Benefits of wearinga helmet poll

always_tyred

MartinC1 wrote:

Surf Matt. Not having a go at you at all but I'm really interested to understand how it is that you, and your mates, know that you would be dead or brain injured if you hadn't been wearing helmets.

Didn't I just say that?

It is obvious though - Surf Matt is a surfer and a mountain biker. As such, he is perpetually quite close to brain death and even a minor blow can send him over the edge.

(ducks flying object)

MartinC1

It was a serious question. I'm really interested to know why people think the helmet has saved them and how they believe it's done it.

Surf-Matt

Martin - we all struck our heads directly on hard objects. We all had helmets on. We are all fine.

Whether the helmet saved us or not each time, they certainly lessened the impact.

I wasn't there with the other two but I hit a granite wall with a glancing blow having stacked at about 25-30mph. I was briefly out cold, took a big lump out of my leg and shredded my shoulder. The helmet cracked but stayed in one piece overall.

Always - and used to be a competing Kickboxer (many blows to the head) - I believe my remaining brain cell is having a hard time trying to cope

MartinC1

Surf Matt. Thanks for the reply. If I understand correctly then you believe the helmet was of benefit because it cushioned the blow. For me the next question would be to ask why you believe this energy absorption was sufficient enough to have any injury saving effect.

I don't think I agree with you so I've tried to explain why - it's a long post. I'm not anti helmet. I've worn one for about 25 years,indeed I've just ordered 2 new ones to replace their predecessors which are now past their sell by date. In this 25 years I've read through most of the available information on them and ended up very sceptical about the benefit they can provide. I'm concerned that many people over estimate the protection they can offer and I'm aware that the promotion of helmet wearing has several bad effects for cycling in general. Having played and been involved in rugby all through my life I'm also fairly familiar with blows to the head!

There are 3 quantities that need to be taken into account when you look at helmet effectiveness in an accident.

1. The amount of energy being dissipated through the head.

2. The amount of energy required in this impact to cause head injury.

3. The amount of energy absorbed by the helmet.

For the helmet to have any worthwhile effect then the helmet must absorb enough energy so that amount in 1 is reduced below 2 otherwise injury will occur.

So an objective analysis of a particular accident must take these into account and so too any general analysis of helmet effectiveness. I don't find personal anecdotes very useful because, although people have an intuitive belief that they were saved, they can't possibly have any real assessment of the factors involved. The belief that the helmet helped seems to be based on the assumption that helmets help.

Looking at the 3 quantities is difficult. None can be measured in real life. You can do tests to estimate 3 in laboratory conditions but testing 1 and 2 on people would be unethical. You can trawl the net and find various estimates for them all. How valid they are is debatable but they seem to show that 3 can be quite small compared with 1 and 2.

If you want to consider objectively how effective helmets are then it's worth just running through some of the factors that affect these 3 quantities.

1 is obviously affected by the total energy dissipated in the accident. If you cycle into something and come to a dead stop the it's easy to calculate, if you fly through the air, slide along the road, etc. then it gets more complicated. To work out how much of this is absorbed by your head is probably impossible. Current helmet standards generally only consider unassisted (i.e. no othere vehicle involved) cyclist falls at 10-12 mph or less because the energy involved in anything more is way beyond the design capability of a polystyrene helmet.

2 is hard to calculate. It will depend on many things including the type of blow. The head is constructed quite well by evolution to withstand direct blows on flat surfaces. It has a hard bony case and the brain is cushioned inside. Blows by pointy objects can cause more damage with lower energy because they can more easily crack the skull and damage what's inside. Rotational blows with much lower energy can cause extensive damage because they cause internal shear forces in the brain which disrupt nerve connections and blood vessels. It's worth noting that a cycle helmet is designed to mitigate blows of the first type, can do little about the second and may increase the chance and severity of the latter by increasing the effective size of the head.

