Helmets - the definitive thread.. Mod Note - Please read Opening Post

Iwannahurl · 17-02-2014 9:29pm

Capt'n Midnight wrote: »

It's because the solvents used in the glue for the sticker might weaken the plastic used in the helmet.

That applies to all helmets including those designed to offer protection in a road traffic accident as well as cycling helmets.

I thought the plastic was just a decorative skin. What are its intrinsic protective properties?

With regard to other substances, such as "body fluids", causing damage, I remember a motorcyclist (unfortunately deceased) whose cat p:ssed in his helmet. He had no choice but to wear it, and to add insult to injury it was a male cat so the hormonal content was particularly rank.

doozerie · 17-02-2014 9:43pm

Iwannahurl wrote: »

I thought the plastic was just a decorative skin. What are its intrinsic protective properties?

If I remember some of the blurb correctly, the plastic shell helps to hold the helmet together on impact while the polystyrene supposedly does the job of absorbing the force of the impact.

Iwannahurl · 17-02-2014 10:45pm

Sort of like a crumple zone, perhaps?

doozerie · 17-02-2014 10:51pm

Iwannahurl wrote: »

Sort of like a crumple zone, perhaps?

The shell? The shell itself doesn't crumple, it just keeps the potential fragments of polystyrene together. So a bit like sellotape on broken pottery. Or tits on a bull. Depending on your view on the efficacy of helmets.

tomasrojo · 18-02-2014 9:06am

buffalo wrote: »

http://road.cc/content/news/111258-chris-boardman-helmets-not-even-top-10-things-keep-cycling-safe

I concur. </Carl>

Chris Boardman does not yearn for the quiet life, does he? He'll be inundated after this. Very ambitious, trying to move the debate on. Be very nice if it suceeded.

CramCycle · 18-02-2014 9:12am

tomasrojo wrote: »

Chris Boardman does not yearn for the quiet life, does he? He'll be inundated after this. Very ambitious, trying to move the debate on. Be very nice if it suceeded.

https://www.youtube.com/watch?v=SyQ-0JOF1Qk

It was between this and Martin Luther King's "I Have a Dream" speech

doozerie · 18-02-2014 10:55am

tomasrojo wrote: »

Chris Boardman does not yearn for the quiet life, does he? He'll be inundated after this. Very ambitious, trying to move the debate on. Be very nice if it suceeded.

I agree. He has been vocal in other (cycling) areas too, and hopefully he'll have a positive impact there too.

Chips Lovell · 18-02-2014 11:11am

Chris Boardman wrote:

Evidence and statistics were bypassed in favour of opinions and anecdotes on sideline topics.

It's not just MPs who are guilty of this. It's endemic in almost every debate about cycling safety, even among cyclists.

monument · 13-03-2014 5:18pm

This is from the latest 'a helmet saved my life threads (aka the sheep thread)...

NBar wrote: »

Lucky lucky, speedy recovery...was having this discussion earlier today to a teenager who didn't want to wear his bike helmet, needeless to say the bike went back into the garage, no lid no cycle

Fairly clear (and a sad) example of helmets stopping people from cycling and how teenagers will pick no cycling over having to wear a helmet.

Chips Lovell · 06-05-2014 9:14am

CramCycle · 06-05-2014 9:19am

Vladimir Kurtains wrote: »

PIC

Disapproving look from a guy with no brakes on his bike :pac:

Cabaal · 06-05-2014 10:19am

monument wrote: »

Fairly clear (and a sad) example of helmets stopping people from cycling and how teenagers will pick no cycling over having to wear a helmet.

Its ok, he'll play console games instead and prefer to stay inside doing that instead of being outside in the fresh air.

Sure its not like obesity etc is a big deal :eek:

tomasrojo · 06-05-2014 1:55pm

Bikesnobnyc linked to this:
http://www.slate.com/articles/double_x/the_kids/2014/05/helmets_for_kids_they_won_t_protect_your_children_from_concussions_and_other.html

Quite good addition to growing media attention on helmet use among minors and the failure to address concussion. Some stuff about rotational acceleration and diffuse axonal injuries. Doesn't mention the theory that some helmets make rotational acceleration worse.

