[JohnGB]

The Netherlands did a study on bike helmets and found that cars tend to be more dangerous with cyclists if the cyclists are wearing a helmet, which is why there are no mandatory bicycle helmet laws in the Netherlands. However, it's worth noting that the cycling infrastructure in the Netherlands also for the most part separates bikes and cars with more than just a line of paint, so their experience may not translate well to other countries with poor cycling infrastructure.

[float4]

> The Netherlands did a study on bike helmets

This was a British study

> and found that cars tend to be more dangerous with cyclists if the cyclists are wearing a helmet

Re-analysis showed that there actually was no significant effect. Source: https://swov.nl/en/fact-sheet/bicycle-helmets (under: "Do bicycle helmets also have adverse effects?")

> which is why there are no mandatory bicycle helmet laws in the Netherlands

We (the Netherlands) don't have helmet laws because we hate helmets, not because we did research and concluded they'd have significant adverse effects.

[tremon]

because we hate helmets, not because we did research

Actually, we did. From [0] (the link to the study itself is on that page too):

> A recent Dutch study (2021) concludes that many people expect to make fewer bike rides when mandatory helmet laws are introduced. These findings suggest that such a law would have a negative effect both on bike usage and on public health in general.

In addition to the standard arguments already posted here about safety in numbers, efficacy of a helmet, and infrastructure design, they also mention a few practical problems with helmets:

- What to do with the helmet when you're not wearing it? A good helmet is too big to just store in a coat pocket or a handbag.

- What to do if you lose your helmet or it gets stolen? How will you make it home then?

[0] https://www.fietsersbond.nl/de-fiets/accessoires/fietshelmen...

[Fogest]

I experience the same delema's when I ride a motorcycle and have to lug around an even bigger/heavier/more expensive helmet. I sometimes will opt for a car over motorcycle simply because of the PPE element. However, my solution to that problem is not to skip wearing my PPE. I am not sure it should be the same for cycling either. In places like the Netherlands I guess it can make more sense for PPE to not have as much importance as you're going to have far less risk of an head injury compared to a rider in many North American cities.

[lmm]

The "re-analysis" just does a bunch of ad-hoc adjustments to make the study underpowered. You could make literally any scientific paper show no effect by doing the same thing.

[ndsipa_pomu]

I believe that re-analysis was refuted by Dr Ian Walker: https://psyarxiv.com/nxw2k

[moffkalast]

> because we hate helmets

I mean yeah helmets for commuting at a snail's pace in areas without cars are an annoyance at best.

[dylan604]

> and found that cars tend to be more dangerous with cyclists if the cyclists are wearing a helmet

I know that when I'm driving a car, I specifically behave differently when I see a bicyclist with a helmet vs without. /s

This just sounds so preposterous. First off, I doubt the average driver notices bicyclists at all. Of those that do, I'd seriously doubt if they even consider that they are wearing a helmet or not and just express frustration at the bicycle being there in the first place. The suggestion that a driver notices a helmet and acts more aggressively towards the rider or that they give a wider berth to the rider when not wearing a helmet is just "trying too hard" for lack of better words to describe my incredulity.

[paddez]

> I doubt the average driver notices bicyclists at all.

This seems like an issue. The average driver should absolutely notice the environment they're operating in.

This includes noticing those around them. This should be especially true for the more vulnerable road users.

[dylan604]

Um, that's the point of it being THE issue.

If you are riding a bicycle in an area (like mine) where biking is just not at all that common in the majority of areas, then the drivers of motor vehicles are just out of practice of noticing bicycles. It is not in their muscle memory of needing to look out for them. Other cars, sure. Pedestrians, maybe (but that's probably pretty low as well).

[kenjackson]

I do behave differently with some bicyclists than others and it might be correlated with helmet use.

If I see a bicyclist that looks like a bicyclist I tend to drive closer to them because I expect they are going to stay in their lane. Conversely, people who look like they aren't regular bike riders or teenagers just screwing around -- I will give a much wider berth... in some cases even going a completely different route to avoid them.

[lcnPylGDnU4H9OF]

> If I see a bicyclist that looks like a bicyclist

I recall a coworker explaining the duality of cycling in full kit vs. cycling in "street" clothes with his children. In the former case, he appears as a pro or semi-pro cyclist and in the latter, as a dad spending time with his children.

It's not hard to guess which get-up gets him honked at, coal rolled[0], etc. It's also not hard speculate that a driver is more likely to give the dad spending time with his children more room on the road. (Of course, in either case the cyclists should all be wearing helmets, but we're only even having this discussion because not all are so responsible.)

