The most important part of a helmet is an expanded polystyrene (EPS) foam liner (which resembles Styrofoam) That is like those white packing box material when you buy a TV from Walmart. This EPS actually absorbs the energy of an impact. DOT standard requires 1 inch thickness of it.
In a crash, the polystyrene is permanently crushed, so if you hit your head with your motorcycle helmet on, the helmet is no more use to you than a baseball cap. The helmet may look just fine externally, perhaps just a small scratch, but it probably no longer has impact-absorption in that area. The important points that a motorcycle helmet should protect, according to the Snell institute, are the crown of your head, your temples particularly right behind your eye socket, and your jaw.
Your helmet should be replaced every 3 years. This makes sense when you understand that plastic foams do break down over time, just from exposure to sunlight. So make sure you replace you helmet on that timescale and more frequently. It is very simple to say. You get the white packing foam after you buy a TV and put it aside for 3 years in your garage. See how fragile it can become.
Wednesday, December 23, 2009
Motorcycle Helmet Polystyrene Liner to absorb energy
The liner of the helmet is a very functional component and is designed to absorb and disperse an impact so it's not all directly transmitted to your skull. The shell will absorb a certain amount and this is the reason that it's not necessarily a bad thing to crack a helmet in a crash.
The liner is often made from expanded polystyrene, which is liked those white-colored packing material inside new TV or DVD sets in stores, acting against shocks too during the delivery. It works the same to the head too. However, different manufacturing techniques are used by different companies to get the greatest possible dispersion of impact forces. Helmets meeting the minimum federal safety standard (DOT) have 1-inch thick inner liner of appropriate firm polystyrene foam. Always, the inner liner is not visible. Unsafe helmets normally contain only soft foam padding or a bare plastic shell with no foam at all.
The density of this liner can not be too soft or too hard. DOT & ECE requires thicker liner than SNELL somehow. If you crash and hit your head the outer shell may look fine but the liner may have had to absorb the impact and by doing so the polystyrene may have been greatly compressed.
If there is a subsequent impact the liner will not be able to absorb or compress to the same degree and if the polystyrene is completely compressed it will offer no benefit and the forces will be transferred to the rider's head which may result in serious concussion.
The liner is often made from expanded polystyrene, which is liked those white-colored packing material inside new TV or DVD sets in stores, acting against shocks too during the delivery. It works the same to the head too. However, different manufacturing techniques are used by different companies to get the greatest possible dispersion of impact forces. Helmets meeting the minimum federal safety standard (DOT) have 1-inch thick inner liner of appropriate firm polystyrene foam. Always, the inner liner is not visible. Unsafe helmets normally contain only soft foam padding or a bare plastic shell with no foam at all.
The density of this liner can not be too soft or too hard. DOT & ECE requires thicker liner than SNELL somehow. If you crash and hit your head the outer shell may look fine but the liner may have had to absorb the impact and by doing so the polystyrene may have been greatly compressed.
If there is a subsequent impact the liner will not be able to absorb or compress to the same degree and if the polystyrene is completely compressed it will offer no benefit and the forces will be transferred to the rider's head which may result in serious concussion.
Saturday, December 12, 2009
DOT Motorcycle Helmet Buying Tips
Motorcycle Helmet Tips
Below we have provided you with a list of motorcycle helmet tips for choosing a helmet that perfectly suits your head and your riding experience:
1. Try on motorcycle helmets for at least five minutes to detect bothersome areas. Look in the mirror for symmetry, to ensure that the helmet rests just above your brows and to see if any red marks remain after taking off the helmet.
2. After you have purchased your helmet, try not to store in a high or unsteady place where it could come crashing to the ground (such as the motorcycle saddle or side of the mirror. Don't risk scratching or busting an expensive motorcycle helmet.
3. Observe motorcycle helmet safety standards. If a cheap motorcycle helmet has not been Snell certified, for example, or is not a DOT approved motorcycle helmet, your insurance company may refuse to provide accident coverage.
4. Make sure your helmet has undergone anti-scratch and anti-fog treatment. In addition, be sure the visor doesn't touch the helmet outer shell resulting in scratches or fuzzy vision areas on your visor.
5. A lighter helmet may be more comfortable than its heavier counterpart, but is perhaps less equipped to ensure motorcycle safety.
6. Consider your chinstrap while checking your motorcycle helmet--the strap should not be too long and should be able to be tucked away so as not to hit your chin repeatedly.
7. Poor ventilation systems are chief causes of noisy helmets. The more aerodynamic the helmet and the better the vents, the less noise there will be.
8. A motorcycle helmet's comfort liner can mold a bit to the shape of your head so the helmet typically becomes more comfortable over time and use. Be sure, however, that you start with a good fit.
9. Inquire about the motorcycle helmet safety standards the motorcycle helmet manufacturer has met. A cheap motorcycle helmet may eschew certain safety testing standards. Moreover, always observe motorcycle helmet law by state, particularly if you are a young rider.
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