“Helmet shapes that transform linear shocks into rotational shocks are more dangerous” was literally just one thing I threw in as maybe, part, of the cause of those numbers I had read about in Denmark, which was a single line in a much broader discussion.

(I never actually said that it totally offsets other effects, by the way, I just thought it was a contributing factor for the counter-intuitive results I had read in that study)

You just then grabbed that one “maybe this part of it” line of mine and ran with it as if I was claiming that wearing a helmet doesn’t reduce the risk of head injuries, something I did not and even though I actually wrote three times (including in the post immediately after your first reply) that wearing a helmet does reduce the risk of head injuries.

As for the rest, as I basically said in the last paragraph of the last post, yeah, based on the recent study you linked that shows there is no clear evidence for a risk compensation effect, so as per all evidence wearing helmet when cycling is safer than not because the helmet does protect the head and if there is no risk compensation effect then there is no indirect increase in risk (due to riskier behaviors) from wearing a helmet. What I remember from what I read as per my original post was a tiny effect (something like 2%) so maybe that was within the error margin. I mean, I’m pretty sure I read about it over a decade ago and you linked to a study which is more recent than that.

Common bicycle helmet

Common motorcycle helmet

Are you really telling me that in the horizontal axis the first doesn’t have a far bigger ratio of major-axis to minor-axis than the second?

Statistics show that wearing a helmet reduces chances to severe head and brain injuries.

Never disputed. After all a hat too will “reduce chances to severe head and brain injuries”, though by a tiny amount.

The point was always about how much and if in the typical conditions of city cycling it is enough to offset possible negative effects such as increase risk taking and less careful behavior from drivers around cyclists who are better protected.

It’s about aggregated effects rather than this one specific thing you focused on to the exclusion of everything else. If you focus on one thing alone then “always wear a hat when you cycle” would count as a safety recommendation for cyclists.

Mind you from our discussions I did shift my position to think it’s a good idea in overall to recommend people to wear a helmet when cycling (mainly because of the study you linked that reviewed various papers and found too little indication of a risk compensation effect), though not on mandatory helmet wearing because there the broader implications - as shown by the experience of Australia - are that all in all it causes more deaths because of the indirect effect of people cycling less hence dying in greater numbers because of the higher mortality for people who don’t regularly exercise. There’s also the point I quoted from the Dutch that in terms of policy aiming for second prevention (such as cyclist protection equipment) negatively impacts the investment in primary prevention (i.e. a safer cycling environment).

Ovoid shapes will cause rotational forces on perpendicular impacts, whilst spherical shapes do not. This is just Maths.

Notice how motorcycle helmets are actually spherical.

In my experience the traditional bicycle helmets are half ovoids.

That said I drilled down to the comparative analisys linked from the study you indicated and it basically concludes that people who are more fearful tend to wear helmets when cycling, so the reverse causality relationship of the risk compensation theory (which would be that a person that starts wearing a helmet when cycling becomes more risk taking).

So you make a good point that advising people to wear helmets is not a bad idea.

IMHO, as long as it doesn’t turn people away from a more compreensive risk reduction form of cycling (which is how I personally tackled changing from cycling in The Netherlands to cycling in London, which at the time had much worse cycling infrastructure and were motorists weren’t used to cyclists when I started doing it - by having quite a lot of tricks to keep me safe from the innatention and error of not just motorists but also pedestrians, most of which were not at all needed in The Netherlands were other road users always expect cyclists to be around), it’s fine.

As for mandatory cycling helmets, I’m against it because it severely lowers the uptake of cycling which ultimatelly is worse for people because of worse health outcomes. Also my experience cycling in London during the period were it went from quite atypical to more normalized, is that more cyclists around results in more motorists and pedestrians being naturally aware of and careful towards cyclists (an effect I also noticed from the other side in myself as both a motorist and a pedestrian when I moved from a country with no cycling culture to The Netherlands and got used to lots of cyclists around) which in turn makes cycling safer for everybody - in other words, more cycling adoption makes cycling safer. This seems to be aligned with the most common position in The Netherlands as per my last link:

The Dutch government, private safety organizations and cyclists’ groups all tend to agree on the following propositions: Promoting the use of bicycle helmets runs counter to present government policies that are aimed at the primary prevention of crashes (as opposed to secondary prevention) and at stimulating the use of the bicycle as a general health measure.

