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  1. #101
    Hugh Conway Guest
    Quote Originally Posted by DudeLebowSKI View Post
    Exactly. It won't help.
    yeah, speed doesn't make a difference 28mph is half the energy of 40mph.

  2. #102
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    Quote Originally Posted by Hugh Conway View Post
    yeah, speed doesn't make a difference 28mph is half the energy of 40mph.
    Dead is dead as far as I'm concerned and that's basically what helmet manufacturers are saying about their helmets, concussions and speeds over 15km/hr which incidentally is in the ballpark of 10 mph.
    ;-)
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  3. #103
    Hugh Conway Guest
    If you want to play the juvenille fatalist game of TGR have at it; but that's not what they are saying at all. There's a world of difference between dead, a TBI, or "just" a concussion. Sure it's fun, take the risks - I have and do. It's what makes it fun to me. But be fucking honest about it, if you can. 40mph is 16 times the energy of 10mph. you don't think that makes a difference?

  4. #104
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    Quote Originally Posted by Hugh Conway View Post
    If you want to play the juvenille fatalist game of TGR have at it; but that's not what they are saying at all. There's a world of difference between dead, a TBI, or "just" a concussion. Sure it's fun, take the risks - I have and do. It's what makes it fun to me. But be fucking honest about it, if you can. 40mph is 16 times the energy of 10mph. you don't think that makes a difference?
    You are calling me juvenile? That's a laugh. Anyhow, all I am saying is that even the average shitty skier travels much faster than today's current helmets are rated for. Yes, moving at 40mph generates more energy than 10mph. Congratulations on your grasp of the obvious. I am saying that beyond a certain threshold, which is currently extremely slow, it doesn't matter in relation to what the helmet was meant to do.

    You are the guy constantly complaining about marketing dribble. I am on your side dude. Why is everything a confrontation with you?
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  5. #105
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    don't crash = win
    Quote Originally Posted by blurred
    skiing is hiking all day so that you can ski on shitty gear for 5 minutes.

  6. #106
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    Quote Originally Posted by DudeLebowSKI View Post
    Dead is dead as far as I'm concerned and that's basically what helmet manufacturers are saying about their helmets, concussions and speeds over 15km/hr which incidentally is in the ballpark of 10 mph.
    ;-)
    That's really far from the whole story: 15 kph to 0 in a single impact is one test, but it's mostly worthwhile for the analogy it provides, since obviously no one expects the helmet to see that specific impact very often. The analogous impacts are quite frequent, though. One specific commonality being the net change in velocity. You remember that velocity is a vector, not a magnitude, of course. This means speed and direction. So when you impact something and glance off with a net change in your head's velocity of less than that 15 kph to zero test, the helmet might help you keep the acceleration acceptable for your brain. Of course, you also remember how to apply the correct trig function to see how the range of angles from straight on impact at 15 kph to virtually parallel allows for a higher relative speed if the velocity is not perpendicular to the impacted surface, so I won't belabor the point. But given these facts and the above thread it should by now be casual to the most oblivious observer that a) helmets cannot prevent concussions in all circumstances, since we won't ski in such a way as to guarantee only sub-fifteen kph changes in velocity or don giant bubbles; and b) helmets have a good chance of reducing or preventing some fraction of concussions when compared to bare heads in the same impacts, where such fraction falls as a function of speed if impact angle is assumed to be a random variable with some fairly constant distribution throughout the range between 0 and 90 degrees.

    Or we could use common sense and just say the crushable hard hat might help and it might not; depending on just how well the brain it's protecting is protecting itself. Reduced risk is not safety, but it's still reduced risk.

  7. #107
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    I think the point missed is that all the vector and velocity math is irrelevant because hardly anybody skis at speeds within the threshold that wearing a helmet will assist in decelerating the brain enough to reduce concussion. That's the problem with the current perception of helmet use. Most people don't realize a ski helmet's limitations. I would agree with your points with some tiny adjustments:

    Quote Originally Posted by jono View Post
    a) helmets cannot prevent concussions in 'most' circumstances, since we won't ski in such a way as to guarantee only sub-fifteen kph changes in velocity or don giant bubbles; and

    b) helmets have a 'slight' chance of reducing or preventing some fraction of concussions when compared to bare heads in the same impacts, where such fraction falls as a function of speed if impact angle is assumed to be a random variable with some fairly constant distribution throughout the range between 0 and 90 degrees 'and the skier is skiing at an extremely low velocity.'
    I am not anti helmet. I wear one all the time... I just wear it with a realistic expectation of it's abilities.
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  8. #108
    Hugh Conway Guest
    You have a realistic assessment that it's useless above 10mph? WTF?

    Schumacher's alive, now, because he was wearing a helmet. He'd have been a beaver hat without it.

  9. #109
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    Quote Originally Posted by Hugh Conway View Post
    You have a realistic assessment that it's useless above 10mph? WTF?

