A helmet saved my life -- believe it



P

Peter Clinch

Guest
Clive George wrote:

> Go on then - what static load do you reckon the skull can take sideways?
> And what load if it arrives in a careless fashion, as a lorry wheel is
> wont to do?


Don't know, but I imagine that leaving the scene equally rapidly will
make a considerable difference compared to being parked there indefinitely.

Note the above presupposes no answers, just throws another variable in
to consider.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected]undee.ac.uk http://www.dundee.ac.uk/~pjclinch/
 
C

Colin McKenzie

Guest
Marc Brett wrote:

> For all you doubting-Thomases who think helmets don't work in real-world
> collisions with vehicles.
>
>
> Bike helmet crushed, but head fine
> http://www.madison.com/tct/news/index.php?ntid=133934
>
> A white paneled delivery truck ran over a UW-Madison graduate student's
> head on Division Street Friday afternoon and, except for a concussion,
> he wasn't hurt.


A quick google reveals:
<http://www.reporter-times.com/?module=displaystory&story_id=29691&format=html>

....a similar incident involving an 11-year-old and no helmet.
Children's skulls are supposed to be weaker than adults'

Also what the Americans call a truck we would call a pickup.

Colin McKenzie

--
No-one has ever proved that cycle helmets make cycling any safer at
the population level, and anyway cycling is about as safe per mile as
walking.
Make an informed choice - visit www.cyclehelmets.org.
 
C

Colin McKenzie

Guest
Chris Eilbeck wrote:

> Marc Brett <[email protected]> writes:
>>A white paneled delivery truck ran over a UW-Madison graduate
>>student's head on Division Street Friday afternoon and, except for a
>>concussion, he wasn't hurt.

>
> Now go and repeat the experiment without the helmet.


It's been done - see my other post.

Though I now realise that this incident involves a van, not a pickup
(or a truck).

Colin McKenzie


--
No-one has ever proved that cycle helmets make cycling any safer at
the population level, and anyway cycling is about as safe per mile as
walking.
Make an informed choice - visit www.cyclehelmets.org.
 
R

Rob Morley

Guest
In article <[email protected]>, Niall Wallace
[email protected] says...
have been relatively little force involved.
>
> I am trying to visualise this an all i am seeing is lots of body roll with
> the inside lower than the outside, suggesting there is more weight on the
> inside suspension than the outside.. But thats on a car without Anti-roll
> bars and on a roundabout turning right.
>


Consider the diagram of a vehicle where X is the centre of mass. In
order for it to turn to the right, a force must be exerted at the
tyre/road interface. This force is transmitted through the tyres and
suspension to the sprung mass of the vehicle.
___________
| |
| |
inertia <---- |_____X_____|
| | | |
--- --> --- --> turning force


This can be simplified to:

<----|
|
|---->

As the car body has some freedom of movement by virtue of the
suspension, this will result in it rolling to the left, as the left side
suspension is loaded and compressed and the right side suspension is
unloaded and extended. If there is sufficient acceleration (sharpness
of turning) and traction (tyre grip) the right side suspension will
fully extend. At this point if the tyre attached to that suspension
runs over something then the only force exerted on that object will be
that necessary to accelerate the unsprung mass (wheel and suspension
components) over the object - the sprung mass acts only as a relatively
stable attachment point.
 
D

dkahn400

Guest
On May 15, 11:19 pm, "Niall Wallace" <[email protected]>
wrote:

> > If the truck was turning hard the inside wheels would have been
> > unloaded, so if it was an inside tyre that went over him there might
> > have been relatively little force involved.

>
> I am trying to visualise this an all i am seeing is lots of body roll with
> the inside lower than the outside, suggesting there is more weight on the
> inside suspension than the outside.. But thats on a car without Anti-roll
> bars and on a roundabout turning right.


Without active suspension a car will corner with the inside bodywork
higher than the outside, not lower. Look at something like a Renault 5
which has torsion bar suspension and a large amount of travel so the
effect is particularly obvious.