[0] https://en.wikipedia.org/wiki/Rolling_coal

[Quillbert182]

Yeah, I know someone who has no issue seeing people biking who look like they are going somewhere, but he absolutely hates people who look like they are biking for exercise. His logic is that roads are built for transportation, and people shouldn’t be blocking parts of the road to get a workout in.

[Fiahil]

that study comes out a lot, but, AFAIK was poorly challenged. It would be nice to get a second opinion on this topic before jumping to conclusions.

[lukas099]

It may not be perfect, but if it's the best study we have on the matter I think we should tentatively and judiciously accept it.

[cryptonector]

Why not attempt to reproduce it?

[lukas099]

We should attempt to reproduce it, but that will take time and until that happens, we should go with the best information we have.

[snakeboy]

I would assume there is quite a lot of evidence for the efficacy of helmets in the event of a crash, no? I think in general it makes more sense to give credence to studies that give intuitive results that are explainable by sound first principles modeling, rather than one study that gives an unintuitive result based on human behavior.

[ThatGeoGuy]

Not really? There may be slight reductions in some injuries as a result of helmet use, but for most cyclists this isn't really what you'd call definitive data. At the end of the day, a few inches of foam isn't going to protect you from a few tonnes of steel.

That said, it's notoriously under-studied. If you look into "best helmet" in terms of safety you'll see a lot of marketing speak and not a lot of science. The way that helmets are tested tend to 1) not be reflective of actual use of the helmet in a conflict scenario and 2) tend to make pretty broad assumptions about the largest danger factor on the roads.

The thing is that you would /think/ that there's a lot of evidence out there for helmet use. The most compelling evidence for helmet use is for drivers in cars / automobiles, and we wouldn't dare mandate that into existence.

Helmet laws always seem to get people ruffled up but at the end of the day the number of bike fatalities is already low, and skewing that in terms of helmet use somewhat misses the point - dedicated and separated bicycle infrastructure will have a vastly larger impact compared to any mandate on using a helmet. It seems like arguing about adding a mandate on helmets is just an easy way for the system to wash its hands of responsibility for not regulating vehicle and street design more thoroughly.

[peoplefromibiza]

> Not really? There may be slight reductions in some injuries as a result of helmet use,

Yes, actually, really!

Helmets provide a 63 to 88% reduction in the risk of head, brain and severe brain injury for all ages of bicyclists

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7025438/

There was a significantly higher crude 30-day mortality in un-helmeted cyclists 5.6% (4.8%–6.6%) versus helmeted cyclists 1.8% (1.4%–2.2%) (p<0.001). Cycle helmet use was also associated with a reduction in severe traumatic brain injury (TBI) 19.1% (780, 18.0%–20.4%) versus 47.6% (1211, 45.6%–49.5%) (p<0.001), intensive care unit requirement 19.6% (797, 18.4%–20.8%) versus 27.1% (691, 25.4%–28.9%) (p<0.001) and neurosurgical intervention 2.5% (103, 2.1%–3.1%) versus 8.5% (217, 7.5%–9.7%) (p<0.001).

https://bmjopen.bmj.com/content/9/9/e027845

“The evidence is clear: helmets save lives and significantly reduce the risks of severe injury,” said Lois K. Lee, MD, MPH, FAAP, lead author of the statement, written by the AAP Council on Injury, Violence, and Poison Prevention. “And yet sports-related injuries make up a substantial proportion of all traumatic brain injuries. As a pediatric emergency medicine physician, I advise all my patients – and their parents-- to wear helmets.”

https://www.aap.org/en/news-room/news-releases/aap/2022/amer...

[ThatGeoGuy]

I don't think I'm necessarily disagreeing that in the worst-case scenario that helmets do the job of reducing brain and skull trauma. Doing something is the alternative to doing nothing, you'd expect some difference here.

My problem is that helmet use isn't exactly "well-studied." All these studies look at existing reports from medical centres on injuries & deaths. This doesn't actually account for the broader behavioural changes in the system, or look at causes outside of "injured while wearing a helmet vs. not."

In any other industry this kind of reporting (while factual) is absolutely ignoring everything else. A short list of what isn't being considered:

- Which road and behaviour led to incident?

- Which kinds of road conflicts can be addressed by helmets?

- How did road design lead to the incident?

- Were environmental factors a concern (winter, ice, rain, etc.)?

- How does behaviour for the cyclist change as a result of not wearing a helmet?

