Impact Speed

[david k]

You do not under any circumstance decide the basis on which I reply to anything. Is that clear enough for you?

No, you replied to a question regarding the 'survey' is that clear to you?

 

[Licramite]

BS/EN 1078

I don't need to translate them , this is your project. (just thought you knew how to would have been useful)
"100J isn't awful lo, go on splat calculator and say drop a 5kg body (a head weighs about 10lb), you won't have to drop it very far to acheive 100j. - 2m jusy gave 98t"
By Jove I think he's got it!
You are right 100J is not a lot, it's the equivalent of standing astride your bike and falling sideways, once you start cycliing you are already outside the parameters that the helmet was designed to withstand.Maybe you start to realise now why so many people are not impressed with " My helmet sdaved my life.."?
I was being generous with the 100J, a helmet could only manage 85J and still pass.
still think it's worthwhile doing the maths for a 25MPH impact?

Developers of the HANS used crash test dummies in their testing procedures and found the head can briefly encounter 25 'G's', amounting to about 250 pounds, in a 35 mph impact. Gravitational forces are dependent on speed, and a doubling of speed quadruples the 'G-forces'.

sorry had the qoute wrong (never rely on memory). I based mine on Snell , yes BS/EN1078 is crap init. Hence the buy a helmet from the states the standard is better. - but even Snell only goes upto a 5G impact.

I'm not trying to defend helmets or wearing them or not, I agree thier protective qualities are low. - there peramiter of usefulness is limited after all they are involved in what 13% (see earlier post) of accidents.
I think I have demonstrated if you have an accident at over 17mph your outside the snell standard.They are designed for low speed impacts, and as 60% of bike accidents are simply the rider falling over the standards are designed for that sort of impact. - It's good to understand how it works, A compression zone of as little a 5mm can reduce the G the brain is subjected to by as much as 1/5

But I also wanted to show how fragile the human skull is to, and how easily the brain can be damaged within the skull - the tread is "Impact speed"- I wanted to show and understand the consequences of impact speed.
you bang on about evidence - well this is it. with no bias, I'm just trying to use maths to explain and understand how effective (or ineffective) helmets are.

maybe instead of saying thier useless we won't wear them , maybe it should be , thier useless we want better ones.

 

[david k]

No, once again for the extremely hard of understanding, my comments were not specifically by reference to that.
Now, is there any point to this? If not, just stop.

Stop if you like, I was questioning srw about the survey anyway when you replied, because I'm a nice courteous person I replied to you.

 

[Licramite]

25mph = 20.8G your head weight of 5kg will increase to 90Kg give an impact force of 1390j
but if your helmet gave you 6mm of crush zone it would reduce your G buy 6G so 14.8G , reduces your headweight to 74kg giving an impact of 1080j

 

[benb]

depends how you read it, in both cases the head wasnt hurt. in cases where the head would have scratched the helmet would have protected the user from scratches. In cases where the head wouldnt have scratched it made no difference

And in the second case, how exactly did the helmet do its job, as you claimed?

 

[srw]

I'm a nice courteous person

Oh no. You've consistently put thoughts into others' mouths - even when specifically asked not to. That's not courtesy, that's rudeness.

 

[david k]

And in the second case, how exactly did the helmet do its job, as you claimed?

ben, are you having a laugh? i didn't claim that or didn't mean it to read that way and have cleared that up several times, then you go on and ask the same question again!
in the second case wearing of a helmet made no difference, is that clear enough or will you ask the question yet again?

 

[david k]

Oh no. You've consistently put thoughts into others' mouths - even when specifically asked not to. That's not courtesy, that's rudeness.

no, i started by asking questions, then summarised them, if your views or anyone elses were interpreted incorrectly then this being an open forum they/you have the opportunity to clear it up

suggesting incorrectly that ive consistantly put thoughts into other peoples mouths is rude

 

[srw]

no, i started by asking questions, then summarised them, if your views or anyone elses were interpreted incorrectly then this being an open forum they/you have the opportunity to clear it up

suggesting incorrectly that ive consistantly put thoughts into other peoples mouths is rude

Welcome to my ignore list. You are a numpty with a single-track mind - bending others' words to suit yourself.

I'm sorry that you will find that rude of me.

 

[david k]

Welcome to my ignore list. You are a numpty with a single-track mind - bending others' words to suit yourself.

I'm sorry that you will find that rude of me.

dont mention it

 

[david k]

So do you have a point about impact speed and helmet effectiveness that needs clearing up?

Do you know everything about the subject to suitably 'clear up'? Or was this just an attempt to keep the thread going when it had come to a natural end?

 

[Little yellow Brompton]

Developers of the HANS used crash test dummies in their testing procedures and found the head can briefly encounter 25 'G's', amounting to about 250 pounds, in a 35 mph impact. Gravitational forces are dependent on speed, and a doubling of speed quadruples the 'G-forces'.

sorry had the qoute wrong (never rely on memory). I based mine on Snell , yes BS/EN1078 is crap init. Hence the buy a helmet from the states the standard is better. - but even Snell only goes upto a 5G impact.

I'm not trying to defend helmets or wearing them or not, I agree thier protective qualities are low. - there peramiter of usefulness is limited after all they are involved in what 13% (see earlier post) of accidents.
I think I have demonstrated if you have an accident at over 17mph your outside the snell standard.They are designed for low speed impacts, and as 60% of bike accidents are simply the rider falling over the standards are designed for that sort of impact. - It's good to understand how it works, A compression zone of as little a 5mm can reduce the G the brain is subjected to by as much as 1/5

But I also wanted to show how fragile the human skull is to, and how easily the brain can be damaged within the skull - the tread is "Impact speed"- I wanted to show and understand the consequences of impact speed.
you bang on about evidence - well this is it. with no bias, I'm just trying to use maths to explain and understand how effective (or ineffective) helmets are.

maybe instead of saying thier useless we won't wear them , maybe it should be , thier useless we want better ones.

Forget G all of the standards use J and the measuement is how many J will the helmet stand before it breaks... For the record you think 100J is "Crap" ? Yet the EN single test is 90J and the Snell 110J, how wonderful do you think the Snell standard is now?

How about, they are useless, they have always been useless ( you do know how the standard came about ?) and inline with every other H&S protocol we want PPE to be the very last method and not the first one? When there are safer roads, drivers, vehicles and cycle paths , then and only then is it worth looking at PPE.

 

[david k]

I was merely hoping for your damascene moment when you come to realize that that which you wish to foist on others is not the panacea you seem to imagine.

False claim that I have tried to foist anything on anyone

For me this is what brings any helmet debate to the end of the discussion, claiming that any person making any slightly positive remarks for helmets are "forcing your views on others" and "you think helmets will save you in any given situation" which most of us know is complete rubbish and the last line of defense for those opposing it.

Still its marginally better than the other defense, hiding behind, "I'm not against helmets, I am just against compulsion" despite nobody mentioning compulsion!

 

[david k]

You are a compulsionist. Everything you say on the subject is in that context.

You hate people who wear helmets. Everything you say on the matter is in that context

 

[Twilkes]

Helmet-lovers - you will go on my first whistle.

Helmet-lover-haters - you will go on my second whistle.

And once you've gone, maybe the rest of us can sit down and have our tea.