3 is much more tractable. You can calculate it and test it in a lab by dropping a loaded helmet onto an anvil. There are various standards with varying testing regimes, you can find them on the net if you look. It's hard to find helmets manufactured to the more rigorous standards now, presumably they were too difficult to make at reasonable cost. The standard will give you an idea of the theoretical capability of a helmet. This will assume many things - e.g. helmet strength isn't compromised by a blow or age, correct alignment of the blow with the vents, correct fit, it's worn correctly and the blow is within it's design limits. There's a common mis-perception that even in a massive blow it will provide it's theoretical cushioning effect. This isn't true. Polystyrene absorbs energy by progressively deforming. If the blow has too much energy it can't deform quickly enough and will shatter or split. In this case it can only provide a fraction of it's theoretical energy absorption. A helmet that's split has failed and has provided less protection than it should.

Thinking about all of these things leads me to believe that although helmets are an attractive idea I'd be silly to expect anything more than the prevention of superficial injuries like gravel rash. It seems to me that in real life that they can only protect me against a fall that would do little damage. Of course there are the freak accidents where a small blow causes terrible damage and that a helmet might prevent these - but I'm just as likely to have one of these in the shower as on the bike.

robmanic1

Martin, didn't read you entire thread (life's too short!), I'm sure it's scientifically accurate, but as Matt states (and in my earlier thread) the best evidence is from personal experience. I've stacked at 15-20mph head-first into a tree, a ridng buddy of mine endo'd and landed head first, on both occasions I'm confident that wearing a helmet saved us both from severe head injuries. Now I can't back this up with scientific evidence, I don't need to , I'm not trying to convince anyone after all, just justifying my own preference for helmet wearing. And, as stated previously, I don't always wear one, I just apply the laws of probability and base my decision on that.

(still don;t know which box to tick though!)

MartinC1

Rob, you don't need to justify your preference, your view is just as valid as anyone's. What I feel uncomfortable about is when you say your view is evidence based. Anecdotes aren't evidence.

robmanic1

But surely "anecdotal" evidence is the best kind, otherwise we'd just believe everything we read based on other peoples research or anecdotes. The evidence I talk of IS based on personal experience, it's the only evidence I can rely on without prejudice. I take other folks comments on board, compare them with my own beliefs, based on personal exeprience, and make a judgement.

Surf-Matt

Martin - now I see where you are coming from.

It's not the same at all but I feel the same about "super" fuels (petrol and diesel) - NO evidence to show they work any better/give more mpg yet still people swear by them via marketing hype.

I used to have a rather pokey Golf R32 which was "meant" to use these fuels - I refused and the car was completely fine and went like stink.

My own helmet "evidence" was enough for me - the crash happened a while back and I'd not long been wearing a helmet. I now wear one at all times on a bike.

MartinC1

I think personal experience plays a big part in how we view things - it's human nature. We aren't always too logical either. I'm sure part of the reason I wear a helmet as much as I do is for the same reason I''ve had the same lottery numbers since it started. Having started with them it feels like you're tempting providence if you stop.

I think whether you ride on or off road makes a difference too. No evidence but it seems to me that the circumstances where a helmet may make a difference are more likely off road - you aren't going to be hit by a speeding car. On road there seems to be a contradiction - people wear helmets because traffic makes them feel unsafe but helmets don't mitigate that danger, only the simple off that no-one's really bothered about.

Personal experience is fine for making personal decisions. I'm certainly not including you guys in the next bit because you aren't saying what other people should do. There seems to be a conventional wisdom around that cycling helmets are a good thing and that cyclists should wear them. I just get really fed up with being told I should wear a helmet by people who know nothing at all about them.

Cunobelin

Robmanic1 wrote:

But surely "anecdotal" evidence is the best kind, otherwise we'd just believe everything we read based on other peoples research or anecdotes. The evidence I talk of IS based on personal experience, it's the only evidence I can rely on without prejudice. I take other folks comments on board, compare them with my own beliefs, based on personal exeprience, and make a judgement.

Which is why in my personal experience......................

More pedestrians are admitted through our A/E doors than cyclists. In each case a helmet could have saved injury. - Evidence?

always_tyred

I just heard someone on the radio - from the HSE I think - in relation to that poor family who lost a child in a canoeing accident.

They made the distinction between activities which:

(a) have a risk of serious injury

and activities which

(b) have a serious risk of injury

I think that cyling and being a pedestrian in an urban environment are probably on a par in terms of (a) because I guess that most of the risks are actually from the same source.

