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From: Zen Cycle <funkmaster@hotmail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Helmet efficacy test
Date: Thu, 27 Mar 2025 16:14:57 -0400
Organization: A noiseless patient Spider
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On 3/27/2025 1:13 PM, Frank Krygowski wrote:
> On 3/27/2025 8:11 AM, Zen Cycle wrote:
>> On 3/26/2025 11:28 PM, Frank Krygowski wrote:
>>> On 3/26/2025 3:57 PM, Zen Cycle wrote:
>>>> On 3/26/2025 11:47 AM, Frank Krygowski wrote:
>>>>>
>>>>
>>>>>>> Trouble is, the protection from a bike helmet is far, far less 
>>>>>>> than people are led to believe. Look up the standardization test.
>>>>>>
>>>>>> "led to believe" by what metric? I've never seen any literature 
>>>>>> claiming a helmet _prevents_ serious head trauma.
>>>>>
>>>>> WHAT???
>>>>
>>>> No helmet manufacturer or helmet advocacy group claims helmets 
>>>> _prevent_ serious head trauma. They _can_ reduce severity, not 
>>>> prevent it.
>>>
>>> Seems to me you're focusing on the difference between "_always_ 
>>> prevents" (which was never stated by anyone) and "can reduce severity."
>>
>> Yes, I am.
>>> The latter is more honest, but is NOT how helmets are promoted.
>>
>> So you're saying helmets are promoted as preventing serious head 
>> trauma, yet your only "evidence" is:
>>
>>> Try googling "Do bike helmets prevent serious head trauma?" After 
>>> reading AI's "Yes" try follow the resulting links.
>>>
>>> And logically, if a helmet did prevent serious head trauma in one out 
>>> of ten cases, that would justify a "Yes" answer. In those cases a 
>>> helmet would have done what was asked.
>>
>> Yet there is no published literature from any manufacturer or advocacy 
>> group which supports your claim 'thats how helmets are promoted'. an 
>> AI answer does not qualify as marketing literature.
> 
> I don't have a stock of marketing literature, but I suppose we can both 
> search online. There's this: https://sonomasaferoutes.org/sites/default/ 
> files/lesson_7.pdf  that states "Why Are Helmets Important? (10 minutes)
> • Ask students to articulate why wearing helmets is important (because 
> they protect against brain injury, disability, and death). Share that 
> helmet use has been estimated to reduce brain injury risk by 85 percent."

OK, you came up with one source - I'll give you that.

> 
> So "they protect against brain injury, disability, and death" (with the 
> never corroborated "85%" that's been disallowed in U.S. government 
> publications). Perhaps you'll now say "That's not _exactly_ the same 
> wording?"

We can have a semantic discussion over "protect against" vs "prevents". 
My view is "prevents" is absolute, "Protects against" is not and is more 
in line with "_can_ reduce severity". Your interpretation will likely vary.

WRT the 85%, again, this is the first I've heard of anyone promoting 
that. They shouldn't be doing it.

> 
>>>>>>> Well, since the helmet certification standard was established 
>>>>>>> (essentially less than 300gs linear deceleration in a 14 mph 
>>>>>>> impact), it became known that linear deceleration was far less of 
>>>>>>> a problem than rotational acceleration. Twisting the head and 
>>>>>>> brain caused far more brain injury than smacking them. But a 
>>>>>>> helmet protrudes at least an inch from the head, providing a 
>>>>>>> longer lever arm for glancing blows, potentially worsening 
>>>>>>> rotational acceleration. (Note that a bare head's slippery hair 
>>>>>>> and very loose scalp are probably evolutionary tricks to reduce 
>>>>>>> that hazard. The helmet makes those ineffective.)
>>>>>>
>>>>>> a specious argument with no scientific substantiation.
>>>>>
>>>>> What part did you not understand?
>>>>
>>>> I understood all of it. What I'm stating is that you have no data to 
>>>> support the that helmets "provide a longer lever arm and thus can 
>>>> cause more injury" claim. Every study I've link states the exact 
>>>> opposite.
>>>
>>> Well, I suppose the "thus" is not totally proven. I don't see how you 
>>> can claim they do not provide a longer lever arm for glancing blows.
>>
>> I didn't. I wrote that " you have no data to support the that helmets 
>> "provide a longer lever arm and thus can cause more injury" claim. 
>> Every study I've link states the exact opposite."
> 
> I don't see you've linked any studies that specifically address the 
> lever arm! 

And you wont. Who would volunteer as a test subject?

> And I'll note a parallel between your previous objection on a 
> related issue, and my statement:
> 
> You put high value on the word "can" by saying "... They _can_ reduce 
> severity..." to excuse the countless times they do not. Yet you're 
> ignoring my statement where I'll emphasize: "... a longer lever arm and 
> thus CAN cause more injury."

Nope, that's a false equivalence. "can reduce severity" is supported by 
data, 'longer lever arm" is not.

> 
> We're both discussing possibilities, not definite 100% effects, aren't we?

Yup.

> 
> 
>>
>>>  A helmet absolutely is larger than the head. The radius upon which a 
>>> glancing force acts on a helmet is certainly larger than the radius 
>>> on a bare head. And BTW, that means that a certain number of misses 
>>> must be converted to hits. I hope that's obvious to you.
>>
>> In terms of physics it's a logical path, but you have to purposely 
>> ignore that are no studies done which show the added leverage of the 
>> helmet causes more injuries than an beare head,...
> 
> Of course there are no studies on that detailed point. How on earth 
> would such a study be done? By testing a helmet with and without a 
> radius larger than a bare head?

Exactly as I noted above.

> 
>>> In any case, _something_ seems to be causing a correlation between 
>>> rising helmet use and rising cyclist concussions. If it's not the 
>>> factors I speculated on, I'd be interested in hearing your theories.
>>>
>>> See https://www.cbsnews.com/boston/news/i-team-concussions-on-the- 
>>> rise- among-cyclists/
>>>
>>> https://www.slatervecchio.com/blog/bike-helmets-dont-protect-against- 
>>> concussions/
>>>
>>> https://www.cbc.ca/news/health/bike-helmets-should-address- 
>>> concussion- risk-scientists-say-1.1367454
>>>
>>
>> wow...ok, first off, you're again stuck in the past. All three of 
>> those are over 11 years old. 
> 
> It's still the same universe, Zen.

Yup, only this one has tons more data, and deeper analysis with better 
tools. The newer studies (already liked several times) show a blatant 
linkage to helmets providing protection.

> 
> Secondly, you missed one important statistic, as
>> stated in
>> "Traffic-related bike fatalities decreased despite the sharp increase 
>> of cyclists on the road.....Fatalities were down, but brain injuries 
>> were up".
>>
>> More people wearing cycling helmets means less fatal head trauma. The 
>> result is more _non_ fatal head trauma.
> 
> Look at the numbers, please. They're comparing 1997 to 2011 (in the same 
> old universe!).  Wiki says 1997 had 814 bike fatalities. 2011 had 682 
> (one of the lowest counts ever).  That difference of 132 can't possibly 
> be enough to explain this: “Between 1997 and 2011 the number of bike- 
> related concussions suffered annually by American riders increased by 
> 67%, from 9,327 to 15,546” 

tons more data, and deeper analysis with better tools.
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