Helmet design features

General cycling advice ( NOT technical ! )
tim-b
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Re: Helmet design features

Postby tim-b » 25 Aug 2019, 7:37am

Hi
I suggest that this thread stays on topic, i.e. design features, rather than causing what could be useful/interesting to disappear into that sub-forum.
If you want to argue about inconclusive studies and stats then please head :roll: there
Regards
tim-b
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gxaustin
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Re: Helmet design features

Postby gxaustin » 25 Aug 2019, 8:38am

A lot more credible than claiming cycle helmets are as light as ordinary hats!


Ha ha -you win. So you have a top hat and a trilby that are lighter than my beret.
The rest is opinion and you are welcome to it.
If you want to argue about inconclusive studies and stats then please head :roll: there

Sorry about that - I don't. I merely dispute that helmet wearing causes neck ache. The end.

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Wanlock Dod
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Re: Helmet design features

Postby Wanlock Dod » 25 Aug 2019, 9:39am

gxaustin wrote:... I merely dispute that helmet wearing causes neck ache...

Apparently not so uncommon for those that don’t usually wear helmets, I find it usually starts after about 100 km along with some possible risk compensation. I would imagine that it doesn’t take much routine helmet wearing to develop sufficient extra strength in the neck for it not to be an issue.

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Cunobelin
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Re: Helmet design features

Postby Cunobelin » 25 Aug 2019, 9:51am

Tangled Metal wrote:I've been looking at helmet wearers on my recent Belgium tour and wondered what is the significance of certain helmet features. Anyone know?

The round shape of helmet.
The large often vertical vents at the rear sun a kind of top lip or spoiler. Often found on kask brand I think.
Large slot at the front which isn't on all highly vented helmets.

I'm sure there's more. It's probably just brand design, gimmicks or marketing but is there any tangible design / performance reason for certain design features. Do they play into suitability for certain uses?

Please ignore the actual helmet debate side of things or I won't get any answers to my query.



I will try and stay on the right side of "the line'

Firstly there is evidence that in an impact some energy is dissipated by the helmet sliding along the surface of the road, so a round shape facilitates this. Secondly, there is evidence that the sharp angles and edges of vents can "snag" on the road surface. This decelerates the helmet quicker, imparting more energy to the brain. it can also cause rotational elements.

This is one of the reasons in the US for the "Rounder, Smoother, Safer" campaign


Then we come to vents and will leave aside the snag points addressed above.

In theory helmet functions by absorbing energy through a material.

As more vents are used and larger ones, there is less absorbent material and the helmet is less able to absorb energy so less efficient.

This is then exacerbated by the fact that in order to maintain integrity the remaining material has to be stiffer and denser to maintain the structural integrity, again decreasing the ability to absorb the energy of an impact. Oven with a structural cage within the design, the energy absorption is decreased by modern helmet design.

Then, we have the latest "fashions", with MIPS and similar. All have their pros and cons and are yet unproven. In fact, MIPS is a classic example, where the Snell laboratories have shown no additional benefit, and that is being contested by the MIPS designers. There are also some reports where the MIPS liner has caused injury

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freiston
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Re: Helmet design features

Postby freiston » 25 Aug 2019, 2:04pm

I just weighed some hats:

Waxed cotton wide brimmed hat - 126g

Legionnaire style baseball cap - 67g

Synthetic Altura cycling cap - 35g

Specialized Max cycle helmet - 405g

I used to wear trilby style hats of felt and of heavier cloths though don't have any now but IME, the waxed cotton hat is similar in weight.
Disclaimer: Treat what I say with caution and if possible, wait for someone with more knowledge and experience to contribute. ;)

gregoryoftours
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Re: Helmet design features

Postby gregoryoftours » 26 Aug 2019, 7:14pm

Peaks on MTB helmets - more upright riding position means it doesn't interfere with vision as it can with the head down position on a road bike. It reduces sun glare and also provides more protection from twigs/branches slapping you in the face/eyes.

A cycling bandana under a helmet protects from sun through the vents, and including back of the neck, absorbs sweat and prevents that horrible feeling putting a cold wet helmet back on, and keeps you a little warmer in winter.

