30 May 2010

Such Stuff as Fear is Made On

Fabrics
When Shakespeare wrote the line "...such stuff as dreams are made on", 'stuff' meant fabric. Indeed, in Danish, 'stof' is just that, fabric.

I've been wondering about these bicycle helmets on the market that are covered in fabric or even leather. Are they more dangerous than other kinds of bike helmets?

I'm sure we can agree that one of the basic, important qualities of a helmet is that it's slippery. If you're a helmet-wearer and your head strikes asphalt - which is never a smooth surface - I'm sure you'd rather have your helmet slide along the asphalt, as opposed to snagging. That wouldn't be very good for your neck.

While cycling is fantastically safe, most serious head injuries are the result of so-called angular or rotational acceleration, which leads to diffuse axonal injury (DAI) and subdural haematoma (SDH). These are the most common causes of brain injury in all traffic accidents.

Minor injuries are usally the result of linear acceleration. A straight-forward impact without any rotation.

Modern bicycle helmets are only tested for linear impacts and have little effect in preventing rotational ones. In the tests they are dropped straight down onto a flat or slightly-rounded surface from a height that is roughly the same as a cyclist's or pedestrian's head. They simulate a speed of about 20 km/h. They are only tested for impact on the top of the helmet, not the sides or front or back. A vertical fall. They aren't tested for an oblique, or angled, fall which is the most common type.

Nor are they tested with a anything that resembles a human body and all the forces that are involved with many kilograms of body attached to a helmet or impact with a car. There are even studies that suggest that risk of rotational injury is higher with a helmet on. In other words, even low-speed lateral forces can be converted to the far more dangerous rotational forces. Wikipedia has lots of links about it, and the Bicycle Helmet Research Foundation has a page.

Anyway, I was wondering if there was any tests or research done on these new fabric-covered helmets but I have been unable to find any evidence that there is. Landing obliquely on asphalt at any speed is like landing on sandpaper. Racing cyclists shave their arms and legs in order to reduce this sandpapery friction and thereby reduce the severity of road rash caused when body hair slides along asphalt.

The same principle applies to ventilation holes on a helmet as well as to fabric on a helmet. Surely the one thing we can all agree on is that a helmet should be slippery. Even if these fabric covers are easily detachable it certainly seems to be an unecessary risk to run - increasing the chance of having your head snagging on asphalt.

In the midst of my checking around, I recieved an article from a reader out of Australian Cyclist - a lycra mag from Down Under.

They expressed much the same concerns about fabric snagging on asphalt and basically dissed the concept.

"...the typical helmet's smooth, sleek surface is not as much for sporty effect as to prevent it from catching from things during a fall. 'They're shiny and smooth so if you fall off an hit the asphalt it doesn't snag. If it snags you can break your neck'. (says Michael Peel, program director for fashion at RMIT University's School of Architecture and Design)

The Yakkay brand from Denmark does not meet Peel's endorsement on these grounds. This company has created covers for BMX-style helmets that look like fashionable hats and is recieving rave reviews around the world. Peel points out that while he likes the look, the cloth covers could snag in a fall. Ultimately that's the key point with helmets. They are worn as a safety device, not a fashion statement. Anything that adds to style but detracts from safety is a step in the wrong direction."


I've even seen helmets on the market covered with leather, which would seem even more risky than fabric. I recall hearing that some 'stylish' helmets produced for the City of New York featured fabric but the city couldn't get them insured so they were dropped.

I've recently learned that a helmet manufacturer, Giro, made a soft-shell helmet that came with a helmet cover. This was in the early 1990's. They were taken off the market because, among other reasons, the higher risk of neck injury and brain injury caused by the snagging of the fabric on the asphalt.


I think that if companies that produce fabric-covered helmets should be required to produced comprehensive evidence from laboratory tests that show without a doubt that they do not increase the already worrying risk of brain injury.


Whilst researching all this I stumbled across a Swedish company called MIPS. They have developed a new kind of helmet that has a thin layer of liquid between the two shell layers designed to reduce the intensity of rotational impacts. The outer shell rotates a bit upon impact. What's interesting about their website and their video, above, is that they're basically saying that existing helmets don't do much for you.

Ever Lazer helmets call rotational injury The Absolute Enemy.

Marketing or fact? Who knows. I'm not in the market for a helmet so it doesn't matter much. But if were a helmet-wearer I'd stick, at the very least, to smooth and shiny plastic outer layer and not many ventilation holes.

More money-hungry producers of fabric-covered helmets:
- Tail-wags

- ABUS
Related: Denmark Promotes Walking Helmets
- Helmets for Motorists
- More Helmets More Motorists - New Design
- Articles on Bicycle Helmets

15 comments:

Lucas Jerzy Portela said...

no, not more dangerous.

They assume to be hats. I like to go out wearing hats, only the hadwind sometimes gives the impression that the hat will fly away.

I'd wear a helmet like this ones! - and a hate helmets to the guts... - but I'd wear them only because they assume they don't exist to protect, but to be charming.

William said...

Actually, to be fair, it should be noted that the dynamic friction of leather on most surfaces is surprisingly low - low enough that there exists leather-bearings out there.
I'm not going to try it out, though.

Mikael said...

but they do assume to 'protect'. i have a brochure from one of the companies that rattles off all the standard fearmongering stats.

they're telling you they'll save your life. which is a bit of a problem.

Frits B said...

