Helmets and injury prevention

[Capricorn]

smart boy - now go to bed...

ironic

[johannrissik]

I wear a helmet because it makes me look cool.... I think? #enduro

Through those rose tinted goggles everything must look cool...

[V12man]

ironic

Putting bits and pieces back together - seatbelts would be a good thing.... if used and present in all taxi seats... scoreboard not looking good today.

[Capricorn]

Putting bits and pieces back together - seatbelts would be a good thing.... if used and present in all taxi seats... scoreboard not looking good today.

yikes, sounds nasty

[porqui]

......

OK, now that I have your attention, I have a serious question. Does anyone have links to reliable studies around helmet usage and injury prevention. A lot of what I have come across seems biased. Or full of assumptions.

 

 

No studies needed.

Enough convincing evidence witnessed and experience gained.

 

I will take my chances with a helmet.

[V12man]

and more importantly (of late anyway), is the fact that there is no helmet out there by any brand (except one) that designs helmets that can prevent concussion. You are very likely to walk away from a nasty tumble with very superficial external injuries thanks to that helmet now in pieces or severely cracked, but that concussion you will have to some degree or other, is an internal injury and it is brain damage.

I am curious about this brand that can prevent concussion - there are limits to what a helmet can achieve - even the best ones won't prevent concussion if the impact is big enough - you just don't have enough distance in a helmet shell to decellerate the brain slowly enough to prevent injury.

 

Work out the g forces applied in a 20kph to zero stop - assume it's a tree that compresses 1cm and the helmet liner compresses fully and is 2cm thick - you can further assume there is no scull fracture or penetration injury, and the brain has 0.5cm fluid cushioned space to move before impacting the scull (we need an engineer or physicist here... ) you will see the massive increase in g forces when you remove the 2cm compressible layer  of the helmet - the numbers are insane.... especially when you remember we even see concussion symptoms in aerobatic pilots/fighter pilots from time to time - staying conscious in a +8 to -8 transition is pretty tricky... although not directly caused by impact related trauma, there is an element of that - especially when accumulated over time.

[V12man]

yikes, sounds nasty

Messy - given I was 3rd on call

[Captain Fastbastard Mayhem]

Messy - given I was 3rd on call

yoh.... 

[Capricorn]

I am curious about this brand that can prevent concussion - there are limits to what a helmet can achieve - even the best ones won't prevent concussion if the impact is big enough - you just don't have enough distance in a helmet shell to decellerate the brain slowly enough to prevent injury.

 

Work out the g forces applied in a 20kph to zero stop - assume it's a tree that compresses 1cm and the helmet liner compresses fully and is 2cm thick - you can further assume there is no scull fracture or penetration injury, and the brain has 0.5cm fluid cushioned space to move before impacting the scull (we need an engineer or physicist here... ) you will see the massive increase in g forces when you remove the 2cm compressible layer  of the helmet - the numbers are insane.... especially when you remember we even see concussion symptoms in aerobatic pilots/fighter pilots from time to time - staying conscious in a +8 to -8 transition is pretty tricky... although not directly caused by impact related trauma, there is an element of that - especially when accumulated over time.

 

perhaps my enthusiasm is poorly phrased This company is the first i know that has purposely designed the helmet to prevent concussions at speeds envisaged for the application, and as you were starting to realize, it's not a standard helmet by any means. It's more an airbag for cyclists: the Hovding.

 

We are all likely to sneer at its design, i know i did, but the point of highlighting this bit of innovation is that someone out there decided current helmets are crap when it comes to protecting the head and brain. I think all lid manufacturers need to go back to square one and design our favorite noggin_jars with more appropriate levels of protection, not just the mip-service currently provided.

 

A study into the efficacy of airbags in reducing vehicular accident fatalies for driver-side impacts indicated a 37% percent reduction in fatalies when head level airbags were used as well, as opposed to a 26% reduction when only torso-protecting side airbags were used in the car.

 

While the reduction in vehicular accident mortality has decreased since the inclusion of airbags, it's a system of protection comprising engineered crash mitigation (crumple zones, air bags, seatbelts) as well as driver education, there's clearly some merit to airbags that if designed properly, should widespread acceptance on bicycles. I think downhill skiiing has an inflatable torso protector that's already had some success on the skiing world cup circuit.