    Schumacher's alive, now, because he was wearing a helmet. He'd have been a beaver hat without it.
    No. Like I said, I don't have proof of the standards testing criterion. I remember reading it in a helmet issue of powder mag a few years back. That's why in my earlier posts I said that I could be wrong. Either way I remember the testing threshold for velocity being shockingly low. Much much lower than I felt most people ever skied at. As for Schumacher, claiming he's alive because he was wearing a helmet 'might' be true. I'm glad he is ok but that's not exactly a scientific claim. Maybe he was moving quite slow through that boulder field. Either way, I'm not saying helmets are useless. I'm just saying that manufacturers are overstating their effectiveness and praying a little bit on naive consumers.

    Oh and here's your gratuitous 'WTF?' back at ya. Cheers.
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  10. #110
    Hugh Conway Guest
    Quote Originally Posted by DudeLebowSKI View Post
    As for Schumacher, claiming he's alive because he was wearing a helmet 'might' be true.
    < shrug > it's a quote from his doctor's I believe.

    I got your point long ago. You've exhausted it's merit. I used to have that argument. Almost a decade ago. Yes, there's lots of dipshits on chairlifts who won't ski trees without a helmet. They are dipshits.

  11. #111
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    I actually, I don't need to remember where I read the testing stats. The undeniable math behind G force tolerances of our brain and deceleration distance is brilliantly outline by Jono. And this is using a very generous estimate of 10m/s.

    Quote Originally Posted by jono View Post
    Linear deceleration is as good as it gets for a given change in speed, but a tangential bounce off the snow reduces the total change in speed vs. a full stop straight into a tree. Not sure which was intended when talking about adjusting the math, but thought that worth clarifying. To refine it a hair, the lowest concussion acceleration could be 15-20 g's, and I don't think you can expect survival above about 80 sustained. IndyCar reported a spike over 100 a long time ago but it was ridiculously brief, not milliseconds, and the accelerometer wasn't helmet mounted AFAIK, so real value at the helmet was certain to be lower. Driver survived, can't imagine it was without a concussion, though.

    Anyway, if you're willing to live with 10m/s impacts you'd need ~12 cm of linear deceleration with no bounce back to stay in that survivable area, say 40 cm (?) to avoid a concussion. Bounce back at 5 m/s the other way and you might as well have hit at 15. So the helmet needs to permanently deform on impact or you need to use 2-3 times as much thickness. At what point does your giant helmet start causing neck injuries or even avoidable head injuries because it hits stuff your head would have missed? I know that starts to be rog's argument with ANY helmet, but realistically you would have to address that if you're going to start selling Gary Busey's helmet protector protector for actual use.
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  12. #112
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    Quote Originally Posted by Hugh Conway View Post
    < shrug > it's a quote from his doctor's I believe.

    I got your point long ago. You've exhausted it's merit. I used to have that argument. Almost a decade ago. Yes, there's lots of dipshits on chairlifts who won't ski trees without a helmet. They are dipshits.
    I get your point as well although I don't see how math can have it's merit exhausted. My kids wear helmets because it's a better idea than not. There I said it. Anyhow, I think I am going to go back to spending more time on my firearms forum. I'm scared of those fuckers and therefore don't spend as much time arguing. Cheers Hugh.
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  13. #113
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    I guess this is all down to the particulars of what we think is a "slight" improvement in safety, but given the insistence that the testing speed is the fastest speed at which helmets are effective I get the impression you're missing the point with respect to how effective helmets are going to be anytime you have an impact that does not result in a dead stop. I'm only saying that because you refer to 15 kph as a 'threshold speed.' You could be going 100+ miles an hour down any icy louge run and bounce off the ice at a slight angle and a helmet would be very helpful. So in reality it's more like 15 kph is the lowest speed at which you'd start worrying about concussions rather than an upper limit. (That's what I meant about the tangential bounce above--the reference to linear deceleration was a slightly different topic.) Anyway, I think we're pretty much into semantics on this in any decision-making sense so I'll try to give the corpse a rest.

  14. #114
    Hugh Conway Guest
    Quote Originally Posted by DudeLebowSKI View Post
    I don't see how math can have it's merit exhausted.
    you don't understand how the math is applied or what it says?

  15. #115
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    Jono, actually I like that example very much. That makes more sense to me. Like I said, I wear a helmet all the time...I was just never 100% sure 'why?' It still doesn't change the fact that helmet companies are abusing the naive nature of their god-fearing consumers and downplaying current helmet limitations. I guess that's almost 100% full circle to the OP. Peace.
    First 360 mute grab --> Andrew Sheppard --> Snowdrifters 1996

  16. #116
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    Glad that helped. FWIW I found this thread more enlightening than I expected; hadn't done that math on a helmet before specifically, and after seeing where the numbers come out with such a ridiculously thin crush zone I'm back and forth between thinking it's great that it might help in a high speed crash and remembering how easy it is to be dead even from a pretty slow impact square-on. Probably helps to remember both, I guess; it obviously has real value in risk reduction, but I can't say for sure it hasn't ever given me a false sense of security, given how real the likelihood of concussion still is. I don't need to become rog's case in point.