(Also contains a claim that sports helmets "definitely" save lives, by preventing skull fractures, which, while it's a common claim, I've yet to see strong statistical evidence of. Possibly because skull fractures aren't a common cause of death? I read that somewhere, but I don't have a citation. Also, claims in article about sports helmets addressing "high impact" linear accelerations seems exaggerated for bicycle helmets, given the standard 20km/h drop test.)

Inquitus · 06-05-2014 2:01pm

I crashed recently and the helmet took the impact and defo saved me from worse had it been my skull in contact with Stamullen's finest tarmac.

AstraMonti · 06-05-2014 2:04pm

The helmet is twice the size of your head though so it will be impacted in places your head wouldn't.

Inquitus · 06-05-2014 2:06pm

AstraMonti wrote: »

The helmet is twice the size of your head though so it will be impacted in places your head wouldn't.

I hit the ground head first, it definitely prevented my head having direct contact with the road, imho that was a good thing.

tomasrojo · 06-05-2014 2:11pm

I'm really talking about statistical evidence based on large numbers of people collected methodically. Such as "death rate due to head injuries goes down as helmet wearing ges up". That would adequately meet the requirement for saying, as the Salate journalist did for sports helmets, that helmets definitely save lives.

It seems probable that they ameliorate some injuries, and your fall might very well fall into that catehory, but it's not quite what I'm talking about.

Capt'n Midnight · 06-05-2014 4:08pm

tomasrojo wrote: »

(Also contains a claim that sports helmets "definitely" save lives, by preventing skull fractures, which, while it's a common claim, I've yet to see strong statistical evidence of. Possibly because skull fractures aren't a common cause of death? I read that somewhere, but I don't have a citation. Also, claims in article about sports helmets addressing "high impact" linear accelerations seems exaggerated for bicycle helmets, given the standard 20km/h drop test.)

What they don't mention is that the number of accidents for things like off-piste skiers have gone up probably because of improved safety gear.

And of course bike helmets aren't designed for the sort of speeds that skiers go at.

CramCycle · 06-05-2014 4:12pm

Capt'n Midnight wrote: »

And of course bike helmets aren't designed for the sort of speeds that skiers go at.

They're not designed for the speeds most cyclists go at.

boege · 06-05-2014 7:05pm

Apologies if this covered already but if your travelling abroad I suggest you check the fine print of your travel insurance.

Any accident on a bike may require a helmet to be worn or cover is invalid. Unfortunately I know this from a very sad case.

biomed32 · 06-05-2014 7:26pm

After not wearing a helmet in my youth while riding my mountain bike, I immediately begun wearing one when I switched to using a road bike in my twenties. Not only was it compulsory with training cycles but the skinny wheels and my weight at the time made me want to wear a helmet. Silly I know.

I am not suggesting it become compulsory to wear a helmet, I feel it's up to the cyclist to make that decision but I think if cyclists used them it might give a better impression for drivers, alas saying that I am not a driver and have never found it to be effective (run onto the footpath a couple times).

I can personally say that I will be continuing to wear a helmet. Maybe I cant fall properly but on the first occasion I slipped out on gravel and my head hit the deck first along with the left hand side of my body, landing me with a busted hip. I had a helmet on me at the time and needless to say it went into the bin the next day, cracked through.

In my most recent spill about a month ago, I was wearing my helmet again and fell off at speed after crossing wheels with a rider in front. My head again hit the deck first then the right hand side of my body, this time landing me with a hairline fracture of the wrist/thumb. The helmet again was cracked through.

In these two cases I have no doubt that I was spared a serious concussion or possible head injury as on both occasions I really felt I had my bell rung.

Just my two cents!

doozerie · 06-05-2014 8:03pm

biomed32 wrote: »

I am not suggesting it become compulsory to wear a helmet, I feel it's up to the cyclist to make that decision but I think if cyclists used them it might give a better impression for drivers, ...

But why should a cyclist feel the need to give any kind of impression to a driver?

