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From: Zen Cycle <funkmaster@hotmail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: RE: Re: Helmet efficacy test
Date: Wed, 26 Mar 2025 16:49:02 -0400
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On 3/26/2025 4:25 PM, cyclintom wrote:
> On Wed Mar 26 15:57:28 2025 Zen Cycle  wrote:
>> On 3/26/2025 11:47 AM, Frank Krygowski wrote:
>>> On 3/26/2025 10:16 AM, Zen Cycle wrote:
>>>> On 3/25/2025 10:24 PM, Frank Krygowski wrote:
>>>>> On 3/25/2025 5:02 PM, cyclintom wrote:
>>>>>>
>>>>>> How would you propose that a helmet cause a head injury? You could
>>>>>> argue that the foam helmets are heavy and might increase your
>>>>>> chances of hitting your head but the Wavecel helmets are light.
>>>>>> Helmets don't interfere with vision on a normal road bike.
>>>>>
>>>>> There's data out there indicating that people wearing helmets do
>>>>> crash more (and show up in ER more) than people without helmets.
>>>>
>>>> Irrelevant, even if it were true. Statistical analysis on injuries
>>>> with vs sans helmets take that into account.
>>>
>>> Nope. Here's why:
>>>
>>> The typical "case-control" study design - that is, counting head
>>> injuries (usually) or brain injuries in those presenting to ER, is built
>>> on the assumption that the sample presenting to ER is representative of
>>> the cylcling population as a whole. There's a significant amount of data
>>> showing that's not the case. Specifically, people wearing helmets
>>> present to ER more than the general cycling population.
>>
>> I've already presented several studies that show more parity. You've
>> been reading old literature.
>>
>>>
>>> The easiest example to find is the 1989 Thompson & Rivara paper.
>>
>> Yup, a 35 year old paper....that's currently valid alright, no one has
>> done any substantive work in the area in the last 35 years...<eyeroll>
>>
>>> That
>>> team of doctors was all in on helmet promotion before they published
>>> their "case-control" study claiming 85% protection. They had just
>>> completed street surveys of the study area that found ~3% of cyclists
>>> were wearing helmets. But the cyclists presenting to ER had 21% wearing
>>> helmets. IOW, a person wearing a helmet was seven times more likely to
>>> show up in ER.
>>>
>>> Why would that be? There are various possibilities. One might be that
>>> the most nervous people would be the first to cave in to helmet fear
>>> mongering, and when they felt a head bump they thought "Omigosh, I might
>>> die!" and went to ER just to be sure. Another might be that helmeted
>>> people might suffer more head (or really, helmet) strikes with the
>>> ground just because the helmet is bigger than the head. (Evolution, like
>>> of reflexes and neck muscles, etc. tends to be efficient, i.e. nothing
>>> extra.) It might be that the people in helmets had better insurance
>>> coverage and didn't fear ER expense.
>>
>> In 1989, that was likely the case.
>>
>>>
>>> There were other differences between the "cases" and "controls," as well
>>> as between both groups and the general population - as explained here:
>>> https://www.cyclehelmets.org/1131.html and that is generally the case.
>>> Another study by a Dr. Crocker of Austin, TX was performed specifically
>>> to promote the idea of an all-ages mandatory helmet law (MHL). Crocker's
>>> study failed to find significant benefit from helmets, largely because
>>> he included a confounding factor almost always missed: Alchohol
>>> consumption. He found that drinking then riding significantly increased
>>> risk of brain injury, but riding sober without a helmet did not have
>>> significantly more risk than riding with a helmet. This is important,
>>> because (almost?) all other pro-helmet studies have not recorded blood
>>> alcohol content, and there's no way to retroactively know which of the
>>> injured no-helmet folks were tipsy.
>>
>> Again, try to keep current:
>> https://pmc.ncbi.nlm.nih.gov/articles/PMC6747631/
>>
>> "There was an association between alcohol intoxication and the failure
>> to wear a cycle helmet (p<0.001). However, there was no correlation
>> between crude mortality and alcohol consumption (3.5%?vs 3.2% NS); this
>> was true for those wearing a helmet (2.4% vs 1.8%) at the point of
>> injury and those not (6% vs 3.8%)"
>>
>>>
>>>
>>>>
>>>> (No, it's not
>>>>> because those without helmets didn't survive, as some have claimed.)
>>>>>
>>>>> While not a direct mechanical cause if injuries, some studies - and
>>>>> many, many posted discussion remarks - indicate that people wearing
>>>>> helmets are indulging in "risk compensation" meaning "Hey, I'm
>>>>> wearing a helmet do I can take more risks." (I did that today, but
>>>>> I'll probably wait until tomorrow to post about it.) We've had people
>>>>> post here that they would never do the risky mountain biking they do
>>>>> without the helmet. We've had people say "I would never ride that
>>>>> busy road without a helmet."
>>>>>
>>>>> Risk compensation is probably near-universal with lots of "safety"
>>>>> devices. It's not inappropriate as long as the increase in risk is
>>>>> commesurate with the increase in protection.
>>>>
>>>> Again irrelevant. The Moral Hazard argument has a place, but it isn't
>>>> in the discussion of whether helmets are protective or not.
>>>
>>> If you're restricting discussion to mechanical effectiveness, you're
>>> correct.
>>
>> Thank you
>>
>>> If you're allowing discussion on overall reduction in brain
>>> injury due to widespread helmet use, you're wrong. If a person takes
>>> additional risks because of overestimating his invulnerability, he's
>>> likely to pay for the indiscretion. And almost all helmet promotion is
>>> intended to trigger widespread use in hopes of reducing total injury
>>> rates or counts.
>>
>> And it does, even with "risk adjusted" studies. From the above study:
>> "There was an increased crude 30-day mortality in the group not wearing
>> a cycle helmet 5.6% (4.8%?6.6%) versus helmeted cyclists 1.8%
>> (1.4%?2.2%) (p<0.001); corresponding risk adjusted excess survival rates
>> (W scores)22 were 1.1 (?0.1 to 2.2) and 2.4 (1.3?3.6), respectively."
>>
>>>>> 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.
>>
>>>
>>>>> Oh, and about helmets mechanically causing injury? Curiosity about
>>>>> that surged once it became clear that helmeted cyclists seemed to be
>>>>> over represented in concussion counts.
>>>>>
>>>>> 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.
> 
> For what reason would Thompson and Rivera have their work double checked? 

The Thompson and Rivera study covered 235 riders from one year of data 
and only 7% wore helmets.  The Dodds et al study 
(https://pmc.ncbi.nlm.nih.gov/articles/PMC6747631/) reviewed data on 
6621 ER patients over 5 years of which 65% were wearing helmets.

Medicine was different back then, Access to data, the kind of data, 
treatment methods all have changed since 1989.

> They haven't run any modern tests of Penisilin either. 

https://pubmed.ncbi.nlm.nih.gov/?term=penicillin&filter=datesearch.y_1

Within the past year there have been over 2500 white papers on 
penicillin research.
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