But in terms of (b) - that's my only disagreement with you, mate.

dazzawazza

Wearing a helmet saves me from a lot of verbal abuse from wifey so there's definitely less brain damage every day.

That's 200 posts; fantastic! Add another 150 after C+ change-over in 2007.

Clever Pun

dazzawazza wrote:

Wearing a helmet saves me from a lot of verbal abuse from wifey so there's definitely less brain damage every day.

I hear that.

I'm coming to the conclusion that I'll probably end up without the helmet for the hot light summer months (if I can do it without the earache), but when it gets colder and darker I'll start wearing the helmet again as there is white on the back of it and would help in me being seen.

I've had numerous offs in earlier years and never would a helmet have helped or hindered the situation (from what I can remember)

meanwhile

Surf-Matt wrote:

Martin - we all struck our heads directly on hard objects. We all had helmets on. We are all fine.

Whether the helmet saved us or not each time, they certainly lessened the impact.

For the 20th time... No. That's very poor reasoning.

This is naive physics, and its contradicted by (linked, above) expert testimony.

You're mistaking intention for performance; reality is more complex. A cushioning device designed and tested to offer cushioning at one level of impact may actually make impacts at other levels worse. This may seem counter-intuitive, but early boxing helmets are now notorious for having created more rather than less brain damage. Add to this the likely increased and very dangerous rotational element of impact, and there is no reason at all to believe that your helmet made you safer in a significant impact.

Also for the 20th (ok, approximately) time, a road bike helmet tops out at absorbing 300J of energy - that's around a push-up's worth. Compared to the amount of energy involved in the sort of crash that would worry me (around 4000J) that's tiny and practically benefitless.

What you actually did was trade somewhat effective prevention of facial scratches (easy to detect but trivial) for increased risk of brain injury (serious, but can be subtle and hard to detect.)

meanwhile

Robmanic1 wrote:

But surely "anecdotal" evidence is the best kind, otherwise we'd just believe everything we read based on other peoples research or anecdotes. The evidence I talk of IS based on personal experience, it's the only evidence I can rely on without prejudice. I take other folks comments on board, compare them with my own beliefs, based on personal exeprience, and make a judgement.

You can't have meaningful personal experience on which to draw on as to whether helmets work unless you have been in multiple crashes with and without helmets - at which point, the information is too late to do you any good...

Do you apply the same criteria to choosing medical treatments? "You're not bring that antibiotic near me - I want to see whether I die without it first..."

As for listening to other people's "anecdotal experience" - this is a process which historically lead to witch burning, a belief that heavy objects fall faster than slow ones, that flat earth theory, the evil of ethnic minorities, the arrival of Russian troops in Scotalnd (as evidenced by snow on their boots) and every other silliness you can think of. Maybe its not quite true that most people are idiots, but the numbers are close enough so that I wouldn't want to call it...

jam1ec

It would seem this logic is applied by some people at least. "You're not bringing that protective equipment near me - I want to see whether I die without it first..."

It is quite possible that a helmet is ineffective in an impact where the ground is perfectly smooth or evenly soft (boxing glove, or car bonnet even) but i can't help but think as you introduce any level of unevenness having a padded layer to even out the "spikes" will help, even if you skull still has to deal with the majority of the energy. This is best illustrated in the mountain bike environment with trees and rocks but kerb stones, cats eyes and loose stones no doubt have the same effect.

Heavy objects falling faster than light ones was proven false in the first instance (famously anyway) by a physical experiment not a calculation.

As an aside i have had a number of falls both with and without a helmet on, on each of the two occasions i was knocked unconscious i was not wearing a helmet.

always_tyred

meanwhile wrote:

As for listening to other people's "anecdotal experience" - this is a process which historically lead to witch burning, a belief that heavy objects fall faster than slow ones, that flat earth theory, the evil of ethnic minorities, the arrival of Russian troops in Scotalnd (as evidenced by snow on their boots) and every other silliness you can think of. Maybe its not quite true that most people are idiots, but the numbers are close enough so that I wouldn't want to call it...

There's a difference between intellect and knowledge. Many misconceptions arise from a reasonable processing of available information, with the emphasis on available.

The point is well taken though - put 10 people in a circle, whisper to one of them, "Do you wear pants under your cycling shorts" and see what you get back at the end!!