A driver should not worry about whether a cyclist is dressed in a fashion that the driver considers appropriate. It should be irrelevant, as the driver should drive in a way that does not endanger the cyclist regardless of how they are dressed - so even if the driver believes that lack of a helmet means great danger, they fulfil all reasonable social responsibility by not doing something silly that will increase the danger. Unfortunately though, it is sometimes the case that a driver gets somehow offended by someone's choice of what to wear and use their self-fuelled outrage to justify all manner of illogical views and actions that can impinge on cyclists generally.

In fariness, most people are rational, and recognise that whether I wear a helmet or not is really none of their business or their concern. But there is a very vocal minority that are completely irrational. They don't go around asking every car driver whether their car has functioning air bags, working brakes, or non-bald tyres, yet they lose the plot when they see a cyclist without a helmet and feel the need to either remonstrate directly with them, or write to (or for!) a national newspaper to whine on about it, etc.

One of the many things that we as a society need to rid ourselves of, to have any hope of rational debate around the topic of helmets, is the moral outrage that we seem to feel entitled to employ when we see someone doing something that doesn't affect us in the slightest but which we feel "shouldn't be allowed, Joe!".

slideshow bob · 06-05-2014 9:02pm

biomed32 wrote: »

... I think if cyclists used them it might give a better impression for drivers

Alas, a relatively recent study (much quoted here) showed the contrary:

drivers were as much as twice as likely to get particularly close to the bicycle when he was wearing the helmet.

http://www.bath.ac.uk/news/articles/archive/overtaking110906.html

My most recent spill whilst commuting (close encounter with a bus leading to other issues) lead to an unpleasant crack in my face that a helmet didn't protect against.

Capt'n Midnight · 06-05-2014 9:24pm

biomed32 wrote: »

After not wearing a helmet in my youth while riding my mountain bike, I immediately begun wearing one when I switched to using a road bike in my twenties. Not only was it compulsory with training cycles but the skinny wheels and my weight at the time made me want to wear a helmet. Silly I know.

I don't think any is against helmets for higher risk activities like off-road or perhaps mass start races or probably even racing in general.

The point is that the average commuter plodding along probably won't benefit enough from a helmet to outweigh any risks taken because they feel safer, if you are in a collision with a motorist then you might as well be wearing a tea cosy.

RayCun · 07-05-2014 9:13am

Capt'n Midnight wrote: »

The point is that the average commuter plodding along probably won't benefit enough from a helmet to outweigh any risks taken because they feel safer, if you are in a collision with a motorist then you might as well be wearing a tea cosy.

People regularly post on here about accidents they've had - collisions or falling off for some other reason. Since they are still posting on here, we know that those accidents did not involve head-on collisions with cars travelling at high-speed.
But when people argue against helmets they always say, "yeah, that bit of plastic won't do you much good in a head-on collision with a car travelling at high-speed!!!!"

buffalo · 07-05-2014 12:04pm

RayCun wrote: »

People regularly post on here about accidents they've had - collisions or falling off for some other reason.

I came off in the high winds at Christmas. With my lack of helmet I broke my collarbone, and grazed my head. If I'd been wearing a helmet, I still would've broken my collarbone.

Does that act as sufficient counterpoint to the other anecdotes?

droidus · 07-05-2014 12:14pm

This is a reasonable summation of many of the points here - though i think lack of journey frequency for different modes of transport makes a bit of a dogs dinner of his stats:

http://www.howiechong.com/journal/2014/2/bike-helmets

"...It’s an unintuitive position to take. People have tried to reason with me that because I’ve spent so much money and time developing my brain, and the cost of an injury would be so devastating, it’s clearly more important to wear a helmet. But if we start looking into the research, there’s a strong argument to be made that wearing a bike helmet may actually increase your risk of injury, and increase the risk of injury of all the cyclists around you..."

RayCun · 07-05-2014 12:30pm

buffalo wrote: »

I came off in the high winds at Christmas. With my lack of helmet I broke my collarbone, and grazed my head. If I'd been wearing a helmet, I still would've broken my collarbone.

