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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Helmet efficacy test
Date: Wed, 26 Mar 2025 17:53:25 -0500
Organization: Yellow Jersey, Ltd.
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On 3/26/2025 3:49 PM, Zen Cycle wrote:
> 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 
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