By the way, all other factors being equal, heavier objects DO fall faster than light ones unless they fall in a vacuum. Of course, the difference may not be perceptible.

A flat earth is not an unreasonable proposition if loads of people you know head off in boats to a flat horizon and never come back.

Surf-Matt

meanwhile wrote:

Surf-Matt wrote:

Martin - we all struck our heads directly on hard objects. We all had helmets on. We are all fine.

Whether the helmet saved us or not each time, they certainly lessened the impact.

For the 20th time... No. That's very poor reasoning.

This is naive physics, and its contradicted by (linked, above) expert testimony.

You're mistaking intention for performance; reality is more complex. A cushioning device designed and tested to offer cushioning at one level of impact may actually make impacts at other levels worse. This may seem counter-intuitive, but early boxing helmets are now notorious for having created more rather than less brain damage. Add to this the likely increased and very dangerous rotational element of impact, and there is no reason at all to believe that your helmet made you safer in a significant impact.

Also for the 20th (ok, approximately) time, a road bike helmet tops out at absorbing 300J of energy - that's around a push-up's worth. Compared to the amount of energy involved in the sort of crash that would worry me (around 4000J) that's tiny and practically benefitless.

What you actually did was trade somewhat effective prevention of facial scratches (easy to detect but trivial) for increased risk of brain injury (serious, but can be subtle and hard to detect.)

So you think hitting a wall at about 25mph would have just caused some facial scratches then?

I have worn protective headgear in many different guises.

Combat helmet in Army and RM exercises.
PPE hat on building sites.
Headgear for kickboxing.
Headgear for surfing a heavy reef break.
Riding hat on a horse.
Safety helmet for coasteering.
Crash helmet for race driving.
Crash helmet for motorcycling.
Safety helmet for abseiling/climbing.

and the list goes on.

What I DON'T do is waste hours trying to justify each use of headgear - I just put it on and trust that it does a good job - having "tested" the impact protection of at least half of that list, I have come to the conclusion that they do work - and very well.

So please don't pull the patronisation card. I'm an Engineer by degree. I know about impact testing, I know about scientific evidence. I also know that if there is an elevated risk of head injury and some appropriate head protection, I will wear it without question. As will most people.

meanwhile

Always Tyred wrote:

By the way, all other factors being equal, heavier objects DO fall faster than light ones unless they fall in a vacuum. Of course, the difference may not be perceptible.

Very wrong: drop a screw and a pillow and see which falls faster.

A flat earth is not an unreasonable proposition if loads of people you know head off in boats to a flat horizon and never come back.

Ummm, yes: no one ever survived a voyage across the North Sea or the Med until the C15th. Archaeologists are still looking for the Viking's secret invasion tunnel.

always_tyred

MartinC1 wrote:

Surf Matt. Thanks for the reply. If I understand correctly then you believe the helmet was of benefit because it cushioned the blow. For me the next question would be to ask why you believe this energy absorption was sufficient enough to have any injury saving effect.

I don't think I agree with you so I've tried to explain why - it's a long post......

I think anyone who puts this much effort into a post deserves to have it read!

Given that you wear a helmet but still have great concerns over their effectiveness (other than mass, ventilation and cool graphics, which of course are getting progressively better) you come cloest to my opinion.

Regarding the polystyrene deformation and fracture properties. Good point, well explained.

My understanding is that they have started glueing the cover on and forming the helmet around a cage in order to limit the fracture propogation.

Overall, though, polystyrene is undoubtedly used because it is CHEAP and we would be far better off using a foam, for example a polyurethane foam, which has a contiguous structure rather than one composed of independent particles.

meanwhile

Surf-Matt wrote:

meanwhile wrote:

Surf-Matt wrote:

Martin - we all struck our heads directly on hard objects. We all had helmets on. We are all fine.

Whether the helmet saved us or not each time, they certainly lessened the impact.

For the 20th time... No. That's very poor reasoning.

This is naive physics, and its contradicted by (linked, above) expert testimony.

You're mistaking intention for performance; reality is more complex. A cushioning device designed and tested to offer cushioning at one level of impact may actually make impacts at other levels worse. This may seem counter-intuitive, but early boxing helmets are now notorious for having created more rather than less brain damage. Add to this the likely increased and very dangerous rotational element of impact, and there is no reason at all to believe that your helmet made you safer in a significant impact.