<www.philwight.co.uk/images/renault5.JPG>

--
Dave...
 
N

Niall Wallace

Guest
"dkahn400" <[email protected]> wrote in message
news:[email protected]
> On May 15, 11:19 pm, "Niall Wallace" <[email protected]>
> wrote:
>
>> > If the truck was turning hard the inside wheels would have been
>> > unloaded, so if it was an inside tyre that went over him there might
>> > have been relatively little force involved.

>>
>> I am trying to visualise this an all i am seeing is lots of body roll
>> with
>> the inside lower than the outside, suggesting there is more weight on the
>> inside suspension than the outside.. But thats on a car without Anti-roll
>> bars and on a roundabout turning right.

>
> Without active suspension a car will corner with the inside bodywork
> higher than the outside, not lower. Look at something like a Renault 5
> which has torsion bar suspension and a large amount of travel so the
> effect is particularly obvious.
>
> <www.philwight.co.uk/images/renault5.JPG>
>


I realised the **** up in my thinking while walking for the bus this
morning.

If it was the way roudn I said then no one would ever have a problem being
sucked off or a roundabout (childrens play thing) and you wouldn't lift the
inside wheels when cornering at the mechanical limit.

So what was I thinking about leaning to the right on a right hander... clue
2 wheels.

Doh!!!!!
Niall
 
C

Chris Malcolm

Guest
Nick <[email protected]> wrote:
> burt wrote:
>> "Marc Brett" <[email protected]> wrote in message
>> news:[email protected]
>>> For all you doubting-Thomases who think helmets don't work in real-world
>>> collisions with vehicles.
>>>
>>> Bike helmet crushed, but head fine
>>> http://www.madison.com/tct/news/index.php?ntid=133934

>>
>> Just posted the response below:
>>
>> "Burtthebike says:
>>
>> This story is complete, total, utter nonsense.
>>
>> It may be true that the cyclist and the truck were in collision, but to
>> claim that the cycle helmet saved his life after the truck ran over his head
>> merely demonstrates that the cyclist was most definitely suffering from
>> concussion. No cycle helmet will protect your head if you get run over by a
>> relatively small car, let alone a truck! Hogwash dressed up to sell helmets
>> and make the cyclist feel good.
>>
>> We've only got his word for it that it ran over his head, and given that
>> that is impossible, the rest of his story must be open to question. As one
>> of the other posters asked, where are the witnesses and why did no-one get
>> the licence plate?
>>
>> Urban myth in the making. Believe this and demonstrate your gullibility and
>> lack of independent thought."
>>

> I don't know about heads you're probably right it. Maybe it pinched the
> helmet and poped his head out without actually going over it.


> However one of my friends did get knocked off and a car went right over
> his forearm with no significant damage. He did have a very clear tyre
> pattern on his arm to prove that it happened.


I know a few people who've had a car tyre run over their foot. No
damage at all, not even a bruise afterwards.

I think a lot of the people posting to this thread were looking out of
the window during the school physics lessons :)

--
Chris Malcolm [email protected] DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]
 
S

Simon Brooke

Guest
in message <[email protected]>, Chris Malcolm
('[email protected]') wrote:

> Nick <[email protected]> wrote:
>> burt wrote:
>>> "Marc Brett" <[email protected]> wrote in message
>>> news:[email protected]
>>>> For all you doubting-Thomases who think helmets don't work in
>>>> real-world collisions with vehicles.
>>>>
>>>> Bike helmet crushed, but head fine
>>>> http://www.madison.com/tct/news/index.php?ntid=133934
>>>
>>> Just posted the response below:
>>>
>>> "Burtthebike says:
>>>
>>> This story is complete, total, utter nonsense.
>>>
>>> It may be true that the cyclist and the truck were in collision, but to
>>> claim that the cycle helmet saved his life after the truck ran over his
>>> head merely demonstrates that the cyclist was most definitely suffering
>>> from concussion. No cycle helmet will protect your head if you get run
>>> over by a relatively small car, let alone a truck! Hogwash dressed up
>>> to sell helmets and make the cyclist feel good.
>>>
>>> We've only got his word for it that it ran over his head, and given
>>> that that is impossible, the rest of his story must be open to
>>> question. As one of the other posters asked, where are the witnesses
>>> and why did no-one get the licence plate?
>>>
>>> Urban myth in the making. Believe this and demonstrate your gullibility
>>> and lack of independent thought."
>>>