Does that act as sufficient counterpoint to the other anecdotes?

It illustrates the point. Helmets are not claimed to be magic hats that will protect from all injuries, and arguments against wearing helmets that come down to "they're not magic - you can still get injured!" are for that reason unconvincing. But they can reduce the seriousness of injuries.

droidus wrote: »

This is a reasonable summation of many of the points here - though i think lack of journey frequency for different modes of transport makes a bit of a dogs dinner of his stats:

http://www.howiechong.com/journal/2014/2/bike-helmets

There are quite a few problems with that article - failing to compare journey frequency as you point out, running together mandatory helmet laws with choosing to wear a helmet is another.
In the 'why helmets may be harmful' section
the NY Times stat (injuries increasing while cycling levels go down and helmet use goes up) is useless without more detail on the changing profile of cyclists in that period. Its a great example of the temptation to plot two things on the same graph and shout "Look!"

The Bath study says that drivers overtook closer when he wore a helmet. It also says that drivers overtook closer the further from the kerb he cycled, and he cycled further from the kerb when he wore a helmet :rolleyes:

CramCycle · 07-05-2014 12:38pm

RayCun wrote: »

It illustrates the point. Helmets are not claimed to be magic hats that will protect from all injuries, and arguments against wearing helmets that come down to "they're not magic - you can still get injured!" are for that reason unconvincing. But they can reduce the seriousness of injuries.

and increase the risk of others.

There are quite a few problems with that article - failing to compare journey frequency as you point out, running together mandatory helmet laws with choosing to wear a helmet is another.
In the 'why helmets may be harmful' section
the NY Times stat (injuries increasing while cycling levels go down and helmet use goes up) is useless without more detail on the changing profile of cyclists in that period. Its a great example of the temptation to plot two things on the same graph and shout "Look!"

It is an interesting coincidence though that in other areas such as Canada where some states introduced mandatory helmet laws that not only did the number of cyclists reduce, the number of head injuries significant enough to warrant hospital attention either stayed the same (ie more injuries per person cycling), or did not decrease in line relative to the number of cyclists (which would imply helmets at the very worst made no difference). From these two you can make a conjecture that either a) people cause head injuries and helmets have no population scale advantage/disadvantage or b) helmets do have a negative impact both on cycling levels and head injuries, although at what scale without, as you said, profiling the cyclists who keep cycling, it is impossible to know.

The Bath study says that drivers overtook closer when he wore a helmet. It also says that drivers overtook closer the further from the kerb he cycled, and he cycled further from the kerb when he wore a helmet :rolleyes:[/QUOTE]

RayCun · 07-05-2014 12:57pm

CramCycle wrote: »

It is an interesting coincidence though that in other areas such as Canada where some states introduced mandatory helmet laws that not only did the number of cyclists reduce, the number of head injuries significant enough to warrant hospital attention either stayed the same (ie more injuries per person cycling), or did not decrease in line relative to the number of cyclists (which would imply helmets at the very worst made no difference). From these two you can make a conjecture that either a) people cause head injuries and helmets have no population scale advantage/disadvantage or b) helmets do have a negative impact both on cycling levels and head injuries, although at what scale without, as you said, profiling the cyclists who keep cycling, it is impossible to know.

You can conjecture a lot of things.
Mandatory helmet laws reduce the number of casual adult cyclists, but have less effect on the number of children cycling, and they are more likely to have accidents.
Mandatory helmet laws annoy some people so much that they deliberately don't wear helmets when cycling dangerously, just to show they can, and then they can't.
Mandatory helmet laws have no real impact on the number of casual cyclists, which was on the decline anyway, and no real impact on the number of racing/MTBing cyclists, who wore helmets anyway, but the proportion of the latter as a percentage of cyclists has increased, and they are the ones more likely to have accidents.
More information needed.

tomasrojo · 07-05-2014 2:12pm

I don't have links to hand, but MHLs do reduce the numers of children cycling. Observations of children cycling in Alberta is one example that comes to mind, unless I misremember.