Also for the 20th (ok, approximately) time, a road bike helmet tops out at absorbing 300J of energy - that's around a push-up's worth. Compared to the amount of energy involved in the sort of crash that would worry me (around 4000J) that's tiny and practically benefitless.

What you actually did was trade somewhat effective prevention of facial scratches (easy to detect but trivial) for increased risk of brain injury (serious, but can be subtle and hard to detect.)

So you think hitting a wall at about 25mph would have just caused some facial scratches then?

No: learn to read more carefully. I said that a helmet is fairly reliable in protecting against scratches, at a cost of increased risk of serious neurological injury in high speed impacts, where the helmets 200-300J of energy absorption is likely to be irrelevant. Even if the helmet functions to spec - and the evidence is that only a minority do.

I have worn protective headgear in many different guises.

...Disguised as a dolphin, disguised as a gnome...

Combat helmet in Army and RM exercises.
PPE hat on building sites.
Headgear for kickboxing.
Headgear for surfing a heavy reef break.
Riding hat on a horse.
Safety helmet for coasteering.
Crash helmet for race driving.
Crash helmet for motorcycling.
Safety helmet for abseiling/climbing.

and the list goes on.

What I DON'T do is waste hours trying to justify each use of headgear - I just put it on and trust that it does a good job - having "tested" the impact protection of at least half of that list, I have come to the conclusion that they do work - and very well.

Then you're assuming rather than acting from knowledge. Once again, the best available experts - testifying under oath - put the protection from modern bike helmets in a quite class from most of those others. You can verify their testimony by looking at the actual helmet specs and comparing them to the energy of a real crash.

So please don't pull the patronisation card. I'm an Engineer by degree. I know about impact testing, I know about scientific evidence. I also know that if there is an elevated risk of head injury and some appropriate head protection, I will wear it without question. As will most people.

Again: you are assuming that modern bike helmets are "appropriate". You're making a big deal about having an engineering degree, but you're ignoring actual hard numbers and expert testimony by engineers and neurologists. Modern bike helmets are less effective than those of 1990: the safety spec was watered down to levels where it is almost meaningless, so that helmets could be made easier to manufacture and to sell. Just because something is helmet shaped does not mean that protects.

Now, assuming that helmets are worthwhile and not researching the topic in the first place is not unreasonable - none of us would ever move if we researched very possible safety issue. But saying "I'm an engineer, so I know that anything shaped like a helmet must make me safer, and can therefore ignore helmet specifications, expert testimony, and real accident statistics" doesn't really fly.

always_tyred

meanwhile wrote:

Always Tyred wrote:

By the way, all other factors being equal, heavier objects DO fall faster than light ones unless they fall in a vacuum. Of course, the difference may not be perceptible.

Very wrong: drop a screw and a pillow and see which falls faster.

A flat earth is not an unreasonable proposition if loads of people you know head off in boats to a flat horizon and never come back.

Ummm, yes: no one ever survived a voyage across the North Sea or the Med until the C15th. Archaeologists are still looking for the Viking's secret invasion tunnel.

All other factors being equal
the difference may not be perceptible
unless they fall in a vacuum

:roll:

Try dropping the pillow and the screw under water, its a bit easier to see.

If you tip your head to one side, though, and drop a small screw and a small pillow into your ear, they would indeed take EXACTLY the same time to get to come out the other side.

I'm not going to debate the flat earth thing with you. I don't think that the entirity of human civilization was less intelligent than Meanwhile up to the 15th century. Indeed, some of our ancestors may even have been capable of understanding gravity and air resistance.

Surf-Matt

Okay then, I'm an engineer with massive experience of impact testing on numerous materials including polystyrene with the added benefit of having personal experience of a prevented head injury thanks to a cycle helmet.

Thin air offers less protection than polycarbonate and polystyrene.

