Helmet strength.

True - but by then you'd be *well* into fatal impacts.

....and anyway we're not talking about twatting it with a shovel
weakening it [1] we're talking about minor bumps weakening it.

[1] I'm prepared to believe there might be some measurable degredation
of the helmet after me twatting it with a shovel - even the gel coat
must offer *some* minor protection and that gets cracked by the shovel
edge.

 

Yeah. That's what shocked me when I was knocking seven shades of shit
out of it. The more obvious it became that the helmet shell was pretty
much indestructable the more it brought home to me how weak neck/brain
tissue is in comparison.

I have a strong feeling that if there had been a head in the helmet as
I was twatting it the neck would have broken fairly early on in the
process and the brain would be mush by the end.

Reminded me of an army officer mate telling me the challenger tank was
impervous to a direct hit. "Of course the people in it would be dead."
he said cheerfully.

 

I only mentioned 2m height as unless you're in a Luge contest, most people
tend not to crash at ground level.

The point which I was trying and apparently failing to make was something
like this:

1) Take a couple of identical helmets, all new and out of the box.
2) Stick a crash dummy in one and fling it at a hard surface at, say 30 mph.
3) Take another helmet and beat it with a shovel 20 times.
4) Stick a crash dummy in it and fling it at a hard surface at 30 mph.

Would you rather be wearing the first or second helmet? Mr Toad seems
insistent that it would make no difference, but I'd be willing to bet that
the "pre-distressed" helmet would certainly fail first.

 

That's *not* the point you're making. You're supporting the 'helmets
suffer serious structural weakness after minor bumps' side of the
argument.

I'm saying that the GRP shell of a helmet is nigh on indestructable and
even a helmet that had suffered a minor bump would certainly not
fracture following 'survivable' impacts.

The 100 bangs with the shovel were proving that the first minor bump
(the one that caused me to deem the helmet useless) had done **** all
meaningful damage at all.


I will spell out my case for the hard of thinking: "GRP helmet shells
are fucking strong, even after a bike falling on it and chucking it at
the ground you can whack it ~100 times with a shovel without
penetrating it."

 

Well pardon fucking me, but I know exactly what point I'm trying to make
TYVM. If you don't get it that's your problem.

The function of a helmet is to fail with impacts, absorbing the energy, in
order that your skull doesn't take the force. Whilst your whacking it with a
shovel may only produce minor damage, each time you smack it with a shovel,
that energy has to go *somewhere*, and it is absorbed by part of the
structure failing. The damage *is* cumulative.

Granted I have certainly carried on wearing a helmet after dropping it, as
the perceived risk was less important to me than £200 for a new helmet, but
the mentality that you can treat your helmet like crap every day and it will
still be as strong as one that has suffered no abuse is just plain wrong.

Good for you. I'm saying that if you whack your helmet with a shovel 100
times, it will not survive an impact that a virgin helmet would. Is that
"hard of thinking" proof enough for you?

 

40mph/2m - fatal? I hope not, or I'm dead at least a couple of times
over. Following T-boning the fuckwit in his TNT van, I performed a
"jump, you fucker, jump" manoevre and hit the road some 10m beyond the
point of impact, after clearing the roof of said Fiesta van. My
near-new tri-composite Uvex helmet was trashed by abrasion to the rear
and impact to the front and side, but I had no injury to the head
whatsoever.

I don't think you can hit it hard enough with a shovel, no matter how
strong you are. Your average shovel just doesn't have the mass. A
sledgehammer or pickaxe would be more effective and representative,
perhaps. Helmet-smashing against the clock is a popular game at bike
rallies, where I've seen old lids smashed in one blow by a big lad
with a sledge, when the helmet is mounted on the end of a 4x4 fence
post.

Have a look at this:
http://www.perg.bham.ac.uk/pdf/motorcycle_crash_invest.pdf#search="motorcycle helmet failure"

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Pip

I think that's debatable, TBH...

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer As featured in
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Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

OK, I can see your point. No /fresh/ damage - how's that?

 

Who are you calling a wanker?!

;-)

Yep, I can go with that. The point I was trying to make was in the report
Pip posted:

"... GRP- have a lower elastic limit, then the cloth layers delaminate
and/or the fibres fracture".

Hence damage is cumulative.

So saying, "....and that doesn't explain my helmet which has had no repairs
and is still solid as a rock after a shed load of shovel based abuse", is
incorrect. It may *seem* solid, but it won't hold up to a serious impact as
well as a virgin helmet would.

 

So many possibilities, so little time.

--
Krusty
www.MuddyStuff.co.uk
Off-Road Classifieds

'02 MV Senna '03 Tiger 955i '96 Tiger '79 Fantic Hiro 250

 

I thought that just after I posted it

 

Fer ****'s sake, man - any fule kno that not only would a second-hand,
150,000 mile helmet be just as good as new, but it would also be a
devastatingly fast cross-country missile. One would assume that the
same would hold true for a lid that had been repeatedly shovelled.

Anyway, hitting a helmet sat on the ground with a shovel is far from
the most effective way to do damage to it. A large proportion of the
energy of the blow will be transferred to the ground by the helmet
shell. If Toady wants to test it, he should find a post that fits
inside the lid, up against the liner - then hit it.

I've worn lids after drops, and not come unstuck - yet. However, I
wouldn't hang my lid on a bar end and would have to think twice about
re-using it should the bike fall over on top of the helmet with the
bar end striking the liner. That could constitute just the sort of
point damage that could weaken the shell considerably.

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Pip

Better.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer As featured in
Performance Bikes

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha Vmax Honda ST1100 wiv trailer

 

I stand corrected. You are teh l33t...

 

Yeah, I'm not arguing that the helmet I've used to perfom this test
could safely be used again - it took the whole weight of the bike and
must have flexed a bit. (Although it wouldn't suprise me to find it's
still *very* strong even now)

However. That doesn't detract from the fact that helmet shells are
*fucking* strong.

 

Verdigris says...

I just ask my boss for a new one.

 

Although the discussion centres round the failure mechanisms of fibre
reinforced helmet shells, the thing in this paper that screams out to
be said - which has been done by another poster - is to try the
pull-off test: grasp the helmet by the rear and try to roll it
forwards off the head. If you can get the helmet off, even if it is
the latest high-performing composite etc etc, it's useless in a number
of crash scenarios, mostly involving impact with cars.

The other thing that leaps out from this paper is the necessity to do
the chinstrap up TIGHT, and don't have any strap dangling loose.

Perhaps the most important thing to come out of this discussion is the
importance of the chinstrap and how it's used.

 

Kim Bolton wrote

All of which entirely misses the point that the best helmet is one on
which you never have to rely but that is a discussion of a whole
different order.

 

I was trying to trash my old Nolan the other week, before binning it,
by swinging it, with gusto, against the corner of the bench vice. It
took over a dozen blows to breach the skin of the lid.
--
| ___ Salad Dodger
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|_\_____/_| ..82016../..22238.../..31893.
(>|_|_|<) TPPFATUICG#7 DIAABTCOD#9 WG*
|__|_|__| BOTAFOT #70 BOTAFOF #09 PM#5
\ |^| / IbW#0 & KotIbW# BotTOS#6 GP#4
\|^|/ ANORAK#17 IbB#4 YTC#4 two#11
'^' RBR Clues: 27 Pts: 490 Miles:1992

 

What if you gash the helmet with a paperclip?