The numbers of journeys made by bike dropped in all jurisdictions that brought in a MHL, as far as I know. How that breaks down into casual cyclists, sports cyclists, etc. I don't know, but I agree that sports cyclists are unlikely to stop. A Norwegian study suggested that this was the reason for the rise in head injury rate post-MHL: the remaining cyclists were inherently more prone to taking risks. There are plenty of other theories: risk compensation, increased rotational acceleration, combinations thereof.

RayCun · 07-05-2014 2:29pm

yeah, I think a mandatory helmet law is a bad idea

doozerie · 07-05-2014 2:48pm

RayCun wrote:

You can conjecture a lot of things.

Indeed, and the claimed link between wearing a helmet and reduction in head injury is another example of just that, conjecture. As you say, more study is needed, but in the meantime it seems odd to me that many people treat assumed protection (from a helmet) as if it were a fact despite there being a lack of reliable scientific evidence to support that view.

A helmet might protect you in a collision, in some types of collision I’d certainly prefer to be wearing one than not (specifically, I’d like one if I drop to the ground from a stationary or almost stationary bike - I’ve done this without a helmet and came away with nothing more than a bruised head, a strong headache, and a fractured wrist, but given a choice I’d have a helmet on next time), in some types of collision the helmet will offer no benefit whatsoever, and in others still the helmet may cause more severe injuries than if you’d worn no helmet.

Adopting a view of either “everyone should wear a helmet” or “no-one should wear a helmet” seems ridiculous to me. Both views try to impose certainty where none exists. You don’t often encounter people publicly defending the argument that no-one should ever wear a helmet, they’d be roundly labelled as delusional or cranks, but people who argue that everyone should wear a helmet are guilty of the same blinkered view. Common sense lives somewhere between those two extremes and people will make their own choice about whether to wear a helmet and their choice may well change from one day to the next, and personally I see nothing wrong with that.

RayCun · 07-05-2014 3:03pm

It isn't really conjecture to say that a helmet offers some protection from injury. It's a shock-absorbing object between your body and the ground/other object.

CramCycle · 07-05-2014 3:09pm

RayCun wrote: »

It isn't really conjecture to say that a helmet offers some protection from injury. It's a shock-absorbing object between your body and the ground/other object.

It is not conjecture to say that the helmet has weight which increases the weight acting upon your neck in all situations that you are wearing a helmet.

It is however unproven if not misleading to imply that it only acts in a positive fashion in the case of an accident.

mrcheez · 07-05-2014 3:18pm

For me, helmet is more comfortable than without as it keeps the sweat out of my eyes (and stops the hair blowing around). Looks neater imho.

Apart from that, when I got side-swiped by a door opening on the bike lane and I flipped over landing on my head, I was fairly happy the helmet took the impact.

buffalo · 07-05-2014 3:23pm

doozerie wrote: »

Common sense lives somewhere between those two extremes and people will make their own choice about whether to wear a helmet and their choice may well change from one day to the next, and personally I see nothing wrong with that.

Get of here with your 'common sense' and reasonable middle ground! There's no place for your kind in giant mega-threads of doom!

Capt'n Midnight · 07-05-2014 4:55pm

RayCun wrote: »

It isn't really conjecture to say that a helmet offers some protection from injury. It's a shock-absorbing object between your body and the ground/other object.

It will protect you from some impacts.

But

It will cause some impacts and rotational injuries that would not otherwise occur because of the larger target area. It will offer no significant protection at speeds at which motorists drive, remember that the RSA free speed survey shows most motorists speed too. It increases risk taking by both cyclists and motorists. It deters casual cyclists , less cyclists, less facilities, less familiarity more risk.

A bicycle helmet is not a motorbike helmet, it is not a crash helmet, it is not designed to handle collisions with motorists. It's just there to offer a reasonable level of protection if you fall off your bike at 20Kmph.

If your intended use is for traffic then bicycle helmets aren't fit for purpose and you should really be wearing a proper motorbike helmet.

Capt'n Midnight · 07-05-2014 5:00pm

tomasrojo wrote: »

I don't have links to hand, but MHLs do reduce the numers of children cycling. Observations of children cycling in Alberta is one example that comes to mind, unless I misremember.