Helmet studies typically have a bias for or against from the start.

The reality is wearing a helmet is always safer

You writting one after the other just makes clear you’re hugely biased in this as you basically put forward an absolute statement of yours “wearing a helmet is always safe” as objective truth whilst studies “typically are biased” or in other words, you know better than studies.

Definitelly agree that using numbers from injuries of cyclists with helmets in The Netherlands without any further considerations yields biased results for the reasons you described. It’s not by chance that I did not quote such figures at all and in fact explicitly said from the start that people doing things like speed cycling and mountain biking should wear a helmet.

No idea were you pulled that specific argument you decided to counter in a response to my posts.

Specifically for The Netherlands and from the last link in my previous post, the only thing about them is the general belief there that “Promoting the use of bicycle helmets runs counter to present government policies that are aimed at the primary prevention of crashes (as opposed to secondary prevention) and at stimulating the use of the bicycle as a general health measure” which is really about not having mandatory helmet laws because it reduces cycling in general and how it’s more important to push for safe cycling conditions (such as good cycle paths) than for cyclists wearing protection, all of which makes sense.

Personally I think that wearing a helmet or not should be down to each cyclist and should take in account the conditions they are cycling under, always remembering that wearing a helmet is not a silver bullet. My own experience of cycling in different countries (The Netherlands, England, Germany, Portugal) and different conditions is that the level of risk can be very different sometimes even from city to city, making helmet use more or less important relative to other things.

Again and above all, always keep in mind that wearing a helmet is not going to make you totally or even mostly safe, if only to avoid the increase risk taking due to a sense of increase safety exceeding the actual amount of increased safety from a helmet - as per risk compensation theory - which ultimatelly can make you less safe.

In my view your whole “wearing a helmet is always safer” absolutist posture is a needlessly dangerous mindset to have - it’s far better to have a far more general approach to cycling safety in city traffic (which is basically what I went with when I moved from cycling in the far safer Dutch conditions to cycling in London, meaning that I ran around with all sorts of risk mitigation practices not just towards motorists on the road but even towards pedestrians in the sidewalk that were even adjusted depending in the area of London I was in) that thinking that just a helmet will make you safe.

Sadly I read about this over a decade ago and don’t have a link for it anymore.

I looked around and all I could find were studies pointing out that helmets protect against head injury, which was never in dispute and you yourself linked studies for that - my the point was not about helmets reducing head injuries (though the whole rotational vs linear collisions thing means good helmet design is important) but about how as per risk compensation theory if there is an overal increase in risk due to increased perception of safety it might offset the increased in protection from helmets since helmets only protect the head.

Also found lots of things about how mandatory helmet use for cyclists in overall causes more deaths (for example and another example) because it reduces the number of people who take up cycling and the overall negative health outcomes of fewer people cycling add up to to higher mortality that the increased risk of head injury from cycling without a helmet given the low baseline risk of cycling in general.

Here’s a pretty good summary from the views in the EU.

I’ve actually lived in the place for almost a decade, and the problem there - especially in places like Amsterdam - is much more the tourists stepping into bicycle paths without looking than the actual cyclists.

It actually takes a while to get used to, for example, when crossing a street look twice to each side (and to look properly rather than just slight head turn and rely on sound and peripheral vision to notice approaching vehicles) when crossing a street and also on the other side consider that a car that stopped to let you pass might be hiding a bicycle from your angle.

We used to joke that the proof for us immigrants that one had become a proper Amsterdammer was passing the tourists on the cycle path and just naturally swear at them with “God verdomme” (God damn it).