  17. #117
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    Typically, when crashing, do you go full speed head first into an obsticle? Sure, if you complete half your flip in the terrain park and go skull to hardpack... or maybe an avalanche takes headfirst you into a tree at 30mph.

    Typically, a concious person in a ski fall will attempt to arrest their fall and to not be head first. Example, you started at 30mph, caught an edge, tried to plant your skis and slowed to 15mph when your legs hit the tree, and you rapidly decelerated to 5mph before flipping over your fractured leg and planting your head into the wood.

    Every fall is different. Try not to crash hard.
    Quote Originally Posted by blurred
    skiing is hiking all day so that you can ski on shitty gear for 5 minutes.

  18. #118
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    I've looked around the web quite a bit to help pick a helmet - seems to me that the bulk of the evidence shows that helmets will reduce the incidence of concussion but are far from preventing them. I almost exclusively backcountry tour and I noticed that ski mountaineers use climbing helmets: lighter and protect from similar hits. I roast easily and don't use goggles so ski helmets don't offer much benefit. Has anybody else looked into these? Any thoughts? Was also wondering if anyone has seen a study showing the success of MIPS design in ski helmets to reduce rotational impacts.

  19. #119
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    skiing within yer skill set and at reasonable speeds per the conditions trumps skiing beyond ability level with a walnut on to protect the noggin. don't crash. at all. it happens, but there's no reason to let it happen if yer in control. this has nothing to do with pushing yer boundaries or some bullshit like that. speed isn't progression. skiing well in all conditions under control is. speed comes with that progression. progression of ones skiing should be a well thought out gradual process over many many seasons.

    rog

  20. #120
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    do you sell helmets rog or do you just tell people to ski slow?
    Lee Lau - xxx-er is the laziest Asian canuck I know

  21. #121
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    Quote Originally Posted by jono View Post
    That's really far from the whole story: 15 kph to 0 in a single impact is one test, but it's mostly worthwhile for the analogy it provides, since obviously no one expects the helmet to see that specific impact very often. The analogous impacts are quite frequent, though. One specific commonality being the net change in velocity. You remember that velocity is a vector, not a magnitude, of course. This means speed and direction. So when you impact something and glance off with a net change in your head's velocity of less than that 15 kph to zero test, the helmet might help you keep the acceleration acceptable for your brain. Of course, you also remember how to apply the correct trig function to see how the range of angles from straight on impact at 15 kph to virtually parallel allows for a higher relative speed if the velocity is not perpendicular to the impacted surface, so I won't belabor the point. But given these facts and the above thread it should by now be casual to the most oblivious observer that a) helmets cannot prevent concussions in all circumstances, since we won't ski in such a way as to guarantee only sub-fifteen kph changes in velocity or don giant bubbles; and b) helmets have a good chance of reducing or preventing some fraction of concussions when compared to bare heads in the same impacts, where such fraction falls as a function of speed if impact angle is assumed to be a random variable with some fairly constant distribution throughout the range between 0 and 90 degrees.

    Or we could use common sense and just say the crushable hard hat might help and it might not; depending on just how well the brain it's protecting is protecting itself. Reduced risk is not safety, but it's still reduced risk.
    I have crashed many times without a ski helmet and lived. Rare ski crash is flying into a cement wall to a dead stop. 10mph or not, having a helmet on is much, much safer for all sorts of wipeouts. Now that I am older I also wear pads on hips, and a backpack with a spine protector plate - have it for biking anyway. Does not bother me, and every bit helps.

    As far as "better" helmets - I am not a big believer in all the marketing mumbo jumbo. They all work fairly well, if they cover your head and have sufficient crushable padding. I am happy that my kids refuse to get on the slopes on on the bike without one, and looks, weight and ventilation etc. certainly helps.

    Agree on the "do not crash" part. Best protection ever.

  22. #122
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    Quote Originally Posted by bilman View Post
    I've looked around the web quite a bit to help pick a helmet - seems to me that the bulk of the evidence shows that helmets will reduce the incidence of concussion but are far from preventing them. I almost exclusively backcountry tour and I noticed that ski mountaineers use climbing helmets: lighter and protect from similar hits. I roast easily and don't use goggles so ski helmets don't offer much benefit. Has anybody else looked into these? Any thoughts? Was also wondering if anyone has seen a study showing the success of MIPS design in ski helmets to reduce rotational impacts.
    I always wear my climbing helmet for summer volcano tours. Too much ventilation and nerdiness for winter skiing at the resort.

  23. #123
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    Quote Originally Posted by skimaxpower View Post
    I always wear my climbing helmet for summer volcano tours. Too much ventilation and nerdiness for winter skiing at the resort.
    OTOH I have to cover my mostly bald head and a helmet is a lot more comfortable for me than a ski cap, because of the ventilation, until it gets warm enough for a baseball cap.

  24. #124
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  25. #125
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    Occlude the IJ and this is supposed to "pressurize" the cerebral vasculature to reduce brain movement. What could go wrong?
    Quote Originally Posted by blurred
    skiing is hiking all day so that you can ski on shitty gear for 5 minutes.

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