Re: Speed and the fear of falling off

For all discussions about this "lively" subject. All topics that are substantially about helmet usage will be moved here.
Peter F
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helmets from Speed and the fear of falling off

Postby Peter F » 4 Jun 2020, 8:59pm

CyberKnight wrote:I ride dependant on the road conditions , how much i can see and how well i know the road .
I had a front wheel lock up at very slow speed and went over the bars needing 15 stitches to my face , its not just speed that hurts .

I hit a sheep at about 15 mph. It was hiding behind a bush and it lept out into the road as I passed. Over the bars, hand hit the road first followed by my hip then rolled onto my back and cracked my helmet. Couple of nasty cuts on my hand and a massive bruise on the top of my leg/hip. But headcwas fine thanks to my helmet. Sheep make me very nervous now.

mikeymo
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Re: Speed and the fear of falling off

Postby mikeymo » 4 Jun 2020, 9:05pm

Peter F wrote:But headcwas fine thanks to my helmet.
ssshhh. Don't say that!

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Cugel
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Re: Speed and the fear of falling off

Postby Cugel » 5 Jun 2020, 7:43am

mikeymo wrote:
Peter F wrote:But headcwas fine thanks to my helmet.
ssshhh. Don't say that!


Ha ha - too late!

If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion.

Best not to rely on the things, really; and to look out for the sheep etcetera instead.

It's remarkable that so many experienced cyclists, especially the ones who have fallen off, don't recognise that a head is rarely banged in a cycling fall, sheep-involved or otherwise. When the head is involved, it's generally the face wot gets it. A helmet generally offers no protection to your face, unless its a-one o' them full-face MTB things (a sensible article to wear when MTBing, in my own opinion). In fact, a helmet might even make your face (or neck) injury worserer as it levers your jaw harder into the road.

How was the sheep, by the way. I yam a-one o' them exasperated humans now less concerned about my own species (stupid lot, we are) than I am about the innocent beasts being punished by stupid humans all over the place.

Cugel

tim-b
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Re: Speed and the fear of falling off

Postby tim-b » 5 Jun 2020, 8:19am

Hi
snip "If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion./snip

Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

Peter F
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Re: Speed and the fear of falling off

Postby Peter F » 5 Jun 2020, 9:26am

Cugel wrote:
mikeymo wrote:
Peter F wrote:But headcwas fine thanks to my helmet.
ssshhh. Don't say that!


Ha ha - too late!

If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion.

Best not to rely on the things, really; and to look out for the sheep etcetera instead.

It's remarkable that so many experienced cyclists, especially the ones who have fallen off, don't recognise that a head is rarely banged in a cycling fall, sheep-involved or otherwise. When the head is involved, it's generally the face wot gets it. A helmet generally offers no protection to your face, unless its a-one o' them full-face MTB things (a sensible article to wear when MTBing, in my own opinion). In fact, a helmet might even make your face (or neck) injury worserer as it levers your jaw harder into the road.

How was the sheep, by the way. I yam a-one o' them exasperated humans now less concerned about my own species (stupid lot, we are) than I am about the innocent beasts being punished by stupid humans all over the place.

Cugel


My head hit the road with sufficient force to split the helmet. Had I not been wearing it I would have had a nasty bump or a cut on my head. It didn't save my life, it just stopped me bashing my head. My hand had two nasty cuts because of stones on the surface so that could easily have been the back of my head.

I don't rely on a helmet, I do take care. You had to be there to realise just how concealed the sheep was until the last minute. I had actually backed off due to sheep, had I not I would have been doing 20mph+. I am now even more cautious around them.

No idea about the sheep. When I got up off the road it was nowhere to be seen. It was in ok enough shape to run off I guess.

Marcus Aurelius
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Re: Speed and the fear of falling off

Postby Marcus Aurelius » 5 Jun 2020, 10:02am

tim-b wrote:Hi
snip "If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion./snip

Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise
Regards
tim-b

Quite right. Up until the point where it actually fails structurally, it’s doing it’s job. Once it disintegrates it’s no longer doing anything useful. It’s like tyres. Up until you get under rotation, they are doing their job ( when braking ). Once the under rotation starts, they aren’t bringing anything useful to the party

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Cugel
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Re: Speed and the fear of falling off

Postby Cugel » 5 Jun 2020, 10:19am

tim-b wrote:Hi
snip "If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion./snip

Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise
Regards
tim-b


Very droll. The helmet works by transforming a head bang into heat and noise.