>> I don't know about heads you're probably right it. Maybe it pinched the
>> helmet and poped his head out without actually going over it.

>
>> However one of my friends did get knocked off and a car went right over
>> his forearm with no significant damage. He did have a very clear tyre
>> pattern on his arm to prove that it happened.

>
> I know a few people who've had a car tyre run over their foot. No
> damage at all, not even a bruise afterwards.


Me sir. Except in my case it was an articulated lorry; however it has to be
said it was mostly empty. OTOH I've had a cow stand on my foot, and
suffered broken toe in consequence - which was jolly uncomfortable.

I was involved in a car crash once - I wasn't driving - after which an
impression of my arm could clearly be seen in the outside of the (Volvo)
car door, as the steel had been wrapped or pressed around my arm in the
impact. I suffered a couple of cracked ribs, probably where my elbow was
driven into my rib cage - but my arm wasn't even bruised. Impacts are
funny things, and the human body is much stronger and more resilient than
you'd think.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; better than your average performing pineapple
 
D

David Martin

Guest
On May 17, 9:46 am, Chris Malcolm <[email protected]> wrote:

> I know a few people who've had a car tyre run over their foot. No
> damage at all, not even a bruise afterwards.


Me sir!, me sir!

> I think a lot of the people posting to this thread were looking out of
> the window during the school physics lessons :)


That's cos we'd read the textbook from cover to cover and couldn't be
arsed to listen to the teacher read it to us as well, insisting we
took down what she was saying as dictation. It really annoyed her that
we tried our best to ignore her but still could answer any of the
questions she asked without being flustered.

...d
 
D

DavidR

Guest
"Simon Brooke" <[email protected]> wrote
>
> Not necessarily. The air pressure in the tyres is somewhere between 30
> and
> 100psi. I think - I'm not sure - that a human skull ought to resist that
> much pressure. I have no problem believing a truck went over his head
> without breaking his skull, although I wouldn't like to guarantee you'd
> always get away with it.


There is a difference between the pressure of a tyre and the force due to
weight exerted on whatever it passes over. Even if the tyre is flexible
enough to distribute the lorry's weight round the head, the road *under*
the head certainly won't.
 
D

DavidR

Guest
"Niall Wallace" <[email protected]> wrote
>
> I am trying to visualise this an all i am seeing is lots of body roll
> with the inside lower than the outside, suggesting there is more weight
> on the inside suspension than the outside.. But thats on a car without
> Anti-roll bars and on a roundabout turning right.


The American term of *anti-sway* bars would be better for these devices.

Anti-roll bars only modify the body attitude, they do not affect the weight
(force) of the tyres on the road or the tendency for a vehicle to roll over
if cornered too hard.

Conversely, a car that sways a lot (eg, 2CV) may merely be due to soft
suspension, not a tendency to roll over.
 
N

Nigel Randell

Guest
"Simon Brooke" <[email protected]> wrote in message
news:[email protected]
> in message <[email protected]>, Marc Brett
> ('[email protected]') wrote:
>
>> For all you doubting-Thomases who think helmets don't work in real-world
>> collisions with vehicles.
>>
>>
>> Bike helmet crushed, but head fine
>> http://www.madison.com/tct/news/index.php?ntid=133934
>>
>> A white paneled delivery truck ran over a UW-Madison graduate student's
>> head on Division Street Friday afternoon and, except for a concussion,
>> he wasn't hurt.

