xorl %eax, %eax

Motorcycle Helmets

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So, this is my two cents on this truly crucial subject which is in fact, a matter of life or death in some cases. I will attempt to provide information from design technical issues to practical information that every rider should be aware of. Before diving into the details, here is a quick list of the most common helmet types used today.

Helmet Types
The most popular helmet type is the full face like the Shoei RF-1100 shown below.



The motocross ones like this Fox V3



Of course, the half-helmets such as the Harley-Davidson Destination one



And the modular which are very popular among on-off bike riders. An example is the Airoh Mathisse RS you can see here:



Personally, I always suggest using a full face helmet regardless of your riding style or bike. There are quite a few reasons for this. First of all, in case of an accident is the only helmet type that protects the rider’s head from almost any possible angle. The modular helmets can do this too but it is risky since it is more likely to break the front cover of the helmet and leave your head partially exposed. Additionally, in everyday riding a full face helmet can protect you from anything that might found floating in the air. Especially in Greece this is a very common scenario which includes anything from cigarettes, trash, gravel to plastic cups, bottles and basically anything you can imagine. Furthermore, it’s by far the most comfortable when riding with strong wind, rain or simply in high speeds. Now that I have expressed my opinion I can move on. :P

Motorcycle Helmets Parts
So, the helmets are constructed in different parts. Here is a quick list moving from the outside to the inside.

Visor



Visors do not break and they are designed to absorb impacts by transferring it to the helmet’s outer shell. Additionally, they usually have UV protection and can also be found tinted in various colors (like the Arai dark visor shown in the picture above). This prevents the rider from wearing sunglasses that could result in serious injuries in case of an accident. Also, most high quality vendors provide visors with perfect sealing against incoming air and pinlock/anti-fog support (either as an additional attachment or by design). It might look like an unimportant plastic piece but in fact it has numerous unique features including the ability to have clear view without any reflexions, not losing its flexibility throughout time and environmental changes, etc. Nowadays, most visors are constructed using polycarbonate which can have all of the described features.
It is important to note here that the past few years the most popular brand, Arai Helmets provide helmets with 5mm (on each side) wider visors which might sound insignificant but in reality it makes great difference.

Air Flow/Exhaust System
A common feature in modern helmets is air flow control using exhaust systems and spoilers.



Most people think that this is important only in high speeds when the helmets starts vibrating hard because of the incoming air. However, a well designed air flow system will keep your head cool in hot days and make your helmet stable since the main problem arises at the back of the helmet where the air creates a turbulence due to lower pressure. The exhaust systems resolves this and also provide great noise reduction. Most high quality helmets also provide adjustable spoilers (which makes difference in high speeds) and air flow inputs (that you can use to have the same helmet in both cold and hot days by adjusting them).

Outer Shell
This is usually constructed by hard materials such as kevlar, fiber and thermoplastics.

This is the main protection against an impact and it has two roles. The first is to prevent any object from penetrating the helmet and the second, and most important, is to provide a uniform, equally distributed absorption of the impact’s energy. Additionally, based on statistics, helmet vendors reinforce the areas which are more likely to get hit in an accident. Since the outer shell apart from special design concepts of each brand is based on the construction material, I will provide a quick overview of the most common classes which are separated in low price helmets (usually thermoplastics) and expensive ones that use composite materials.
Outer Shell – Low Price Helmets
The most common thermoplastics used in motorcycle helmet industry are lexan and polycarbonate. All of the thermoplastic outer shells have some common properties. The advantages include the low price, the material flexibility which in reality means that you won’t have to buy a new helmet if yours gets a small impact and they usually don’t require any special maintenance. On the downside, with average and high speeds they aren’t the ideal option. The most common disadvantage is their limited lifetime (roughly 5 years) and the material’s temperature specific properties. For example, if a rider finds him/herself sliding on the road after an accident, the thermoplastic shell will reach high temperature that will alter its designed friction factor (it should normally slide on the road without any resistance to avoid neck injuries).
Outer Shell – Expensive Helmets
First of all, they are more expensive basically for two reasons. The first is the extensive work that has to be performed on composite materials such as carbon and kevlar which are among the two most widely used materials in such helmets. Secondly, is that most of these helmets are handmade. Now, on the upside, officially they can last forever, however it’s good practice changing your helmet after 10 years or so. The epoxy used in such materials can provide the required hardness and the fibers can have excellent energy distribution. Additionally, these materials have low to none dependence on environmental changes. In the scenario of sliding given earlier, a composite material helmet won’t increase its temperature and consequently, it will not affect its friction. The main disadvantages are their high price and that minor impacts can damage the outer epoxy layer and/or fibers and thus making the helmet useless. That said, you should always replace a composite material helmet even after a very minor damage.

Protection Layer
This layer is commonly constructed using polystyrene and it’s used for absorbing as much energy of the impact as possible.



This is a flexible material that can absorb great amount of energy. To do this, a thick layer of polystyrene is inserted under the outer shell of the helmet. Of course, depending on the design this might increase the helmet’s weight. Apart from the important role as a protection layer that absorbs energy, it also provides thermal insulation and noise reduction.

