Helmets - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
 
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post #1 of 1 (permalink) Old 01-17-2006, 09:53 PM Thread Starter
Vulcan Verses
 
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Helmets

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Q: I dropped my helmet on a linoleum over concrete floor from about 4.5 feet high. Full face HJC, Snell Approved. It sounded really loud! WHACK! Am I in trouble? I've heard they're good for one crash. Would this qualify as a crash?
A: Yes it does..If it was padded carpet or a lower height...I wouldn't worry about it. However , 4-1/2' to concrete..I would. If it was a polycarbonite helmet..it might not get effected ..but if it's fiberglass..there is the chance you imparted some unseen fractures in the shell. Maybe. Being unseen..how could you know for sure? The question you have to ask your self is: Do you feel lucky? do ya punk? ( sorry..been dying to have a reason to use that line...lol) I guess if it were me..I'd think about replacing it. I have seen tests on "damged" helmets..and they can loose alot of their effectiveness if there is something wrong with them. Alot of the impact in moderate crashes does rely more on the liner in the helmet than the shell. The bottom line here is - this is something you have to weigh yourself. Helmets are not cheap..but them neither is you head.... Knifemaker

A: I'm gonna be going head-to-head (bad, bad, but I couldn't resist it!) with Knifemaker on this one. Unless your head wad in the helmet when it hit the floor, there would not be any deformation of the liner because there would not be anything inside to crush the liner material, so that concern can be removed from your analysis. As to the integrity of the shell, I don't think the impact point experienced enough deformation to cause unseen damage of the magnitude where its protective capability would be compromised. To reach that point there would have to be obvious external crazing and/or cracking. My observations are based on a lifetime of experience with fiberglass boats (and repairing damage done to them) and not based on any specific expertise with helmets, but absent any visible damage to the shell, I personally would not hesitate to continue using the helmet. . . . Chris

A: Dad told me of a doctor on the msf cource who dropped his 150.00+ lightweight helmet. they told him it was ruined, he didnt believe them so he x-rayed it, it revieled unseen fractures in the shell. on the otherside though, I let my helmet roll off the bikes seat once onto pavement, I cant find a scratch or anything, maybe it hit the face shield? didnt see it, just heard the clunk when it fell from the bike. I continued using it. It was a heavy helmet and i figured i could take it, lol. but anyways this is not for advice, just information. beavis

A: I'm certainly no expert but I was thinking the same way as Chris Luhn. If there wasn't any weight inside the helmet to create a heavy force on the inside of the helmet when dropped, I would think that the polystyrene foam would not sustain any damage. If the shell isn't fiberglass or if it doesn't have any noticable damage, it just might be fine to continue using it. But don't quote me on this. Just my opinion. You'll have to use your own discretion. I dropped my brand new "just out of the box" HJC FG-23 helmet off the seat of my bike onto the asphalt and it received only minor surface scratches. I am still using it. Of course it wasn't dropped 4 1/2 feet off the ground either! Richard

A: Friend of mine bought a Concourse a year or so ago. The guy had a really cool-looking helmet with one heck of a ding in it (quarter sized) from a concrete floor drop too. He sent it back to the manufacturer who tested it. They said it was fine. If his could survive, I'm pretty sure most others would too. It's really degredation of the structure that is dangerous, not necessarily blemishing of the finish. i.e. Foam inside damaged = bad Joe - V#8013 - '86 VN750 - joe @ yunx .com Northern, NJ

A: ..I for one , am unwilling to take the responiblity of saying...go ahead and wear it..it should be OK. that tempered my post. True .. as I did memtion , the liner of the helmet is more critical than the shell. However , I have seen helmets that were "damged" although they from the outside seemed fine. Alot depends on how the helmet is made. Fiberglass boat hulls are not neccearily comparable. My old Simpson was reinforced with Kevlar..not sure if it was bullet-proof..but The guy from Simpson did tell me that because of the way they were made..it was possible to have internal fractures that were unseen on the surface. The doctor story seems possible. The thought that durring shipping and handling a helmet may have been dropped without you knowledge is perhps a bit frightening..but I wouldn't get worried over it.The odds of it being YOUR helmet are very low. I'd be more worried that the guy that assembled my motor did something wrong. Again..the decision is up to the wearer of the helmet. So far, it looks like 3 against and 1 for... You should also consider that the odds of your helmet playing a major part in saving your life are not that important if you never have a major crash...so...still feeling lucky???? Knifemaker

A: (gravitaional acceleration) = -9.8 meters/sec ^2 distance = 4.5 ft = 1.3716 meters Vf = final velocity Vi = Initial velocity Formula: Vf^2 = Vi^2 + 2(ag)d

Solution: Vf = (Vi + 2(ag)d) =((0) + 2(-9.81 m/s^2 )(-1.3716 m)) = -5.19 meters/s = -11.61 miles/hr Recalling the limited retention of my high school Physics knowledge the helmet struck the floor at 11.61 mph. Ken NJ

A: Cool...now all we need to know is the mass of the helmet and aprox how large an area made contact with the gound to figure out how many psi of pressure was exerted to the floor and helmet..... Knifemaker

A: OK, I've got a fairly good handle on it (I think). The older original fiberglass helmets were design such that the external material absorbed the impact by sacrificing its own integrity. Therefore, the "one crash" then throw away phenom. Then came the polycarbonates that withstood the degredation but acted like ping-pong balls and "bounced" more. Theoretically, they provided less impact absorption but were able to be reused after "one-crash." The newer composites try to balance the two, and the safety features depend more on the internal polystyrene (sp?) to provide the protective qualitiies. Bottom line: I'm going to continue to wear it...at least until I drop it from 5 feet! Ken Eng, how fast is that? LOL. Knifemaker, if my head were in the helmet at the time, there would have been zero mass. HA.

A: And I respect your decision. ..A good tip for those out there that wish to never have to worry about this..Treat your helmet when it's off your head as though it was a large bucket of nitro-glycerin. Be concous of how you hold it , where you set it down and what possible forces may interfere with it. I have never dropped my helmet thinking this way.( Also...the fact that it cost $$$$$$$$$$$$$$ helps to give one some incentive...lol) Knifemaker
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