When it comes to young children's helmets the most important thing is to make sure they NEVER , wear a helmet unsupervised except when on a bike. Far too many children have been strangled by the straps getting caught in climbing frames, bunk beds etc.

doozerie · 08-05-2014 10:20am

RayCun wrote:

It isn't really conjecture to say that a helmet offers some protection from injury. It's a shock-absorbing object between your body and the ground/other object.

I never said it was conjecture that a helmet offers *some* protection from injury. In fact I gave an example of one scenario (a drop straight down onto the ground, mimicking one of the specific tests that are applied to helmets) where I believe it offers some protection. What I said is that it is conjecture to say that wearing a helmet reduces head injuries, by which I mean serious head injuries (a helmet would probably also reduce minor head injuries caused by friction, but then so would a soft hat). There remains a lack of sufficient reliable scientific evidence that wearing a helmet provides the kind of protection that people assume it will and that helmet manufacturers are happy to let people assume. There is also evidence to suggest that wearing a helmet increases certain risks, which should also be borne in mind.

That’s not an argument to not wear a helmet, incidentally, if someone wishes to wear a helmet then that is an entirely reasonable choice for them to make as far as I am concerned. What it is though, is an argument to apply some critical thinking to your reasons for wearing a helmet - what protection do you really believe it’ll provide?; is there good evidence to support that belief?; does the helmet conform to a safety standard that you are happy with (and, if not, should you buy a helmet that conforms to a “better” safety standard)?; is there a different helmet that’ll give you protection more suited to your needs?; do you really need a helmet at all?; etc.

Better to make an educated choice, if you choose to wear a helmet while accepting the limitations and potential pitfalls of doing so, than to just pop a helmet on your head and assume that you are automatically safer. Too many people do the latter - not only is this dangerous for them, but from their position of assumed security and safety some of them then deride those who choose not to wear helmets as if such a decision were completely illogical, and even suicidal, and they campaign to impose their entirely faith-based “logic” on everyone else via proposed mandatory helmet laws, etc.

stecleary · 08-05-2014 10:26am

I was knocked off my bike on Monday, 3 days later I still have a splitting head ache and the room keeps spinning. If I'd have had no helmet on I'm pretty sure it would be a lot worse.

droidus · 08-05-2014 11:21am

Maybe your conclusion is a result of your head injury?

LeoD · 08-05-2014 11:36am

Whatever about the pros and cons of helmets, you really have to take your hat off (pun semi-intended) to those that have convinced us that the same helmet design is suitable for both children piddling about on their bikes at walking pace and pro racers hurtling down mountains at 100+kmh.

CramCycle · 08-05-2014 11:47am

stecleary wrote: »

I was knocked off my bike on Monday, 3 days later I still have a splitting head ache and the room keeps spinning. If I'd have had no helmet on I'm pretty sure it would be a lot worse.

Have you been to a doctor? If not, I would not hang about. A helmet won't stop or improve a concussion, it may have helped or not other potential results from your accident but either way, see a doctor.

Beasty · 08-05-2014 1:29pm

stecleary wrote: »

I was knocked off my bike on Monday, 3 days later I still have a splitting head ache and the room keeps spinning. If I'd have had no helmet on I'm pretty sure it would be a lot worse.

Definitely make sure you see a doctor - these are not the sort of things you just "shake off"

stecleary · 08-05-2014 1:40pm

CramCycle wrote: »

Have you been to a doctor? If not, I would not hang about. A helmet won't stop or improve a concussion, it may have helped or not other potential results from your accident but either way, see a doctor.

Beasty wrote: »

Definitely make sure you see a doctor - these are not the sort of things you just "shake off"

spent 15 hours in Beaumont :mad:

Had a CT scan and all is good, I was just told it can take a few days for the headaches and spinners to stop.

doozerie · 08-05-2014 2:37pm

This sounds promising: Kali Phenom road helmet

Long ago, manufacturers figured out the formula to sell helmets, and it didn’t involve talking safety specifics. Vents, weight, and aesthetics are the name of the game, especially in the realm of road cycling.