I vaguelly remember a study in Denmark (which has roughly 50/50 of people cycling with and without helmets) that showed that cyclists who wear helmets were more likely to have serious accidents than those who did not, though by a small percentage.

There are several factors that are believed to be behind such an unexpected statistic:

• Drivers actually act more dangerously around cyclists who seem better protected than around those who do not and the cyclists themselves are more reckless when they feel they’re better protected (the latter being a much broader and well known phenomenon)
• The weight of the helmet, even though it’s quite low, will on a high speed collision pull the head more towards colliding with something than otherwise - in other words, if you fall the helmet actually unbalances your head and makes it more likely your head will hit the ground.
• The human brain is much more resilient to linear shock than rotational shock - basically when something makes your head rotate the brain inside will also rotate though not instantly since it not part of the bone of your cranium, so it will instead get pulled to rotate and similarly when the head stops be pulled to stop rotating, all of which can cause tearing which can kill a person. Cycling helmets tend to make the head rotate on a collision.
• Cycling helmets are only rated to protect from collisions up to (if I remember it correctly) 15km/h
• Cycling helmets do not protect anything else than the head (which links back to the first point)

Anyways, the point being that at the kind of speed and the environment that people cycle in when just commuting in a city, bicyle helmets can actually make it slightly more dangerous.

Mind you, this doesn’t at all mean that in different situations - such as mountain biking or speed cycling - helmets aren’t a must.

In places like The Netherlands pretty much nobody uses a helmet when just cycling in the city.

AI isn’t at all reliable.

Worse, it has a uniform distribution of failures in the domain of seriousness of consequences - i.e. it’s just as likely to make small mistakes with miniscule consequences as major mistakes with deadly consequences - which is worse than even the most junior of professionals.

(This is why, for example, an LLM can advise a person with suicidal ideas to kill themselves)

Then on top of this, it will simply not learn: if it makes a major deadly mistake today and you try to correct it, it’s just as likely to make a major deadly mistake tomorrow as it would be if you didn’t try to correct it. Even if you have access to actually adjust the model itself, correcting one kind of mistake just moves the problem around and is akin to trying to stop the tide on a beach with a sand wall - the only way to succeed is to have a sand wall for the whole beach, by which point it’s in practice not a beach anymore.

You can compensate for this by having human oversight on the AI, but at that point you’re just back to having to pay humans for the work being done, so now instead of having to the cost of a human to do the work, you have the cost of the AI to do the work + the cost of the human to check the work of the AI and the human has to check the entirety of the work just to make sure since problems can pop-up anywere, take and form and, worse, unlike a human the AI work is not consistent so errors are unpredictable, plus the AI will never improve and it will never include the kinds of improvements that humans doing the same work will over time discover in order to make later work or other elements of the work be easier to do (i.e. how increase experience means you learn to do little things to make your work and even the work of others easier).

This seriously limits the use of AI to things were the consequences of failure can never be very bad (and if you also include businesses, “not very bad” includes things like “not significantly damage client relations” which is much broader than merely “not be life threathening”, which is why, for example, Lawyers using AI to produce legal documents are getting into trouble as the AI quotes made up precedents), so mostly entertainment and situations were the AI alerts humans for a potential situation found within a massive dataset and if the AI fails to spot it, it’s alright and if the AI incorrectly spots something that isn’t there the subsequent human validation can dismiss it as a false positive (so for example, face recognition in video streams for the purpose of general surveillance, were humans watching those video streams are just or more likely to miss it and an AI alert just results in a human checking it, or scientific research were one tries to find unknown relations in massive datasets)

So AI is a nice new technological tool in a big toolbox, not a technological and business revolution justifying the stock market valuations around it, investment money sunk into it or the huge amount of resources (such as electricity) used by it.

Specifically for Microsoft, there doesn’t really seem to be any area were MS’ core business value for customers gains from adding AI, in which case this “AI everywhere” strategy in Microsoft is an incredibly shit business choice that just burns money and damages brand value.