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i like HJC

  1. #101
    Just Registered Doc's Avatar
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    Quote Originally Posted by Kham View Post
    the initial impact is the one with most energy that counts. it's not going to be spring like.

    Believe what you want but you need to study the mechanisims of injury.

    Just Fucking Google It

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  2. #102
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    Quote Originally Posted by ultraTwist View Post
    The foam is going to dampen any spring like effects.
    Even that may not be true. If the foam has already dampened the effects of the original hit, it may not be able to absorb the "spring effect" as that spot has already been compressed. But you are right cheap is cheap for reason.

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  3. #103
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    Quote Originally Posted by Doc View Post
    Believe what you want but you need to study the mechanisims of injury.

    Just Fucking Google It
    so anyone who doesn't believe as you do are all dumbass?

    how many here are dumbass?

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  4. #104
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    Quote Originally Posted by hammadown View Post
    Just remember, if your head hits hard enough to cause something relatively minor like a concussion, you are not far off from significantly more serious damage and every little bit counts. But hey its your head and your wallet.
    While this is true, if you read some of the SNELL articles on how they set up their helmet tests you'll understand why that's not the entire story.

    It has to do with the tradeoffs between lower density and higher density foam. Lower density foam is softer, which allows the liner to reduce the impact of a light blow to the head more so than a high density foam would. However, the tradeoff is that the lower density foam compresses quicker, and once the foam is compressed it transmits all the remaining forces to the head.

    What you end up with given a certain helmet thickness is a decision about whether to try and prevent against minor injuries better by using a low density foam, or trying to prevent against more catastrophic injuries by using a higher density foam. This is why most helmets will not adequately prevent concussions; they're designed to save your life instead. That means that more force is transmitted to your head in a minor crash (because the foam is harder and will not completely compress) but allows more "headroom" for severe catastrophic trauma where softer foams would fail to protect the head.

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  5. #105
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    Quote Originally Posted by Kham View Post
    so anyone who doesn't believe as you do are all dumbass?

    how many here are dumbass?
    Meow, when did I call you or anyone else dumbass?


    I refuse to have a battle of the wits with an unarmed person.

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  6. #106
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    honkie got it

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  7. #107
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    Quote Originally Posted by Honclfibr View Post
    While this is true, if you read some of the SNELL articles on how they set up their helmet tests you'll understand why that's not the entire story.

    It has to do with the tradeoffs between lower density and higher density foam. Lower density foam is softer, which allows the liner to reduce the impact of a light blow to the head more so than a high density foam would. However, the tradeoff is that the lower density foam compresses quicker, and once the foam is compressed it transmits all the remaining forces to the head.

    What you end up with given a certain helmet thickness is a decision about whether to try and prevent against minor injuries better by using a low density foam, or trying to prevent against more catastrophic injuries by using a higher density foam. This is why most helmets will not adequately prevent concussions; they're designed to save your life instead. That means that more force is transmitted to your head in a minor crash (because the foam is harder and will not completely compress) but allows more "headroom" for severe catastrophic trauma where softer foams would fail to protect the head.
    I agree completely, and I think we pretty much or on the same wavelength on this topic anyway. My point, though I perhaps didn't articulate it quite as clearly as I should have, was that in a serious crash there is a fine line between minor injuries and serious damage. In other words, it does not take a whole lot more force relative to that of a crash, to go from minor or no damage to significant problems. In such a case while all helmets, for the most part, may do a decent job at absorbing the initial force of impact, if you are walking that fine line the "lessor" contributions that may be absorbed by a more quality helmet could be the difference between tragedy and not. Again, I'm not sure my point is completely clear, and it probably doesn't matter because its not going to change anyones mind, and some small part of this is going to be nitpicked by someone anyway.

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  8. #108
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    ok if someone wants to experitment this season...

    I have an old Polycarbonate helmet (I think I still have it or we could use Buddhas old one) and an old Composite.

    We can drop them from a height and look to see which one bounces higher.

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  9. #109
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    I've got a 13+ year old Shoei I'll contribute to the testing!

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  10. #110
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    But this is still a point which seems to be lost in a lot of these discussions. The major argument against polycarbs at lrrs was that a group of people sustained non-permanent injuries (concussions, headaches, etc) from what was considered to be minor trauma.

    The point that a lot of the SNELL articles push is that, given reasonable levels of EPS lining and the state of the art, helmets can not be made to both protect against minor injury and catastrophic injury. In order to prevent permanent brain damage, you must accept a foam density which does not compress significantly from a low-G impact and therefore could potentially cause nonpermanent injury.