Cugel

tim-b
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Re: Speed and the fear of falling off

Postby tim-b » 5 Jun 2020, 10:26am

Hi
Very droll. The helmet works by transforming a head bang into heat and noise. Hee hee hee.
Cugel

Scientific fact: Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise


Regards
tim-b
~~~~¯\(ツ)/¯~~~~

pwa
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Re: Speed and the fear of falling off

Postby pwa » 5 Jun 2020, 10:32am

Cugel wrote:
tim-b wrote:Hi
snip "If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion./snip

Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise
Regards
tim-b


Very droll. The helmet works by transforming a head bang into heat and noise. Hee hee hee.

Cugel

It does take energy to make heat and noise. That's one reason I prefer quiet Shimano freehubs to noisy Hope ones. :D

(When Graham lifts this digression into the Helmets section, this contribution is probably going with it)

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Cugel
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Re: Speed and the fear of falling off

Postby Cugel » 5 Jun 2020, 11:15am

tim-b wrote:Hi
Very droll. The helmet works by transforming a head bang into heat and noise. Hee hee hee.
Cugel

Scientific fact: Helmets don't only absorb energy by being "crushed flat", they also transfer it elsewhere in the structure where there may be deformation and/or breakage, and some impact energy changes to heat and to noise

Not droll either, maybe there's a troll though?

Regards
tim-b


How much of each energy type in them various transfers then? Showuz yer data.

Cugel

Jdsk
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Re: Speed and the fear of falling off

Postby Jdsk » 5 Jun 2020, 11:30am

Cugel wrote:If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion.

If I understand correctly you haven't seen the helmet after this impact.

How can you know whether it served a useful purpose in this instance or not?

Thanks

Jonathan

Peter F
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Re: Speed and the fear of falling off

Postby Peter F » 5 Jun 2020, 2:53pm

Jdsk wrote:
Cugel wrote:If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion.

If I understand correctly you haven't seen the helmet after this impact.

How can you know whether it served a useful purpose in this instance or not?

Thanks

Jonathan


Get a cycle helmet and hit it with a mallet hard enough to cause it to split. Then imagine someone hitting you on the head that hard with the mallet.

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Cugel
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Re: Speed and the fear of falling off

Postby Cugel » 5 Jun 2020, 3:39pm

Jdsk wrote:
Cugel wrote:If the helmet was just "cracked" it performed no function other than to deplete your wallet and add to the landfill. To be of any functional use, the polystyrene must be crushed flat. This will absorb enough head-bang force to reduce the degree of headache and might even mean no-concussion rather than light-concussion.

If I understand correctly you haven't seen the helmet after this impact.

How can you know whether it served a useful purpose in this instance or not?

Thanks

Jonathan


The poster said "cracked". I take this to mean "only cracked" and therefore "not crushed".

Of course he may have meant "utterly crushed" in which case I would have agreed with him that the helmet saved his head from significant force where the helmet over it was so-crushed.

A cycling hat can be cracked by dropping it all by itself from a short height. The plastic shell is extremely thin/fragile and seems to serve no force-absorbing purpose other than to contain the polystyrene and sport the free advert hoarding the cyclist carries about everywhere. Some will claim that it's aerodynamic. Ha!

I do recall early cycling hats that were just polystyrene with no covering shell. They made me wear one in a race in 1989 I think it was. Now they were sweaty great things! It looked like one had a primitive horseshoe crab sitting on one's head, confused that it wasn't in the sea or at least on a beach.

When one or two disintegrated when merely nudged or looked at a bit hard, they started putting plastic shells on them too. Then they were not just sweaty hot but quite heavy and everyone comlained about the neck ache.

Cugel

Peter F
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Re: Speed and the fear of falling off

Postby Peter F » 5 Jun 2020, 7:28pm

Thanks for derailing my post Cugel. I'm new to this forum so was unaware that my mere mention of my helmet would result in you steaming in and it getting moved.

For the record, it wasn't the plastic shell that was cracked, that was intact. It was the polystyrene at the back of the helmet that split in two, fully. It looked like it had been hit hard with a blunt object such as a road.

You weren't there and you didn't see the helmet so please stop trying to use this post to push your own agenda.

Thank you.

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Mick F
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Re: Speed and the fear of falling off

Postby Mick F » 5 Jun 2020, 8:17pm

I have a thread on here somewhere ..................

Get a helmet, hold it upside down by the chin straps, and put a plastic bag in it full of wet sand about the size of your head.
Drop it onto hard concrete from 6ft.

How many times can you do this before the helmet cracks?

viewtopic.php?f=41&t=79382&start=75

I dropped the helmet three times from head-height. The first two times it bounced and appeared undamaged.
Third time I dropped it, it landed with a thud.
Mick F. Cornwall