Helmet split and dented, jersey holed, arm gashed, groin strained, yes i've come off

[Wobblers]

To some extent the foam should compress but by splitting it reduces a larger amount of the force. The outer shell should remain intact to hold it on the head, providing it is designed correctly.
If you drop a glass, dropping it onto the floor it shall smash. Dropping it onto something spongy and it shall slow it down, by dropping it into something that compresses and cracks (like a helmet) you slow it down and remove the force.

Good article here as well in case anyone wants it:
http://www.bhsi.org/general.htm

Did you actually read the article you linked to?

To help, here's a quote:

Helmets designed to handle major crash energy generally contain a layer of crushable foam. When you crash and hit a hard surface, the foam part of a helmet crushes, controlling the crash energy and extending your head's stopping time by about six thousandths of a second (6 ms) to reduce the peak impact to the brain. Rotational forces and internal strains are likely to be reduced by the crushing.

They should not split or crack. A lid that has cracked is a lid that has failed in its purpose.

 

[Wobblers]

Unfortunately i can't send any pics of the helmet, i haven't that capability. After i found it i checked it for any dents or similar and it was ok. It proved that by saving me from a nasty bump! I suddenly came off and that was it. Within a split second my head made contact with the tarmac,and though it was a shock to the system i also felt the comforting feel of cushioned poly' instead of skull fracturing tarmac! Therefore i'm glad that my decision to wear a helmet over the years saved me from potential serious injury.
My injuries didn't however stop me from cycling down to the pub last night, in fact i had to cycle as i couldn't walk....and i wore my helmet!

Firstly, since your helmet split, it provided you with less protection than you realise. It takes more energy than a 13 mph impact to fracture a skull. However, it most likely did save you from an unpleasant scalp wound - and that's something that is certainly worthwhile.

Now we've got that out the way, I'm glad it wasn't worse. One question: when you say you have a sore thumb, can you grip things with it or tie your shoe laces? If not, get yourself down to A&E now - as you may have broken or dislocated your thumb. Likewise, if the pain doesn't subside or your thumb swells up, get it looked at.

GWS!

 

[black'n'yellow]

Oh if you want a pair of riggers boots let us know. Going to cut one of them lengthwise to show their construction. Discarded by a family member who feels they no longer give the required protection.

I could be interested - is the toe cap steel or polystyrene..??

 

[black'n'yellow]

Then your understanding is wrong.

then perhaps you should put us all straight? I think the point is that a cracked polystyrene core is not necessarily the sign of a helmet that has failed to do its job.

They do not test all helmets. They test all helmet designs. Just like they don't test all cars with crash test dummies....

That's just semantics. Of course they do not test every single helmet. It was pretty clear to most people what the OP meant.

 

[snorri]

Who the heck goes through rubbish looking for freebies

Recyclists.

 

[Linford]

From a reliable source:

Are you implying that the force to split a lid at 13mph is not enough to incur a brain injury, and there are many instances of pedestrians sustaining a brain injury through tripping and banging their head on the kerb.

 

[black'n'yellow]

From a reliable source:

I don't see how that supports anything you've said..?

 

[snorri]

.
Would you take a pair of rigger boots from a skip/bin & having only cleaned them up(make them look nice) then go onto expect them to offer the same protection as a pair of the same boots bought new?

I threw out a perfectly good pair of safety footwear which I had received free of charge from my employer but which were the wrong size for me. Actually I threw them in the bin of a local charity,I would be shocked if this act has altered their protective qualities.

 

[Wobblers]

Then your understanding is wrong.

And even the BHSI article he linked to said his understanding was wrong...

 

[Smokin Joe]

My mate once went through next doors wheely bin and found a condom.

Unfortunately, like the OP he found it split on impact...

 

[Smokin Joe]

Are you implying that the force to split a lid at 13mph is not enough to incur a brain injury, and there are many instances of pedestrians sustaining a brain injury through tripping and banging their head on the kerb.

So you recommend we all wear one when out walking?

 

[Octet]

I know I said I wouldn't continue as I would get into an endless loop although it is only human to debate a point.

When this receives a direct impact force, the styrofoam is intended to compress and in this way spread and reduce the force that is passed onto the skull, thus reducing linear accleration of the brain.

This is correct, and the styrofoam is designed to compress as I stated originally and as I am stating again.
Although what you are failing to understand is that when the helmet cracks it means that it sustained enough force to fracture. If the helmet had not fractured then it would indicate that the force applied to the helmet was not enough to exceed it's rating and doesn't suggest that it did or didn't work.
When the helmet fractured it doesn't mean it didn't do it's job and it doesn't mean it was worthless, all it means is that the helmet hit the ground with more force then it could cope with from a structural point of view. Using an old helmet would of potentially meant it had a weakened structure and so didn't protect to as higher standard as it could but the point that it cracked means that it did reduce some of the force.

As I said earlier on, regardless of whether it reduced the force by 25 Newtons or 100 Newtons... it still reduced the force and so reduced the impact force to one that didn't cause serious injury. Without it, he would of received the full amount which could of resulted in a more serious injury.

 

[theclaud]

then perhaps you should put us all straight?

I think this invitation might be superfluous...

 

[snorri]

My mate once went through next doors wheely bin and found a condom.
Unfortunately, like the OP he found it split on impact...

I think you're stretching it a bit SJ.

 

[Linford]

So you recommend we all wear one when out walking?

Given the amount of hostility shown to anyone who dare suggest that head protection might help reduce the effects of an impact, I'd say that the vocal minority are just winning this one on decibels at the moment