Yep, as Meanie wrote, I'd say more info may lead you to reconsider your thoughts on this.
From the info given to me and my experience the shell (primarily fiberglass/kevlar/carbon composites; or thermoplastic alloys, and even newer polycarbonates nowadays) can EASILY withstand a drop from several feet on a hard surface when UNWEIGHTED (i.e. YOUR HEAD IS NOT IN IT with your body attached which adds MORE weight plus leverage to the impact).
Some additional background:
In a normal crash situation, it's the momentum (speed of bike, and weight of your head and body) that the external shell transfers to the internal liner and causes the main damage to the helmet: the INTERNAL liner once compressed may not protect your head adequately a second time around, AND it's only a portion of that liner which is compromised. So it's sort of like playing russian roulette after that. You raise the odds against you.
Of course the harder the crash the more damage to the external shell will occur, OR if it hits a fairly sharp object (as it's ability to spread the load is pushed to the limit here - i.e. sharp pointy rocks could really test a helmet -- it's the same as being hit with a fist/foot or the point of a knife or pen --ouch! puncture!)
The shell can certainly be compromised and damaged, but think about it logically. You can always test a little with an old helmet too
just for kicks. Also I'd say some more experience in crashing (I'll get to that in a minute
) will go a long way to changing your thoughts on this.
Often you can feel the compressed area of the helmet liner after a hard crash. It' really a very simple device. It's primarily the internal polystyrene liner which compresses allowing more time to abosorb the load and decelerate thus saving your head.
It's helmet uses muc the same basic principals as a packing box for a monitor or other electronic component. a) box, b) polystyrene. Try punching, kicking, abusing the "styrofoam" liner in the packing box. The liner in a helmet is similar, but "tuned" for it's intended purpose (speed, weight, head, etc.)
The outer shells of helmets are quite durable and in my experience (primarily roadracing, but also off-road riding (including few races), ice racing, street etc... over 15 years in total) + several years working in the motorcycle industry, speaking directly to helmet reps, etc. (yada yada yada).. and having crashed multiple times while roadracing, and off-road, and a few on the street, etc.. and seen several peoples lids after crashes, etc... One of my last crashes resulted in a concussion... and having thrown away several helmets from a various crashes. It is more difficult to detect damage to the outer shell, but the outer shell is much more durable than the inner liner, so basically what I am saying is that when you have an impact that makes you think twice, or you have a couple smaller impacts than by experience you can gauge when to toss it out. Better safe than sorry for sure, but don't go over the edge with the "i dropped it, it's toast" idea. It's very wrong, and if I felt a helmet was to be tossed after a small drop, i certainly wouldn't trust the damn thing on my head in an REAL crash situation. think about it. This isn't the 60s. Just as the bikes have improved dramatically, so has all the gear. Helemts are simple in concept but have a great deal of refinement and technolgy behind them.
i think you will find that you need to do a retake on your thoughts on helmet construction, crashes, etc.. the reality in my opinion is very different from what you are thinking.
The majority of my helmets were Arai, with a few Shoei's... because FIT is also important in day-to-day comfort as well as a helmets ability to protect in a crash. It's better to regret throwing away an Arai, rather than having a brain injury. $500 is CHEAP insurance, and so is $1000. The day-to-day comfort is also AWESOME, plus really excellent visors, etc... overall quality.
Here's an important quote from that bit from the Snell article which reiterates what I am saying, "A motorcycle helmet works by crushing the expanded polystyrene (EPS, or Styrofoam) layer, absorbing and slowing down the impact. If a helmet doesn't slow down the impact, the energy gets transmitted to the skull and brain inside and to whatever it hits."
anyway. long post, but i feel it's justified. hope it gives you something to think about. Consider checking out the helmet manufacturers web-sites, and other GOOD sources of info, like Snell, DOT, CE (European spec) info... etc. i think in the UK there is another helmet safety certification as well, something like BFA as I recall.
//monkey
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