    In fact, I would argue that the *best* helmet for preventing permanent injury is necessarily the *worst* helmet for preventing minor injury, as the "safest" helmet in terms of permanent injury would be one that had an EPS liner which allowed exactly the G threshold before permanent injury and no more. A liner with this density would be able to absorb the greatest impact for the longest duration before transmitting a permanent injury to the riders head. However given that it would not begin compressing until this point, it would also be the least effective in preventing minor injuries.

    Of course, since there is no "magic" threshold for permanent injury, nor is there a magical material which would not begin compressing until exactly a certain G load, this sort of helmet could not exist. But I would argue that manufacturers produce, and standards organizations test for, helmets that meet the closest real world approximation of that "magic" helmet.

    In a nutshell: if you crash with a helmet, and you wake up without permanent brain damage, that helmet has accomplished it's job. Arguing about minor concussions/headaches sustained in a crash ignores the tradeoff between minor and major injury protection, and in fact a helmet which provides protection in minor injuries would in fact be necessarily less protective in a major one.

    As far as I'm aware, none of the riders injured with HJC polycarb helmets at lrrs suffered anything more than minor, nonpermanent injury. Therefore, the argument to ban/avoid polycarbonate helmets is a specious one which ignores the facts about helmet construction and design tradeoffs.

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  11. #111
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    With that said, any helmet shell design which can disperse the impact over a wider area is superior to one that does not for preventing both minor and catastrophic injury. Distributing the force across the helmet will allow more of the EPS liner to absorb the impact.

    However, I am not aware of any data that shows whether fiberglass or polycarbonate is superior to the other in distributing impact over the shell.

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  12. #112
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    Although what I think youre not taking into account is the likelihood of suffering "severe" and "nonsevere" injuries. I have no stats, but I would think the likelihood all things being equal of suffering a non-severe injury (by your definitions) would be FARRRR greater than a severe one. And the drawback to non severe injuris is that a number of them, no magical number of course, eventually LEAD to severe head problems. Ask Eric Lindros and his 9 concussions, ask Ted Johnson, who had a number of concussions, rushed back, and now is having serious health issues blamed on it. People have had to retire because they had a number of concussions and are no longer right.
    So its not, ok you might have a headache for a few days, but you most likely wont have that ONE severe injury. Ill play the odds and try to prevent the little ones that can lead to big ones, and hope and pray I never have the big one regardless.

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    Quote Originally Posted by Pookie View Post
    My favorite was you going through T2 with your eyes closed.

  13. #113
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    Quote Originally Posted by Honclfibr View Post
    But this is still a point which seems to be lost in a lot of these discussions. The major argument against polycarbs at lrrs was that a group of people sustained non-permanent injuries (concussions, headaches, etc) from what was considered to be minor trauma.

    As far as I'm aware, none of the riders injured with HJC polycarb helmets at lrrs suffered anything more than minor, nonpermanent injury. Therefore, the argument to ban/avoid polycarbonate helmets is a specious one which ignores the facts about helmet construction and design tradeoffs.
    I'd like to clarify the LRRS/HJC debate. Ever since I can remember (and this goes back at least to when I started racing in 1987) the rule specified a "Fiberglass motorcycle racing helmet that meets both DOT and Snellxx standards." At the time and up until about 2-3 years ago polycarbonate shell helmets did not pass the Snell tests and therefore did not have the Snell sticker inside the liner. Then around 3 years ago HJC and other brands designed polycarbonate shell helmets that do pass the Snell tests and do have the Snell stickers inside the liners. These Helmets were never designed for competition and even HJC stated so in a letter to LRRS. What brought this to our attention was that we had 5 major head injuries in a row where all 5 riders were wearing HJC brand helmets, and the impacts reported by the riders and corner workers who the witnessed the crash said the impacts look fairly routine. What we didn't know at the time was that the HJC model they were wearing were the polycarbonate shell models. At first it looked like HJC itself was the problem, how ever after some investigation, (yes Jerry Wood, our safety director, actually does work hard to learn the facts and improve safety for every one) was the helmets were never designed for competition, they were design to meet a price point with DOT and Snell approval for street use only. (While I agree that helmet manufacturers need helmets at various price points, I whole heartedly disagree that street riders need less protection, see previous post about said Buick) So what ultimately happened was we went back to enforcing the rule already on the books, of only allowing fiberglass composite shell helmets that meet DOT, Shell, BSI and European standards. Since then we have not seen the rash of unconscious riders napping on the track. Experiences like this one, (and I've seen many similar situations like this one) is one of the reasons I will never wear a polycarbonate shell helmet. BTW the fiberglass HJC's are holding up just fine.

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  14. #114
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    I thought you were making one post on this subject, Peter?




    jk, good info

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  15. #115
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    Quote Originally Posted by Doc View Post
    ok if someone wants to experitment this season...