Saw a quote this week about a test of 10 A-brand bike helmets and a balaclava, dropped from a high building. The helmets came off all broken or dented, the balaclava suffered no damage at all. Conclusion: wear a balaclava on your bike and you'll be safe. A joke of course (rumored to be about a test facility in Belgium) but demonstrating that (a) bike helmets don't offer much protection in a real accident, and (b) statistics are nowhere without parameters.
And "stof" in Dutch also means fabric, or dust in any form :-).

Philippe said...

A couple of observations :
AFAIK pro cyclists shave their legs because 1/massage with embrocation is easier that way. 2/hair can be a cause of infection in case of raod rash.

Motorcyclists use leather gear for their protection for ages and it's a material that "glide" pretty well on asphalt. And most other fabric are shredded by the friction : Your shirt don't hold long enough to break your arm, does it ?

Mikael said...

leather on my body would be great for sliding on ashphalt (and s&m parties) - but the risk of your head/neck snagging? nah.

Taliesin said...

When I lived in Australia, I used to put a cover over my helmet similar to this. The point of course was that sunburn was a real concern in the Australian summer, and covers like this seemed the easiest, most comfortable way to prevent it around the face, ears and neck.

Now living in the UK, I'm free to use a standard hat.

Adrienne Johnson said...

I figure if a cowboy hat is enough protection for Rodeo riders getting thrown off of 2000 lb bulls that want to stomp them into the ground, my cowboy hat is good enough for me.

Anyway, it does not matter what the helmet is made of. Most people wear them with the strap at the collar bone so that bucket is going to snag on something no matter what.

Busyman said...

Argh! You guys must be right. Especially regarding leather and motor cyclists. Maybe patent leather is the answer? I'm misquoted again in the media or maybe I've just changed my mind, style over safety any day.

Anonymous said...

Lycra mag - LOL!

amoeba said...

I sometimes wear a leather Fedora, especially when it's rainy or very sunny, but not when it's very windy.

It's a standard Fedora, a hat, not a helmet.

Peter said...

The basic Yakkay helmet under the hat does skitter if bashed against the ground as I have tested it but the hat covering also does in fact slightly inhibit this. I have some reservations about what would happen if the hat was wet though.
All this helmet controversy for such a long time has caused me to look into the literature on rotational injury and the news is not that good for sticky helmet wearers. Even the most stringent helmet tests in the world do not test for it and many studies have concluded it is a real danger.
Research on rotation with helmets goes back to WW2 but most people go with their instincts in the face of scientific and medical literature and draw their own conclusions, usually that brain injury is about being directly whacked.
To get a clearer picture it is only necessary to ask someone whos job is sometimes to cause mild brain injury, such as a boxer.
35 years ago I worked for a while with the ex-S.E.Asian boxing champion and happened to ask how one person knocks another out. His answer was very simple. It is not achieved by hitting the skull but by a direct, but not necessarily hard hit, to the side of the jaw. He said you could fing the spot on your own jaw by lightly hitting in different places till you knew by its affect. It seems that only a slight but definite rotation is necessary. Boxers build the muscles of their necks to reduce this. I heard also that in the past a boxer would grow a slight beard and rub grease into it to allow an opponents fist to glance off.
We do not realise how much effort nature goes to to reduce skull rotation. The skin of your head moves and for that matter it may be the ultimate reason we have hair on our heads as hair also causes slipping. Males may have retained hair on their jawlines as added protection against skull rotation.
All the helmet wearing instructions tell you that it must be securely fitted and not move about and all the testing is done for only the effects of direct hits.
This is scary as for many years in Australia foam helmets, which absolutely stick to any masonary surface as I have tested them, were not only legal but required by law. Only a couple of weeks ago I saw one on a rider in front of me in Melbourne.

Karyn Climans said...

I think you have mistaken the nature of the Mothers Against Naked Riding Campaign. Our goal is to simply encourage helmet-wearing. As long as safety helmets are the best way to protect the brain, we will be encouraging kids and adults to wear their safety helmet. http://www.youtube.com/watch?v=kF-FfYKrgGk

amoeba said...

Karyn Climans said...
"...As long as safety helmets are the best way to protect the brain...."

If you had read the science, you would indeed realise that the evidence does not support your claim.

Here is a summary for you.

The evidence is equivocal, that is it does not show clear evidence of a benefit regarding bicycle helmets. It is true that helmets can provide protection in some limited circumstances, but it is also true that helmets make certain injuries more likely to occur, namely rotational injuries and injuries to the neck, which they cannot prevent.

Helmets by their very nature are designed to protect people who fall off their bicycles at low speeds. Helmets are more appropriate for pedestrians, do you wear a helmet when you walk?

Helmets may encourage risky behaviour among some cyclists. There is some evidence that bicycle helmets may make accidents more likely - by encouraging drivers to drive closer to helmet wearers than those who do not. http://drianwalker.com/overtaking/overtakingprobrief.pdf

Helmets send the message that cycling is a risky behaviour, it isn't. Indeed, when taken in the wider context, of the numerous and extensive health benefits of aerobic exercise, cycling is safer than NOT cycling, because of the health benefits of exercise. http://cyclehelmets.org/1015.html

Places where cycling is common-place are places where helmets are unusual to rare. This is no coincidence, places where cycling is commonplace where the environment for cycling is safe. Motor-vehicles are the primary danger to cyclists. The greatest way to protect cyclists is to protect them from motor vehicles. Helmets are not designed to deflect motor-vehicles and cannot do so. Pieces of sweaty, uncomfortable plastic worn on the heads of cyclists can play no significant part in this.

Links to the science:
http://www.cyclehelmets.org/1157.html

index.php said...

What about helmet lights. You don't even need to hit the road for them to get snagged - a low hanging tree branch will do.