Re: Helmet efficacy test

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:

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Trouble is, the protection from a bike helmet is far, far less than people are led to believe. Look up the standardization test.

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"led to believe" by what metric? I've never seen any literature claiming a helmet _prevents_ serious head trauma.

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WHAT???

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No helmet manufacturer or helmet advocacy group claims helmets _prevent_ serious head trauma. They _can_ reduce severity, not prevent it.

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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.
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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."
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?"

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.)

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a specious argument with no scientific substantiation.

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What part did you not understand?

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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.

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

 

 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?

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.
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See https://www.cbsnews.com/boston/news/i-team-concussions-on-the- rise- among-cyclists/
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https://www.slatervecchio.com/blog/bike-helmets-dont-protect-against- concussions/
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https://www.cbc.ca/news/health/bike-helmets-should-address-concussion- risk-scientists-say-1.1367454
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 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.
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”  You've got at least 6000 concussions you haven't explained.
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- Frank Krygowski