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Helmet outer casing has degraded in only 3 years

Posted: 12 Oct 2020, 11:12am
by Pebble
Out of all the plastics in the worlds that are near impossible to degrade, this manufacturer has found one that starts to disintegrate after about 3 years, its turning a yellowy shade and has become stupidly brittle. What an utter waste!
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Re: Great Helmet Design

Posted: 12 Oct 2020, 11:16am
by peetee
Seems to have happened more on one side. Do you leave it by a sunny window?

Re: Great Helmet Design

Posted: 12 Oct 2020, 11:56am
by Pebble
peetee wrote:Seems to have happened more on one side. Do you leave it by a sunny window?

opposite of POSH, I ride North in the mornings, shelter in the mid day sun and return in the evenings :D

seriously though that seems to be a camera affect it all has a yellowish tinge

Re: Great Helmet Design

Posted: 12 Oct 2020, 12:32pm
by foxyrider
Given that the advice is to change helmets due to degradation every 3 years maybe its intentional to get you to follow the advice - inbuilt safety obsolescance?

Have to say, its the first time i've seen that without there having been an impact incident.

Re: Great Helmet Design

Posted: 12 Oct 2020, 12:53pm
by Mike Sales
One wonders how strong this helmet was before the decay was apparent.
Do any of the various helmet standards have any stipulations on longevity?

Re: Great Helmet Design

Posted: 12 Oct 2020, 1:54pm
by Pebble
I can't imagine that very thin plastic layer having any function other than decorative to be honest. Is it supposed to be part of the structural integrity? may be it just stop the sun degrading the polystyrene bit?

Re: Great Helmet Design

Posted: 12 Oct 2020, 2:08pm
by al_yrpal
My 10 quid Aldi job is still perfect after 6 years. Never been bashed

Al

Re: Great Helmet Design

Posted: 12 Oct 2020, 2:13pm
by tatanab
Pebble wrote:I can't imagine that very thin plastic layer having any function other than decorative to be honest. Is it supposed to be part of the structural integrity? may be it just stop the sun degrading the polystyrene bit?
Agreed. If people remember the early helmets from the late 70s to mid 80s, the vast majority were simple polystyrene shells and you used a sort of elastic mesh decorative outer sleeve with it. Manufacturers were perfectly candid and owned up that the purpose of this was to hold the polystyrene in place as it collapsed/disintegrated in event of an impact.

Re: Great Helmet Design

Posted: 12 Oct 2020, 2:51pm
by mjr
al_yrpal wrote:My 10 quid Aldi job is still perfect after 6 years.

How do you know? Might shatter on first impact and I bet it's no longer under even limited guarantee.

I don't understand the mentality of helmet users who ignore the instructions. Worse than not using.

Re: Great Helmet Design

Posted: 12 Oct 2020, 3:01pm
by Mike Sales
Pebble wrote:I can't imagine that very thin plastic layer having any function other than decorative to be honest. Is it supposed to be part of the structural integrity? may be it just stop the sun degrading the polystyrene bit?


All plastics suffer UV degradation, don't they? If the protection for the foam has gone it cannot be good.

Re: Great Helmet Design

Posted: 12 Oct 2020, 3:10pm
by Bonefishblues
Mike Sales wrote:
Pebble wrote:I can't imagine that very thin plastic layer having any function other than decorative to be honest. Is it supposed to be part of the structural integrity? may be it just stop the sun degrading the polystyrene bit?


All plastics suffer UV degradation, don't they? If the protection for the foam has gone it cannot be good.

I think Pebble's right - on mine it's not even attached to the foam layer except by some kind of tape around the perimeter (and this one looks similar), so it's adding nothing, structurally that I can see.

(Or have I misunderstood - do you mean that the foam will now be unshielded, and may now degrade itself?)

Re: Great Helmet Design

Posted: 12 Oct 2020, 3:11pm
by Mike Sales
Bonefishblues wrote:
(Or have I misunderstood - do you mean that the foam will now be unshielded, and may now degrade itself?)


That is what I meant.

Re: Great Helmet Design

Posted: 12 Oct 2020, 3:29pm
by Pebble
mjr wrote:
al_yrpal wrote:My 10 quid Aldi job is still perfect after 6 years.

How do you know? Might shatter on first impact and I bet it's no longer under even limited guarantee.

I don't understand the mentality of helmet users who ignore the instructions. Worse than not using.

are they only deigned and tested up to 14mph or something ?
if so then they are already not much use at the speeds I'm glad to be wearing a helmet at.

Re: Great Helmet Design

Posted: 12 Oct 2020, 4:13pm
by mjr
Pebble wrote:
mjr wrote:I don't understand the mentality of helmet users who ignore the instructions. Worse than not using.

are they only deigned and tested up to 14mph or something ?
if so then they are already not much use at the speeds I'm glad to be wearing a helmet at.

I thought it was 12mph, but something like that.

I don't see why you're glad using one at higher speeds: helmets are primarily for low-speed falls onto the top of your head. If it's making you feel more confident cycling at higher speeds, then you are probably experiencing risk compensation and increasing the danger to the rest of your body if not also your head.

Re: Great Helmet Design

Posted: 12 Oct 2020, 5:49pm
by Brucey
foxyrider wrote:.. its the first time i've seen that without there having been an impact incident.


there clearly have been multiple impacts; the dents in the polystyrene are witness to that.

FWIW the OP's helmet is ready for the bin; the usual idea is that the microshell holds the (broken) pieces of polystyrene together for long enough to do some good in the event of multiple impacts. Once the microshell is brittle it won't do that any more.

Some helmets have an internal web moulded into the polystyrene which does the same job (and better) but you can't see that there is one or not until the helmet is properly broken.

cheers