This is from Cambridge Uni - Swansea (where I studied) is actually ahead of Cambridge with regards to research and funding but this will do for now - look at where polycarbonate and polystyrene lay in the graph. Yes it's basic dissertation stuff but it still proves a point.

http://www-materials.eng.cam.ac.uk/mpsi ... elmets.pdf

meanwhile

Always Tyred wrote:

MartinC1 wrote:

Surf Matt. Thanks for the reply. If I understand correctly then you believe the helmet was of benefit because it cushioned the blow. For me the next question would be to ask why you believe this energy absorption was sufficient enough to have any injury saving effect.

I don't think I agree with you so I've tried to explain why - it's a long post......

A standard helmet will take 12mph of energy in cushioning mode if it performs correctly in ideal circumstances. Assuming that Matt's body take 25mph out hit energy evenly distributed, his head alone took about 4 times this. The helmet may have subtracted 1/4 of this energy. If that was all the helmet did, there wouldn't be a case against wearing a helmet - except nuisance and cost - but it will also have increased the risk of a (very serious) rotational injury. So he gained a small to negligible benefit for the cost of increased risk of utter disaster. More serious, from the POV of road riders, is that evidence (linked above) that drivers treat helmeted riders much more aggressively.

Given that you wear a helmet but still have great concerns over their effectiveness (other than mass, ventilation and cool graphics, which of course are getting progressively better) you come cloest to my opinion.

If you think the graphics look cool, we definitely disagree.

Regarding the polystyrene deformation and fracture properties. Good point, well explained.

My understanding is that they have started glueing the cover on and forming the helmet around a cage in order to limit the fracture propogation.

Overall, though, polystyrene is undoubtedly used because it is CHEAP and we would be far better off using a foam, for example a polyurethane foam, which has a contiguous structure rather than one composed of independent particles.

The ultimate problem is that cushioning can only result from foam depth - and worse, the depth of foam required to cushion a higher velocity impact to a constant maximum deceleration goes with the square of the velocity. Deeper foam increases the risk of rotational injury, messes with balance, etc, and probably weighs more and interferes with ventilation. Oh, and once you have that depth of foam you need a shell that will keep it together when it takes several thousands J of kinetic energy. This is called a motorbike helmet, and people won't cycle commute in them.

Given that the UK has only about 100-150 cycle deaths a year, and accident studies show that deaths would be halved if cyclists just stopped doing obviously stupid things, I'm not sure that a moon-landing style technological assault on helmet design is required...

meanwhile

The ultimate problem is that cushioning can only result from foam depth - and worse, the depth of foam required to cushion a higher velocity impact to a constant maximum deceleration goes with the square of the velocity.

Ie a 25mph helmet would have to be FOUR TIMES as thick as a current Snell helmet designed for a 12mph impact. And remember, that's just to absorb the kinetic energy of the head - if the head leads the impact, so it takes part of the energy of the rest of the body, SPLOSH.

meanwhile

Surf-Matt wrote:

Okay then, I'm an engineer with massive experience of impact testing on numerous materials including polystyrene with the added benefit of having personal experience of a prevented head injury thanks to a cycle helmet.

Thin air offers less protection than polycarbonate and polystyrene.

This is from Cambridge Uni - Swansea (where I studied) is actually ahead of Cambridge with regards to research and funding but this will do for now - look at where polycarbonate and polystyrene lay in the graph. Yes it's basic dissertation stuff but it still proves a point.

http://www-materials.eng.cam.ac.uk/mpsi ... elmets.pdf

No, it doesn't. It just contains some meaningless blurb without references are usful content "A bike helmet must absorb LOTS of energy". Tres scientique! "Compare and describe the aesthetics (colour, texture, pattern) of many different types of helmets, and discuss how the market influences the style and appearance of each design." - Is this from someone's Nobel acceptance speech?

The Snell spec for a cycle helmet is 300J; most helmets fail this. Come back and tell me i. what speed the helmet will fail at if it just takes the mass of the head ii. what speed it will fail at if it takes the mass of the whole body. (Clue: 300J is the energy of a decent push-up...)

Oh, and this isn't "basic dissertation stuff" unless you went to the Poly From Hell - it looks more like a resource for GCSE students. (Hint: an engineering dissertation wouldn't ask readers to compare helmet colour and graphics, and it would give references and quantify data instead of saying "Lots!")

meanwhile

Always Tyred wrote:

I'm not going to debate the flat earth thing with you. I don't think that the entirity of human civilization was less intelligent than Meanwhile up to the 15th century.