- How does behaviour for other road users change as a result of a cyclist not wearing a helmet?

- What kinds of helmets are more viable for protection in the case of the most extreme (and most common) conflict scenarios? How do we then test these helmets to ensure compliance in manufacturing?

These are all questions you'd expect to be answered here, and then you'd do the cost-benefit analysis on whether a mandate is necessary or not. A "well-studied" field would have discussed these effects in broader detail, not just short-cut to "fewer people who already had huge injuries while cycling died when using a helmet." That is not the entire problem, because it leaves out a huge sampling of people who do not wear helmets and do not make it to the hospital in the first place.

[seadan83]

The kicker is rate of head injuries during a bicycle crash. A fraction of crashes involve a person's head (though when it does, for those one in ten falls, you really want it)

The numbers are under reported. Every cyclist I know that uses a bike for transport has been hit by a car. Myself thrice, never reported. Crashes involving myself, never reported. Hence, there is a bias in the data for the really traumatic injuries

[ndsipa_pomu]

There's some debunking of helmet studies here: https://www.cyclehelmets.org/1027.html

[banannaise]

Bicycle helmets are designed to protect riders from collisions with terrain at normal cycling speeds (in fact, less than that; helmet tests are done with a speed of about 14 miles per hour [0]).

Cyclists who are hit by traffic are likely to be hit much, much harder than that. Therefore the effect of the helmet is more or less entirely untested, and manufacturers have no incentive to design helmets for that scenario.

[0] https://helmets.org/limits.htm

[lukas099]

I intentionally said IF it's the best research we should listen to it. I'm agnostic on whether or not it is the best research.

[cryptonector]

I got to witness an accident where a helmet would have made a huge difference for the cyclist. A lady was cycling at fairly low speed on a street that had old rails, then her front wheel apparently got stuck in a rail and she fell over and got a pretty serious looking head injury. Several of us in cars pulled over, called 911, and waited till the ambulance arrived and told them what happened. I have no idea what happened to her in the end, but she was unconscious and bleeding profusely from her her. She was not wearing a helmet, as you might surmise.

[peoplefromibiza]

> The Netherlands did a study on bike helmets

They did not.

But it's true that "Dutch neurologists and surgeons call on people to wear helmets while cycling"

https://road.cc/content/news/dutch-neurologists-call-cyclist...

Because, you know, politicians would do anything to keep people voting for them, including putting people lives at risk to please them (COVID just proved it, if there was some doubt left), but doctors opinions are a bit more of a reliable source to understand what could potentially kill you and what could save your life.

[kqr]

I don't agree. A surgeon is not going to see the vast majority of people who don't suffer head trauma, so they are not any more reliable than anyone else. If anything, they are likely to be more biased than the average person.

Now, get me a statistician and we can talk.

[peoplefromibiza]

> A surgeon is not going to see the vast majority of people who don't suffer head trauma

Which is a very silly argument.

A surgeon is one among the few that can see a spike in brain traumas cases and can investigate the causes, it's totally more reliable than you or me, because he has the data and the knowledge, we don't.

I don't know about you, but I would ask a veteran about the horrors of war, not to 4 years kids, who, having seen none of it, are, by your reasoning, less biased.

> A surgeon is not going to see the vast majority of people who don't suffer head trauma

Because surgeons are notoriously not people too and live in a closet in the hospital.

> Now, get me a statistician and we can talk.

first of all, medical professionals typically study statistics, epidemiology doesn't really figure out itself on its own.

Secondly, I work with statisticians to assess the risks for insurance companies (not in the US). I work with that kind of data everyday and, guess what, MDs reports are highly predictive of risks, the average Joe with a laptop opinions, are discarded because, after examination, have been found "completely non-predictive".

[mmcnl]

Ban cycling. Even less trauma. And why stop there, make it illegal to walk outside as well. No more pedestrians getting hit by cars!

This sounds absurd ofcourse, and it is. But from the point of the surgeons it is not absurd, as it reduces trauma significantly. So any decisions should be taken by taking into account socio-economic effects as well. Cycling is a part of Dutch culture and compared to other countries we are doing very well. Mandatory helmets are a big deal (where do you keep the helmets?) and will definitely move people from bikes to cars.

[xapata]

> medical professionals typically study statistics, epidemiology doesn't really figure out itself on its own.

Having tutored medical professionals trying to pass their epidemiology classes, I would not make that claim. From my observations, epidemiology and statistical literacy is treated as a "check this box" effort, the least important of their courses.