is an important investment, no matter what its price. Be sure the one you choose is right for you.

A word About Chin Straps

Always fasten your helmet's chin strap or other retention system snugly. A helmet will do you no good if it comes off during an accident.

Replacing your helmet

Plan to replace your helmet if it has been involved in an accident. Some helmet manufacturers will inspect and, when possible, repair a damaged helmet. If your helmet has been dropped and you think it might be damaged, you may want to take advantage of this service.

Most helmet manufacturers recommend that, under normal use, you should replace your helmet every two to four years. If you notice any signs of damage before then, replace it sooner. As mentioned above, fiberglass helmets may crack or break if dropped. And, if you see any light brown spots near the rivets of a polycarbonate helmet, it is probably damaged and should be replaced.

Why replace a helmet every few years if it doesn't appear damaged? Its protective qualities may deteriorate over time. The interior padding compresses, offering less protection. The chin strap may fray or loosen at its attaching points. And the shell may be chipped or banged. Probably the best reason, however, is the constant improvements in design and protective qualities of helmets. Chances are the helmet you buy in a couple of years will be better than the one you have now - even if the cost is about the same.

Since 1974, all helmet manufacturers must stamp the month and date of production on the helmet's chin strap. If you can't remember when you bought your present helmet, just check the strap. If there's no date at all, you definitely should replace your helmet now.

Tips on Helmet Care

Follow the manufacturer's direction on caring for your helmet. Use only the mildest soap recommended. Avoid any petroleum-based cleaning fluids, especially if you own a polycarbonate helmet. Exposure to strong cleaning agents can cause the polycarbonate helmet to decompose and lose protective value.

Never hang your helmet on the motorcycle's mirror, turn signals, or sissy bar. The inner liner can easily be damaged from such handling and may lose its protective qualities. In fact, avoid carrying a spare helmet on your cycle, unless it's carefully protected or on your passenger's head. Even the bumps and jarring from normal riding can easily damage a spare helmet carried on your cycle.

Before you do any of your own helmet decorating, such as painting, pinstriping,or applying decals, check the manufacturer's recommendations. Follow them closely.

If you plan to use a CB radio when you ride, find a model that doesn't necessitate drilling speaker holes in your helmet. Even a tiny hole can spread and weaken the helmet's structure. Before you purchase your speakers, check your state's laws regulating their use in helmets. Some states prohibit them altogether.

Retroreflective Helmets

Many states require a specific amount of retroreflective material on a reflective helmet. Check with your dealer to be sure the helmet you plan to purchase meets the requirements or won't be damaged if you apply retroreflective tape to it. Your local motor vehicle department can give you exact information on the location and number of square inches, of retroreflective material required in your state. The Motorcycle Safety Foundation has two styles of retroreflective decals available for use on helmets.

There are many considerations when deciding which helmet to buy. Talk with an MSF-registered motorcycle safety instructor, your local motorcycle dealer, other riders, and consult recent motorcycle enthusiast magazines for the most up-to-date information to help in your decision.

Remember,
People are more violently opposed to fur than leather because it's safer to harass rich women than motorcycle gangs.