[V12man]

perhaps my enthusiasm is poorly phrased This company is the first i know that has purposely designed the helmet to prevent concussions at speeds envisaged for the application, and as you were starting to realize, it's not a standard helmet by any means. It's more an airbag for cyclists: the Hovding.

 

We are all likely to sneer at its design, i know i did, but the point of highlighting this bit of innovation is that someone out there decided current helmets are crap when it comes to protecting the head and brain. I think all lid manufacturers need to go back to square one and design our favorite noggin_jars with more appropriate levels of protection, not just the mip-service currently provided.

 

A study into the efficacy of airbags in reducing vehicular accident fatalies for driver-side impacts indicated a 37% percent reduction in fatalies when head level airbags were used as well, as opposed to a 26% reduction when only torso-protecting side airbags were used in the car.

 

While the reduction in vehicular accident mortality has decreased since the inclusion of airbags, it's a system of protection comprising engineered crash mitigation (crumple zones, air bags, seatbelts) as well as driver education, there's clearly some merit to airbags that if designed properly, should widespread acceptance on bicycles. I think downhill skiiing has an inflatable torso protector that's already had some success on the skiing world cup circuit.

Aha - yes - the airbag thing will certainly be useful - what I would like to see is an airbag  contained inside a hard shell helmet - so that it blows up outside of the shell and then you would have the benefits of both models in play - remember - airbags don't prevent any kind of intrusion injury - so that nice short sharp twig on our proverbial tree in the model will do considerably less damage  with a hard shell - assuming one can aim properly....

 

If you do the math, then you can model an airbag fairly well by increasing the compressible shell to say 6cm, and in another version to say 20 cm - the deeper the compressible layer, the better the g forces look (from your brains perspective anyway)

 

I have just had an idea that a brake distance calculator might help us with the calc - back soon.

 

edit - this does seem to work out the physics - http://hyperphysics.phy-astr.gsu.edu/hbase/crstp.html

 

http://hyperphysics.phy-astr.gsu.edu/hbase/images/astp3.gif

  Develop expression If the vehicle speed is v = m/s = ft/s = km/hr = mi/hr

and the coefficient of friction between the tires and the road is μ = ,

the stopping distance is d = m = ft.

 

This shows that a figure of 75U gives a stopping distance of 2cm from 20kph - and I am pretty sure u is measure in g - see my table below.

 

g(u)     stopping distance

 

75   2cm

30   5cm

15   10cm

10    15cm

5     31cm

 

 

This makes intuitive sense to me, because it is independent of weight, and to drop the g force on the brain by half, you have to double the stopping distance - any engineers out there that are better at math than me?

[Capricorn]

Aha - yes - the airbag thing will certainly be useful - what I would like to see is an airbag  contained inside a hard shell helmet - so that it blows up outside of the shell and then you would have the benefits of both models in play - remember - airbags don't prevent any kind of intrusion injury - so that nice short sharp twig on our proverbial tree in the model will do considerably less damage  with a hard shell - assuming one can aim properly....

 

If you do the math, then you can model an airbag fairly well by increasing the compressible shell to say 6cm, and in another version to say 20 cm - the deeper the compressible layer, the better the g forces look (from your brains perspective anyway)

 

I have just had an idea that a brake distance calculator might help us with the calc - back soon.

 

I forgot to offer advice wrt calculation of deceleration: use the constant acceleration equations as a first stab. But you'll need stoppage distance:

 

if you assume stoppage distance, say over the full thickness of the EPS liner in a typical bicycle helmet, you can get the necessary deceleration.

[johannrissik]

No studies needed.

Enough convincing evidence witnessed and experience gained.

 

I will take my chances with a helmet.

Really? 

No studies needed?

Why ever not? 

And if one were, for example, to consider the bigger picture?

 

BTW: I also take my chances with a helmet.

[Captain Fastbastard Mayhem]

Really? 

No studies needed?

Why ever not? 

And if one were, for example, to consider the bigger picture?

 

BTW: I also take my chances with a helmet.

because quite simply the benefits of riding with a helmet far outweigh the perceived benefits of riding without one. 

 

No study will be able to show, without introducing SIGNIFICANT bias, that the non use of helmets is better. It's one of those things that has sufficient evidence to allow someone to dismiss any other study citing the benefits of helmetlesness as simple twaddle.

