How high up can you drop a motorcycle helmet from before it is deemed unsafe?

Answer 1

Motorcycle helmets are only good for one drop. It doesn't matter if you can see the damage or not, a SNELL certified helmet is only certified for one drop. The damage you don't see may cause your helmet to shatter like an eggshell when you really need it.

AnswerI recently watched a program on TV re: helmet testing and certification procedures. I don't know the height, but if a helmet is damaged/cracked, it is unsafe. If the lining is removed/damaged, it is unsafe. The testing and certification of a helmet requires that it withstand a 13 ( or 16 ) MPH impact. That is equivalent to sitting on your motorcycle and falling over sideways and hitting your head on the road. Then, you ask, what happens if I am in a collision at 20MPH? I'm afraid I can't answer that, but they did say that there is a "skid factor" involved. From what I understand, the fact that you fall off your motorcycle at 20 or 60MPH makes no difference. The height doesn't change, unless you are launched higher by a considerable distance, over your normal head height. Therefore, the impact of the helmet on the ground is no more than a straight drop from normal height. So, to make it short, you can drop a helmet from any distance, as long as the integrity of the helmet is not compromised, as in cracked, misshaped or damaged in any way. As far as how far you can drop a helmet, while being worn, I wouldn't suggest an impact of anything more than the testing certification of 13-16MPH. I believe that is equivalent to about a 10 foot drop. AnswerFrom the Snell website:

"Helmets are normally comprised of four elements; a rigid outer shell, a crushable liner, chin straps or a retaining system and fit or comfort padding. The rigid outer shell when present adds a load-spreading capability, and prevents objects from penetrating the helmet. It's kind of like an additional skull. The liner, usually made of EPS (expanded polystyrene) or similar types of materials absorbs the energy of an impact by crushing. The chin strap when properly buckled and adjusted along with the fit padding helps the helmet remain in position during a crash. Helmets work kind of like a brake or shock absorber. During a fall or crash a head is traveling at a certain speed. Since the head has weight, and is moving there is a certain amount of energy associated with the moving head. When the helmet along with the accompanying head impact an unyielding object; a rock, a wall, a curb or the ground the hard shell starts by taking the energy generated by the falling helmet (head) and spreads it over a larger portion of the helmet, specifically the internal foam liner. The foam liner then starts to crush and break which uses up a lot of the energy, keeping it from reaching the head inside. Depending on how fast the head is traveling, and how big, heavy and immovable the object is the faster the head slows down, and the more energy is present. In short everything slows down really quickly. A helmet will effectively reduce the speed of the head by breaking and crushing which reduces the amount of energy transferred to the brain. The whole process take only milliseconds to turn a potentially lethal blow into a survivable one."

Because of the different layers involved in how a helmet reduces the impact of an accident, coupled with the fact that the part that absorbs most of the impact is not even visible, a drop of anything higher than 1 - 2 feet onto a hard surface can, effectively, render a helmet useless as protection in an accident - even if there is no visible damage.

AnswerIn addition to the above, helmets deteriorate over time due to the effects of weather and heat/cold damp/chemical exposure. Their life is approx five years(varies by manufacturer and model). The probability of helmet survival from dropping also diminishes over time.

Answer

It is designed to withstand one impact from over four feet with your head inside. If there is nothing inside the impact absorbing liner (Single or Dual Denisity Foam) would not be compressed by the drop. It might scratch the outer (Painted) shell but as long as the shell is not cracked you would be okay. ALL testing (DOT, SNELL, or EEC) involves a drop with a head shaped weight inside not a empty helmet.