Vorpal
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Re: Helmet design features

Postby Vorpal » 27 Aug 2019, 8:56am

I am about to embark on my annual must-wear-a-helmet ride. I bought a new helmet last year because the plastic structure that held my old one onto my head had broken. I spent a fair amount of money. One might think that it doesn't really matter, and if a cheap helmet had fit me, I would have bought at cheap helmet. But I must have tried on 50 or more helmets in 3 different shops before I found one that I thought I could wear for more than 15 minutes.

Anyway, my primary criteria is that it fits well, and will sit correctly without being uncomfortable. That usually gives me a pretty limited (and unfortunately expensive) selection of helmets to choose from. After that, I will go for ease of adjusting & clipping, cost, weight, appearance, and whatever other differences there might be between helmets that fit me.

I suspect that the rounder, unbroken shapes such as kask may be less inclined to snag, and more beneficial in crashes that result in sliding, but that style of helmet does not fit me at all, and in shape/roundness there is seldom much difference in the helmets that do fit me.
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Cunobelin
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Re: Helmet design features

Postby Cunobelin » 27 Aug 2019, 6:44pm

Vorpal wrote:I am about to embark on my annual must-wear-a-helmet ride. I bought a new helmet last year because the plastic structure that held my old one onto my head had broken. I spent a fair amount of money. One might think that it doesn't really matter, and if a cheap helmet had fit me, I would have bought at cheap helmet. But I must have tried on 50 or more helmets in 3 different shops before I found one that I thought I could wear for more than 15 minutes.

Anyway, my primary criteria is that it fits well, and will sit correctly without being uncomfortable. That usually gives me a pretty limited (and unfortunately expensive) selection of helmets to choose from. After that, I will go for ease of adjusting & clipping, cost, weight, appearance, and whatever other differences there might be between helmets that fit me.

I suspect that the rounder, unbroken shapes such as kask may be less inclined to snag, and more beneficial in crashes that result in sliding, but that style of helmet does not fit me at all, and in shape/roundness there is seldom much difference in the helmets that do fit me.


These "must wear a helmet" rides are a prime example of the stupidity and lack of knowledge that "informs" many helmet decisions
decisions.

UK Cycling Events is a classic. For many years they insisted on Snell or ANSI standard helmets, excluding the EN1078 that allows sale in the UK. In theory, turn up with an EN1078 helmet without the additional testing and they would disqualify you. Also note the irony (I will explain later) of ANSI Z90/4 being the "Latest"

Their website used to state:

It is mandatory that all riders wear a safety-approved cycling helmet complying with latest ANSI Z90/4 or SNELL standards. Any rider not wearing a helmet will not be covered by the event insurance and will be disqualified from the event and could be liable for damages if involved in an accident on that basis. The rider must accept this as a condition of entry.





They eventually changed this and the current regulations state;

You must wear a safety-approved cycling helmet complying with latest EN1078, ANSI Z90/4 or SNELL standards during your participation in the event. Any rider not wearing a helmet will not be covered by the event insurance and will be disqualified from the event and could be liable for damages if involved in an accident on that basis. You must accept this as a condition of entry.


I have highlighted the ANSI Z90/4 for a reason.

Note how they demand the "latest" ANSI Z90/4... There is a small problem!

ANSI As a helmet authority in the US no longer exists, the ANSI committee has not sat since 1995, yep - they have not existed for 24 years!

ASTM superseded ANSI and as a result, no helmet has passed ANSI since that time the "latest" ANSI Z90/4 is 1995.

These image shows the type of helmet that carries ANSI Z90/4 certification:

Image

Image

They are demanding cyclists use a 24-year old helmet.

It illustrates clearly and unequivocally an ignorance of cycle helmets, their design, and testing standards

rmurphy195
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Re: Helmet design features

Postby rmurphy195 » 27 Aug 2019, 10:34pm

I suspect the round shape of helmets - whether cycle, motorcycle, or car - has as much to do with reducing the risk of irregular edges catching on something as you are sliding along. F1 helmets excepted of course, wear the driver is pretty well cocooned, and where the helmet becomes part of the earodynamics.
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