Retention System
Most helmets use the so-called double-D ring strap which looks like this:



This is fine for everyone although you must get used to it to feel comfortable. In addition, double-D ring strap has passed all the safety tests by all organizations so far. Another popular strap is the following buckle which is known as micrometric:



This is easier to use but it might result in injuries if it’s constructed by some hard materials. No matter what the retention system is on your helmet, remember that an unfastened helmet is most of the times more dangerous than not wearing one at all. Apart from the obvious case of being hit and getting of your head living you unprotected, there is an even worse case of for example hitting the chin spoiler and basically raising the front part of the helmet and thus hitting the back of your neck with your own helmet. Remember to always fasten your helmet so that it cannot move.

Interior Padding
This is basically for rider’s comfort.



This property is derived by three factors, the noise reduction, comfort but secure fitting on rider’s head and absorb of vibration. In any high quality helmet all of the padding is easily removable for washing but I’ll discuss this later in this blog post. Furthermore, you should check that your interior padding is constructed with materials that will let your skin breath, they don’t block the air flow, they are anti-sweat, anti-bacterial and that the chick pads are tight enough to always keep the helmet on its place.

Fitting and Sizing
The helmet must be tight. In the ideal case, you should not be able to move your helmet in any direction without moving your head as well. You can check this like this…
1) Put on your helmet and fasten it (always)
2) Now place both hands to hold each side somewhere over your ears
3) Try to move your head right, left, up and down without moving your hands
If you have the correct size you should not be able to do this without stretching the skin of your head. One common complain among new riders is that chick pads are tight. They must be tight but not extremely tight. Like the rest of the helmet they should be in full contact with your skin. Some brands provide helmets for different types of heads so if your helmet doesn’t fit right it might be because it wasn’t designed for you. Always check your ability to move and breath before buying it. Go to a shop, put it on and keep it on for a few minutes (3-5), you’ll most likely notice its pros and cons. If you are wearing glasses, check that there is enough space inside the interior padding to wear your glasses. By the way, always wear your glasses after you have put on your helmet, if you can put on your helmet with your glasses on, it’s probably of incorrect size (this is for full face only).
Now let’s move to the sizing. Here is a diagram that pretty much says it all…

If for some (almost impossible) reason you cannot measure your head as shown above, there is another accepted method among most riders. This is, wear a few helmets until you find the one that you believe is your right size. Now, take one size smaller and that’s probably the right one.

Maintenance
Although there are ready to use cleaning products, there are simple ways to clean your own helmet without buying any additional products. First take apart your helmet, this means removing the visor and the (hopefully) removable interior padding. Next fill a container with some warm water and some shampoo with neutral pH like most of the baby shampoos. Use this to wash the interior padding parts. Now for the outer shell, if you don’t want to use some official cleaning product, please use only water. The chemicals of other cleaning products can damage the internal structure of the helmet’s materials and consequently affecting its hardness or flexibility. Same applies for the visor. Warning, after you have cleaned your helmet don’t use a hair dryer to dry the remaining water. The increased temperature can damage the helmet. You should let it dry in normal conditions (possibly in a shady place during a hot day). This makes summer the ideal season for such tasks. Don’t forget to apply the provided (with all helmet’s I know of) sealing silicon between the visor and the helmet before using it.

Common Mistakes
Putting stickers on your helmet. This could make your helmet useless since the solvents used in some stickers’ glues are reacting with the thermoplastics (this doesn’t affect composite material helmets) of your helmet by changing their properties. Vendors that sell helmets with stickers use solvents designed to keep the outer shell’s composition intact. The same applies to painting your helmet as well but this time it also affects composite material that have multiple layers of protection materials. Another common mistake is not changing your helmet after some years which is about 5 for thermoplastic and 10 for composite material ones. Finally, one of the most common I encounter almost on a daily basis is about expensive carbon and kevlar (and other composite material) helmet owners that even though they have damaged their helmets, they’re still using them. Composite material helmets are not safe to use after even a minor damage due to their construction materials.

Before ending up this post, please always remember. It doesn’t matter how much you will pay for your helmet because after all you can always buy a new one but you cannot buy a new head. ;)

All of the above pictures are taken from Google Images and the idea of the post was from an article I had read on a Greek magazine a few years ago. Unfortunately, I cannot recall the magazine to reference it properly. If you do, feel free to do so. :)

Written by xorl

March 13, 2011 at 00:32

Posted in motorcycles & cars

7 Responses

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  1. What’s the best visor to get if you don’t want to carry two helmets with you but do both day and night riding?

    anonymous

    March 13, 2011 at 00:39

  2. If you want to have two visors, depending on your helmet model you can have a clear one (usually the one that comes with the helmet) and a dark tinted with UV protection.

    xorl

    March 13, 2011 at 00:47

  3. can you get helmets with built in speakers and ipod plug in

    motorbike helmets

    June 19, 2011 at 02:06

  4. I haven’t seen anything with this feature but I guess that there might be

    xorl

    June 30, 2011 at 18:10

  5. very good information, i keep seeing a lot of the younger riders wearing them on mopeds.

    Arai

    July 5, 2011 at 10:50

  6. There is definately a great deal to find out about this topic. I like all the points you made.

    custom motorcycle helmets

    March 5, 2012 at 12:12

  7. Great post and I agree that wearing a motorcycle helmet can be one of the deciding factors of injuries during a motorcycle accident. I like how you point out some weaknesses in modular helmets but I also agree they are better than nothing! Thanks again.

    Thomas

    May 27, 2013 at 08:28


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