 

Much like the climate change denialists harping on about the "3% of scientists that disagree"

[henningvr]

Through those rose tinted goggles everything must look cool...

You have no idea....

 

I too take my chances with a helmet rather than without. Got the scar to prove it too. 1993, Bridgestone MB1, just before Butterworth (Transkei), raining hard, head meets barrier. If I wore a helmet back then, I wouldn't have had to spend a few days there, and we would have reached Cape Town at least a week sooner. Chances are good that I wouldn't have this scar too, and possibly a few extra brain cells. That's debatable though.

 

It's a common sense thing, no?

[Capricorn]

Aha - yes - the airbag thing will certainly be useful - what I would like to see is an airbag  contained inside a hard shell helmet - so that it blows up outside of the shell and then you would have the benefits of both models in play - remember - airbags don't prevent any kind of intrusion injury - so that nice short sharp twig on our proverbial tree in the model will do considerably less damage  with a hard shell - assuming one can aim properly....

 

If you do the math, then you can model an airbag fairly well by increasing the compressible shell to say 6cm, and in another version to say 20 cm - the deeper the compressible layer, the better the g forces look (from your brains perspective anyway)

 

I have just had an idea that a brake distance calculator might help us with the calc - back soon.

 

edit - this does seem to work out the physics - http://hyperphysics.phy-astr.gsu.edu/hbase/crstp.html

 

http://hyperphysics.phy-astr.gsu.edu/hbase/images/astp3.gif

  Develop expression If the vehicle speed is v = m/s = ft/s = km/hr = mi/hr

and the coefficient of friction between the tires and the road is μ = ,

the stopping distance is d = m = ft.

 

This shows that a figure of 75U gives a stopping distance of 2cm from 20kph - and I am pretty sure u is measure in g - see my table below.

 

g(u)     stopping distance

 

75   2cm

30   5cm

15   10cm

10    15cm

5     31cm

 

 

This makes intuitive sense to me, because it is independent of weight, and to drop the g force on the brain by half, you have to double the stopping distance - any engineers out there that are better at math than me?

 

that's a variation of the constant acceleration equation. If you apply those equations directly, you get a more direct answer without having to worry about congruency between coefficients of friction and the deceleration provided by an EPS or inflatable thingy.

 

So i would proceed by trying to understand what average acceleration/deceleration causes concussion, and work out stoppage distances (or thickness) of the EPS liner/ volume of displaced air from the inflatable thingy to cause that deceleration. the specific deceleration, or deceleration per meter of stoppage distance can be used as a measure of the hardness of the EPS liner required, which in turn will determine how much EPS material is required to effect the desired deceleration. 

 

Doing these simple enough sums will very easily show why current helmet designs are useless when it comes to the real danger of having our bells rung: concussion.

[Headshot]

You have no idea....

 

I too take my chances with a helmet rather than without. Got the scar to prove it too. 1993, Bridgestone MB1, just before Butterworth (Transkei), raining hard, head meets barrier. If I wore a helmet back then, I wouldn't have had to spend a few days there, and we would have reached Cape Town at least a week sooner. Chances are good that I wouldn't have this scar too, and possibly a few extra brain cells. That's debatable though.

 

It's a common sense thing, no?

My anecdotal direct experience:

 

As a kid I was quite reckless on my old racer with bars turned up. Coming back from the shop my chommies and i tossed a packet of sugar or something between us. The last throw was poor and as I stretched for the package I went otb. Slid along nicely on my lovely Adidas nylon jacket and had my bare head impact on old stone kerb. No concussion, just a nice bloody cut requiring stitches at casualty. 

 

 

On a ride in the Cedarberg, also many years back a friend crashed hard doing nearly 50kph. I know this because he passed me when I had 48kph on my computer. He went straight onto his head. I found him sitting, very dazed and confused, surrounded by the lumo orange shell and polystyrene bits from his helmet. It was utterly destroyed. He was not - concussed yes and a few cuts and scrapes on his body but no broken head. I wonder how his skull would have looked without that helmet sacrificing itself?

 

 

Even if a helmet does no more than prevent surface injuries, its better than nothing IMO. A fractured skull is extremely serious I am led to believe and a helmet can do a lot to prevent that too I would imagine.

 

Wonder if these helmet deniers have ever ridden down a DH track or raced an enduro without a helmet?