Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

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I'm afraid your helmets failed.

I don't think you understand how helmets work.
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I came to post the articles. That's all.

http://www.cyclehelmets.org/1209.html

As stated prior to deleting my medical history-
Both times there was significant compression.
Additionally- congratulations- that is a fantastically biased site.

You said the helmets were split. That means they failed.

Having read through that site- I take it in the same vein as the opinions of this thread (and again- how people should take my own)- examine the data and form your conclusion.
Outdated (last update was 2012) and substantially biased.

It took 1/1000th of a second for your helmets to split. After that, where do you think the force went? That's not how helmets work, a split means the integrity's compromised. Your helmets failed.

WRT to helmet design- There is only so much force a compressive structure such as the foam can take. After that point - if there is remnant force- it will be transmitted to a) the helmet and cause a split, or b) your head.
There is a limited amount of foam that people are willing to wear, and since my helmets both showed substantial compression, I'm pretty sure they worked as much can be expected.
Anecdotally- the injuries were less severe. (this is not data and importantly why I've repeatedly stated it as such).

If your helmet split it means it failed. That's not how they work. What make of helmets were they?

How about Cycling UK for references? https://www.cyclinguk.org/sites/default/files/document/2017/11/helmets-evidence_brf.pdf

I think not many people will argue with you that helmets reduce head injuries (unless they aren't put on properly). However, I think you're missing the bigger picture that mandating helmet use (or even strongly encouraging use) can lead to less people cycling. There are studies in the pdf on exactly this happening in Aus and NZ

Perhaps its my fault for engaging with you, or not making things clear enough.
Either way we've now diluted the thread. So I refer people to the literature again:
There is statistically good evidence that helmets reduce risk:
-https://www.ncbi.nlm.nih.gov/pubmed/2745­0862

There is good evidence that in laboratory tests there is a reduction of instrument based replication of head injury in bike accidents:
https://www.ncbi.nlm.nih.gov/pubmed/2468­6160

There is limited evidence supporting reduction in cycling admissions following helmet legislation:
Against:
https://www.ncbi.nlm.nih.gov/pubmed/2367­4137
For:
https://www.ncbi.nlm.nih.gov/pubmed/2657­7650

Here's the study from mary's:
https://www.ncbi.nlm.nih.gov/pubmed/2894­5822
Here's a study from Taiwan with 'insignificant' increased hospitalisation for non-helmeted cyclists (I think)
https://www.ncbi.nlm.nih.gov/pubmed/2934­2208
Here's one showing reduction in facial trauma:
https://www.ncbi.nlm.nih.gov/pubmed/2875­1943
And here's one from Korea: " A lack of helmet use was significantly associated with serious outcomes"
https://www.ncbi.nlm.nih.gov/pubmed/2870­4554

Since I am not a helmet designer- and (I suspect based on the evidence provided) neither are you, the best we can come up with is second hand information garnered from equally polarised sites and conjecture- I really don't have any desire to continue.

It is easy to forget that bicycle helmets are only designed to protect
in minor impacts:

“In cases of high impact, such as most crashes that involve a motor
vehicle, the initial forces absorbed by a cycle helmet before breaking
are only a small part of the total force and the protection provided
by a helmet is likely to be minimal in this context. In cases where
serious injury is likely, the impact energy potentials are commonly of
a level that would overwhelm even Grand Prix motor racing helmets.
Cycle helmets provide best protection in situations involving simple,
low-speed falls with no other party involved. They are unlikely to
offer adequate protection in life-threatening situations.“

Dr Carwyn Hooper from St George’s University in London reports:

“Looking at evidence, it does not matter if people are wearing a
helmet or not, any serious accident on a bike is likely to kill them”

Helmets increase the volume of the head, thus the chance of the head
hitting the ground in an accident. Helmets also increase the risk of
neck injuries, and can aggravate brain injuries. There is no guarantee
that a fall with a helmet will result in less severe head, neck or
brain injuries.

It is natural to assume a helmet saved us. But that doesn’t mean it is
true. We don’t know what would have happened without it. Cyclists,
with and without helmets, get hit by cars; the survival rates are
identical. Most bicycle accidents do not result in serious head
injuries, with or without helmets. We tend to overlook this, and
attribute a lack of head injury to the helmet:

https://crag.asn.au/the-fallacy-of-the-cracked-helmet/

Thanks- good data for me to read up

I'm done.

If your helmet split it means it failed. That's not how they work.

That isn't what the link you posted says. The last line is:

'disregard the breakages and look to see if what's left of the styrofoam has compressed. If it hasn't, you can be reasonably sure that it hasn't saved anyone's life.'

It's pretty common, people claim a helmet saved their life and it turns out their helmet failed.

There's also the curious confidence of helmet wearers boasting about the crashes they keep having...

It's pretty common, people claim a helmet saved their life and it turns out their helmet failed.

Again, that's not necessarily what that link says. It only says it failed if the styrofoam didn't compress. Any data on that? Not many people are checking to see if the styrofoam has compressed during an impact, regardless of whether helmet has cracked or not. Of course, any claim that a helmet's performance has been life saving is likely to be speculative...

If the styrofoam is compressed, it still doesn't prove that a helmet
had a protective effect. This can be demonstrated with a fist and a
brick wall.

If you 'shadow box' at the wall but carefully stop your fist about 50
mm before it reaches the wall (be sure it's limited by your arm's
length), no harm will come to your fist. If, without changing your
position, you slip a 75 mm thick piece of styrofoam against the wall
and repeat the punch, you'll get compressed (and cracked) styrofoam
and false 'evidence' that it saved you from harm. In other words, many
impacts of helmets would be near misses with bare heads.

In high impact crashes, such as most that involve motor vehicles or
fixed objects like concrete barriers and lamp posts, the forces can be
so great that a helmet will compress and break in around 1/1000th of a
second. The absorption of the initial forces during this very short
period of time is unlikely to make a sufficient difference to the
likelihood of serious injury or death. It is for this reason that
helmets contain stickers noting that no helmet can prevent all head
injuries.

Ibid.

• that is a fantastically biased site.
  

It's one of the few sites that just posts research without coming down on any side. The best neutral reference site on helmets.

Though if your views aren't neutral the site will seem fantastically biased

If you 'shadow box' at the wall but carefully stop your fist about 50 mm before it reaches the wall (be sure it's limited by your arm's length), no harm will come to your fist. If, without changing your position, you slip a 75 mm thick piece of styrofoam against the wall and repeat the punch, you'll get compressed (and cracked) styrofoam and false 'evidence' that it saved you from harm. In other words, many impacts of helmets would be near misses with bare heads.

Lol wtf

helmets make your head area bigger cos they go on the outside.

I fell off my bike when I was really pissed and wasn't wearing a helmet.

My head shadow boxing must have been about off that night because I ended up in hospital.

I think that a helmet may have protected my fizzog from the trauma

My mate wore a helmet and he died.

There is statistically good evidence

To the extent that the evidence is any good (and I'm not coming down on either side of that question), it might lead to well informed people deciding to wear a helmet voluntarily. That is nothing to do with the legal compulsion question, which aside from the points introduced earlier about dissuading cycling and thereby causing more harm than good to population health, has a much more serious and for my money insurmountable problem; for all legal prohibitions, at the margin, the state must be prepared to kill citizens to enforce them. If you're going to start killing people for resisting your laws, you need to be absolutely confident that the public goods you are buying with those deaths are worth the price. There's no way even the most charitable reading of the possible benefit of making everybody who doesn't already voluntarily wear a helmet wear one under penalty of law amounts to a justification for killing people.