It was only a matter of time before the pendulum swung the other direction. Now, a few helmet makers, like Kali Protectives, are talking less about ventilation and more about foam density and Cone-head technology.

AstraMonti · 09-05-2014 6:43pm

Here is an interesting piece http://www.ncbi.nlm.nih.gov/m/pubmed/24686160/

At realistic impact speeds of 5.4m/s (1.5m drop) and 6.3m/s (2.0m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3m/s) to unlikely (9.3% and 30.6% risk at 1.5m and 2.0m drops respectively).

tomasrojo · 10-05-2014 12:37am

Be interesting to see what commentary that elicits.

A few things occur to me off the top of my head.

Some potentially misleading turns of phrase:
"cycling injuries are more common than in any other summer sport" ... serious injuries or road rash, cuts and bruises? Serious head injuries figure much in that total?
"52,000 cyclists were injured in the US in 2010" ... out of how many cyclists in total?
"Head injuries account for approximately two-thirds of hospital admissions and three-quarters of fatal injuries among injured cyclists." ... how does that compare to pedestrians? Usually these stats are about the same for pedestrians, in studies I've seen.

It seems to be a variation on the standard drop tests, but using a greater range of heights and measuring linear acceleration instead of just examining the liner to make sure it hasn't cracked. Not sure how they map linear acceleration to risk of head injury. (On a minor note, 30% risk of severe head injury also is not really "unlikely"; I'd put it as "more unlikely than likely", but it's pretty high still.)

I think it's not controversial to say that helmets reduce linear acceleration (their whole point is to do so), especially at relatively low speeds (such as 6.3m/s or 23km/h), though perhaps the acceleration measurements themselves are a new addition to the field. The drop test isn't much like actually falling off a bike; no forward momentum, less likelihood of angular acceleration. Not that this type of test addresses angular acceleration anyway. There are a few papers, one from TRL in the UK, that state that these tests are fine, since forward velocity is irrelevant, and only the acceleration due to gravity matters. Never been sure why this is plausible. If it were true, falling off a bar stool onto your head would be as dangerous as falling off a bike travelling at 90km/h onto your head. Both could result in severe head injury, but it seems very unlikely that the likelihood is the same. At lower speeds, the likelihood would be similar.

The paper title is very strong, considering that they aren't actually measuring head injuries.

Capt'n Midnight · 11-05-2014 7:06pm

AstraMonti wrote: »

Here is an interesting piece http://www.ncbi.nlm.nih.gov/m/pubmed/24686160/

At realistic impact speeds of 5.4m/s (1.5m drop) and 6.3m/s (2.0m drop), bicycle helmets changed the probability of severe brain injury from extremely likely (99.9% risk at both 5.4 and 6.3m/s) to unlikely (9.3% and 30.6% risk at 1.5m and 2.0m drops respectively).

6.3m/s is 22.7Km/hr

Most urban roads are 50Km/h , a collision at 45Km/hr would have four times the energy of someone falling off their bike.

When you get to 60Km/hr it's seven times the energy - this is the average speed observed of cars in our 50Km zones - bike helmets just aren't designed to take vehicular impacts

WHEN you can get motorists obeying the existing speed limits, and bicycle helmets can take the impact at that speed then we can have a debate. Until then bike helmets just aren't capable of offering realistic protection in traffic.

82% of car drivers surveyed exceeded the 50km/h limit on urban national
roads, a marginal decrease of one percentage point on 2009 figures;
• 53% of these drivers exceeded the speed limit by 10km/h or more;
• The average speed of cars on urban national roads was about 11 km/h above
the 50 km/h posted speed limit. Furthermore, only 15% of drivers were
observed travelling below the speed limit and 6% were travelling between 80
and 100 km/h.

http://www.rsa.ie/Documents/Road%20Safety/Speed/Speed_survey_2011.pdf

Helmets - the definitive thread.. ** Mod Note - Please read Opening Post **

Comments

Helmets - the definitive thread.. Mod Note - Please read Opening Post