    I have an old Polycarbonate helmet (I think I still have it or we could use Buddhas old one) and an old Composite.

    We can drop them from a height and look to see which one bounces higher.
    That still doesn't prove anything since you don't have the mass of a human being flying behind it.

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  16. #116
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    Quote Originally Posted by l3uddha View Post
    i threw my helmet in the dumpstah
    Did it bounce?

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  17. #117
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    Quote Originally Posted by ceo012384 View Post
    I thought you were making one post on this subject, Peter?




    jk, good info
    Just getting facts straight 'mam......

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  18. #118
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    Quote Originally Posted by l3uddha View Post
    i threw my helmet in the dumpstah
    If it didn't bounce back out, it's a good helmet. You should dig it out and keep it.

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  19. #119
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    Some one just posted this to the near list and for some strange reason I thought it was appropriate for this thread.....


    The Dunning-Kruger effect is the phenomenon wherein people who have little knowledge think that they know more than others who have much more knowledge.

    The phenomenon was demonstrated in a series of experiments performed by Justin Kruger and David Dunning, then both of Cornell University. Their results were published in the Journal of Personality and Social Psychology in December 1999.[1]

    Kruger and Dunning noted a number of previous studies which tend to suggest that in skills as diverse as reading comprehension, operating a motor vehicle, and playing chess or tennis, "ignorance more frequently begets confidence than does knowledge" (as Charles Darwin put it). They hypothesized that with a typical skill which humans may possess in greater or lesser degree,

    1. Incompetent individuals tend to overestimate their own level of skill.
    2. Incompetent individuals fail to recognize genuine skill in others.
    3. Incompetent individuals fail to recognize the extremity of their inadequacy.
    4. If they can be trained to substantially improve their own skill level, these individuals can recognize and acknowledge their own previous lack of skill.

    They set out to test these hypotheses on human subjects consisting of Cornell undergraduates who were registered in various psychology courses.

    In a series of studies, Kruger and Dunning examined self-assessment of logical reasoning skills, grammatical skills, and humor. After being shown their test scores, the subjects were again asked to estimate their own rank, whereupon the competent group accurately estimated their rank, while the incompetent group still overestimated their own rank. As Dunning and Kruger noted,
    “ Across 4 studies, the authors found that participants scoring in the bottom quartile on tests of humor, grammar, and logic grossly overestimated their test performance and ability. Although test scores put them in the 12th percentile, they estimated themselves to be in the 62nd. ”

    Meanwhile, people with true knowledge tended to underestimate their competence.

    A followup study suggests that grossly incompetent students improve both their skill level and their ability to estimate their class rank only after extensive tutoring in the skills they had previously lacked.

    Daniel Ames and Lara Kammrath extended this work to sensitivity to others, and the subjects' perception of how sensitive they were.[2]

    Some more work by Burson Larrick and Joshua Klayman[3] has suggested that the effect is not so obvious and may be due to noise and bias levels.

    Dunning and Kruger won the 2000 Ig Nobel prize for their work.[4]

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  20. #120
    Just Registered Doc's Avatar
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    I suck, I am inadequate and you all are great.

    But I can be TRAINED!!!

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  21. #121
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    the only thing im arguing is a cheap HJC polycarbonate shell will protect your head in normal accident. i believe it is better chance than the skull cap. YES there are better and more expensive helmet than HJC polycarbonate.

    one thing i want to correct is my misunderstanding on the "spring like" effect. first thing that comes mind was it has to bounce twice.

    if you hit a tree head on at 100mph i don't think anything can safe you. you mostly will lowside off the bike.

    another thing- aren't those visor on the more expensive helmets made of polycarbonate?

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    Last edited by Kham; 11-09-07 at 03:46 PM.
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  22. #122
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    Quote Originally Posted by Kham View Post
    another thing- aren't those visor on the more expensive helmets made of polycarbonate?
    They could make them out of fiberglass, but that would probably be a poor move since fiberglass is opaque

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  23. #123
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    Quote Originally Posted by Honclfibr View Post
    They could make them out of fiberglass, but that would probably be a poor move since fiberglass is opaque
    i know. the face would hit a sharp object first i would think.

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  24. #124
    Lifer Pittenger5's Avatar
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    All they have to do is paint an open road on the inside of a fiberglass visor. then everyone will be sitting pretty.

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    Quote Originally Posted by Pookie View Post
    My favorite was you going through T2 with your eyes closed.

  25. #125
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    Quote Originally Posted by Pittenger5 View Post
    All they have to do is paint an open road on the inside of a fiberglass visor. then everyone will be sitting pretty.
    Brilliant! Then you can just sit in your garage imagining you're on the open road riding at high speeds, ensuring you never endanger your head by actually going anywhere.

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