>
> Apart from concussion, he would not have been hurt anyway. Simple test:
> put
> a rock in a helmet, run the truck over it. Helmet crushed, rock undamaged.
> Put a cake in a helmet, run the truck over it. Helmet crushed, cake
> crushed.
>
> The reason the skull doesn't crush is because it's about 300 times
> stronger
> than the helmet, and has evolved over many millions of years to survive
> major impacts and crushing injuries. The helmet is irrelevant, it crushes
> anyway. If what's inside the helmet is strong, it won't crush. It what's
> inside the helmet isn't strong, it will crush. Human skulls are very
> strong. Cycling helmets are very weak.
>



300 times stronger? Do you have a reference for that? Also are the results
of the cake and rock experiment in the public domain?

The third scenario would be to put a skull (or even better, a whole head) in
a helmet and run a truck over it - this result would be most relevant to the
discussion in hand.

--

Nigel
 
A

Andrew Price

Guest
On Mon, 21 May 2007 21:08:57 +0100, "DavidR" <[email protected]>
wrote:

[---]

>Conversely, a car that sways a lot (eg, 2CV) may merely be due to soft
>suspension, not a tendency to roll over.


Good example. 2CVs were extremely difficult to roll over.
 
T

Tony Raven

Guest
Andrew Price wrote on 22/05/2007 20:31 +0100:
> On Mon, 21 May 2007 21:08:57 +0100, "DavidR" <[email protected]>
> wrote:
>
> [---]
>
>> Conversely, a car that sways a lot (eg, 2CV) may merely be due to soft
>> suspension, not a tendency to roll over.

>
> Good example. 2CVs were extremely difficult to roll over.


I remember a review of the Renault 5, another car with lots of body
roll, many years ago which noted it cornered as well on two wheels and a
door handle as most cars did on four wheels.

--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell
 
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Rob Morley

Guest
In article <[email protected]>, Andrew Price
[email protected] says...
> On Mon, 21 May 2007 21:08:57 +0100, "DavidR" <[email protected]>
> wrote:
>
> [---]
>
> >Conversely, a car that sways a lot (eg, 2CV) may merely be due to soft
> >suspension, not a tendency to roll over.

>
> Good example. 2CVs were extremely difficult to roll over.
>

Surely that's because their tyres are three inches wide and they don't
do more than 45mph? :)
 
A

Alistair Gunn

Guest
Rob Morley twisted the electrons to say:
> Surely that's because their tyres are three inches wide and they don't
> do more than 45mph? :)


Doesn't it follow on from there that the reason there used to be a 24
hour 2CV endurance race was because it took that long? <grins>
--
These opinions might not even be mine ...
Let alone connected with my employer ...
 
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Rob Morley

Guest
In article <[email protected]>, Alistair Gunn
[email protected] says...
> Rob Morley twisted the electrons to say:
> > Surely that's because their tyres are three inches wide and they don't
> > do more than 45mph? :)

>
> Doesn't it follow on from there that the reason there used to be a 24
> hour 2CV endurance race was because it took that long? <grins>
>

Yesterday I was reading an account of a "run what yer brung" drag race
between a 2CV and a Renault 4 - those guys really know how to have fun.
:)
 
D

DavidR

Guest
"Rob Morley" <[email protected]> wrote
>>
>> Good example. 2CVs were extremely difficult to roll over.
>>

> Surely that's because their tyres are three inches wide and they don't
> do more than 45mph? :)


Actually, if tyre width is important, their width to weight ratio is
greater than most cars.
 
P

Peter Clinch

Guest
Rob Morley wrote:

> Surely that's because their tyres are three inches wide and they don't
> do more than 45mph? :)


I am reminded of a glorious newspaper ad Citroen once did for the 2CV,
where they pointed out it had as many wheels as a Rolls Royce, more room
than a Porsche ("we don't need a silly plastic luggage rack on the back
of /our/ car!") and faster than a Ferrari: "at it's top speed of 72 mph
it can easily overtake a Ferrari doing 60 in the slow lane".

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/