It's irrelevant, but you have a firm grasp of the Point Not Being Made there: my point was that common opinion is usually wrong. Educated people knew throughout the middle ages that the earth was round (you could see this from a ship mast, and the educated would read the work of Greek philosophers who had calculated its radius correctly). "What everyone knows" is usually wrong where it isn't based on definite testable, grudgingly accepted knowledge.

Surf-Matt

meanwhile wrote:

Surf-Matt wrote:

Okay then, I'm an engineer with massive experience of impact testing on numerous materials including polystyrene with the added benefit of having personal experience of a prevented head injury thanks to a cycle helmet.

Thin air offers less protection than polycarbonate and polystyrene.

This is from Cambridge Uni - Swansea (where I studied) is actually ahead of Cambridge with regards to research and funding but this will do for now - look at where polycarbonate and polystyrene lay in the graph. Yes it's basic dissertation stuff but it still proves a point.

http://www-materials.eng.cam.ac.uk/mpsi ... elmets.pdf

No, it doesn't. It just contains some meaningless blurb without references are usful content "A bike helmet must absorb LOTS of energy". Tres scientique! "Compare and describe the aesthetics (colour, texture, pattern) of many different types of helmets, and discuss how the market influences the style and appearance of each design." - Is this from someone's Nobel acceptance speech?

The Snell spec for a cycle helmet is 300J; most helmets fail this. Come back and tell me i. what speed the helmet will fail at if it just takes the mass of the head ii. what speed it will fail at if it takes the mass of the whole body. (Clue: 300J is the energy of a decent push-up...)

Oh, and this isn't "basic dissertation stuff" unless you went to the Poly From Hell - it looks more like a resource for GCSE students. (Hint: an engineering dissertation wouldn't ask readers to compare helmet colour and graphics, and it would give references and quantify data instead of saying "Lots!")

It was issued by Cambridge Uni Materials Engineering department. And have you forgotten to look at the "scientific" graph rather conveniently?

Find a wall, headbutt it as hard as you can from several angles.
Return and repeat with a cycle helmet on and see what you think.

You may revel in pedantry and wallow in scientific "data" that you have swiped off the internet but cycle helmets are worth wearing. As are shoes, underwear, shorts, gloves and cycle glasses. When I see a helmetless rider, I just think "pillock." Not very scientific but then I only have one life and I'd rather look after it.

Oh and you need to look up the word "guise" which is not the same as "disguise."

meanwhile

Surf-Matt wrote:

It was issued by Cambridge Uni Materials Engineering department.

That still doesn't make it the "dissertation" you claim, or mean that the unreferenced claim written by God knows who (the main page says that much of the content was provided by "industry partners") that bike helmets absorbs "lots!" of energy means more than the 200J that test labs, manufacturers, and standards bodies say.

And have you forgotten to look at the "scientific" graph rather conveniently?

Oooh, a graph! That proves it's science. It's a great graph though, in that it shows that foams are better cushioning materials than ceramics - about what you'd expect from a page aimed at 14 year olds.

Find a wall, headbutt it as hard as you can from several angles.
Return and repeat with a cycle helmet on and see what you think.

Ah. The "My imaginary experiment agrees with me so I must be right" principle. In this case ignoring:

1. My claim is that helmets work well in low speeds and poorly in high speed collisions, and that I (and probably you) can't run at 25mph

2. What you imagine and reality probably have no connection anyway.

You may revel in pedantry and wallow in scientific "data" that you have swiped off the

It's called "research".

internet but cycle helmets are worth wearing. As are shoes, underwear..

I'm really not interested!

When I see a helmetless rider, I just think "pillock."

After or before you try to work out what undies they are wearing?

Not very scientific but then I only have one life and I'd rather look after it.

If this was really true, you'd actually have done some research and made sure you bought safety gear that stood some chance of working. You say you didn't, so the helmet you are wearing is probably from the vast majority of placebo benefit only headgear. Nicely done!

dondare

Now try this: find a wall and don't bang your head against it.

Cyclists who wear helmets seem to bang their heads far more frequently than those who don't. Perhaps they take more risks.