It is indisputable that in addition to the characteristics of resistance and absorption of kinetic energy, in the event of a collision, weight is an important and qualifying feature of the helmet.
A light (and resistant) helmet, in addition to making the driver less fatigued, has the advantage of not overloading the rider's head area, reducing fatigue which over time leads to a reduction in attention to driving, with a consequent reduction in safety.
A light (and resistant) helmet has the advantage of reducing the kinetic energy in the event of a collision. In fact it is important to limit the weight of the helmet as much as possible in order not to increase the energy that it must absorb due to its own weight. Greater weight of the helmet means possible greater energy to be dissipated in the event of an impact in fact: Kinetic Energy Ec = m · v² / 2 (mass x velocity squared: 2 )
It is useless for the helmet to withstand even the impact of energy derived from its own weight. Therefore, given the quality level, it is important to choose a lightweight helmet with the same characteristics.
The concept of a noise level in motorcycle helmets is variable and lends itself to many interpretations. A biker can be comfortable with a certain level of noise, feeling safe hearing outside noise, while another prefers to be "muted".
The shape of the helmet influences, even if relatively, the internal noise. Naturally a more aerodynamic shape favors noiseless. In particular, the rear shape of the helmet positively or negatively influences the turbulences, that increase noise. The accessories, however greatly affect the perceived noise level, as air-system air, some visor attachments, some spoilers, break the flow and increase the perceived noise level.
In addition to the shape of the helmet, the noise inside the helmet is particularly influenced by the position of the driver, by the conveyed air flows, by the windscreen or front fairing or by the front shape of the motorcycle.
Silent helmets with one type of motorcycle become very noisy with another.
However, it should be evaluated: Does the helmet have to "muffle" the motorcyclist or for safety must make the external noises be perceived?
It would be easy and inexpensive to decrease the internal noise level in the helmet, it is sufficient to increase the foamy "mousse" at ear level, and the motorcyclist would be "deaf" and would not perceive the noise of the helmet, nor the external noises. And security??
Cast helmets have been designed with this issue in mind, placing safety first, which is why the inside of the ears is not heavily foamed.
It must be said, that the helmet is also chosen depending on its use.
In fact a city use implies for the safety, the use of a helmet, which foresees the possibility of hearing the external noises.
Helmets fundamentally designed for professional or sports / technical use, given the higher intensity of noise in the field, they can be "silenced", even if, it is up to the rider to decide the level of noise perception, by choosing the type of helmet.
Considering that a helmet, which has suffered an impact, must be replaced even if it does not have obvious breakages externally, as the inner EPS shell can be damaged. The helmet life is influenced by the kind of use, but it is possible to give prudential indications.
For a plastic helmet, considering the rapid aging of the resin, it is recommended to use it for no more than 3/4 years. It should be considered that the high temperatures or the petrol fumes affect its resistance, and the helmet in this case must be changed.
The fiber helmet given the lower aging, remains usable for at least 6/8 years. The fiber shell does not undergo alterations even for a much longer time, but the other internal parts of the helmet will undergo aging.
However, consider that the helmet ages even inside the shop window or in the warehouse. For this reason, do not be attracted by offers of "centenary" helmets, you can legally use them, it is not mandatory to enter the production date.
For your safety is always better to have a less “dated” helmet.
When buying a helmet, first check that it is properly homologated by reading the approval label, which is present sewn on the helmet strap.
In order to be used, the helmet you purchase must be approved with the specific European ECE 22.05 approval, while helmets with other homologations cannot circulate in Europe.
ECE approval requires that before being able to sell a type of helmet, tests are performed in a certified laboratory, at the presence of an official of the Ministry of Transport. Tests are made on a pre series of 50 pieces, in order to certify that the project meets the technical and resistance specifications according to the ECE 22.05 standard. The approval number identifying the helmet is obtained with a positive result.
Afterwards the certified laboratory will test the samples of each production lot, only with positive results labels will be delivered. You can assure yourself that the helmet you are buying is in "rule" from what is reported on the label sewn on the strap.
On the label sewn on the strap, in a circle you find an E with a number that corresponds to the country where the helmet was approved (E1 = Germany E2 = France E3 = Italy E4 = Holland)
This is the list of countries and the corresponding approval label:
Then find a series of numbers
A letter specifies the type of protection for which the helmet has been approved.
Before buying a helmet we must ALWAYS check the presence and completeness of the homologation label. This will let you know more about the protection device we are buying, and will allow us to use it to the fullest.
DOT stands for Department of Transportation and the standard is the FMVSS 218 standard, (Federal Motor Vehicle Safety standard # 218). It is used for helmets sold in the United States. While for the ECE, before being able to put on sale a type of helmet, tests are performed on a pre series in order to certify that the project meets the specifications of the legislation. With the DOT, each helmet manufacturer independently certifies the compliance of the helmets of its production with the FMVSS 218 standard. It consequently applies the DOT mark before being put on the market.
SNELL (Snell Memorial Foundation )
The Snell Memorial Foundation is a private, non-profit organization established in 1957 with the aim of improving helmet safety. The Snell certification is voluntary and is not requested by European or international authorities. It has no legal value, but evaluates who excels in protection through their own helmets.
To obtain SNELL certification, the helmet must pass the standardized tests by the Foundation. Positive peculiarity of the tests required is the random impact, and not on predetermined points as in the homologation tests. After passing the test, the helmet can be labelled with the SNELL brand.
Sample checks are carried out afterwards, in order to verify the compliance of the specifications and the modification of the helmet.
Established in 2007, the SHARP agency is a British government emanation of the Ministry of Transport. Given that the helmets on the market exceed the current ECE Regulations, SHARP aims to assess how the various helmets exceed the performance required by the standard.
All helmets to be tested are not supplied by the manufacturers, but taken directly from the shops, and this makes it more transparent evaluation. Tests are stricter than those required by the ECE procedure, in fact the test involves a test at a higher speed than both the ECE procedure and the SNELL one.
The result is a classification from one to five stars for each helmet, where one star is the minimum and five is the maximum performance. This system makes this test as well as reliable and immediately understandable.
The information provided is in good faith based on our knowledge and public data. We are not responsible for inaccuracies.
Stating that, helmets for professional and sports pilots, due to the required safety features and the regulations in force, can only be Composite Fiber products, as well as car helmets.
Motorcycle helmets purchased by a motorcyclist are instead produced with two distinct and different families of materials.
Thermoplastic materials, Polycarbonate, ABS, or other thermoplastic resins and Composite fibers impregnated with thermosetting resins.
Thermoplastic and composite shells production
they are materials that can be easily used in the production of helmets with economic and automated systems. The ABS, polycarbonate or other thermoplastic materials shell molding are easy to perform and the daily productivity is very high, so this production system is particularly ideal for large-scale production with economies of scale. The production method consists of putting a thermoplastic granule in a press, that injects it into a mold after melting it. After cooling, the shell is practically finished in every detail and can be painted or can be used with the mass colouration.
The cycle lasts on average 1 minute, so the production normally exceeds the 50 shells per hour. The whole cycle is generally robotized and does not require operators with specific specializations for production.
they are characterized by a manufacturing method that is difficult to automate and with slow and complex production cycles.
For this reason, depending on the required level of quality, the production process is much more expensive than the previous one. It also requires specialized personnel for quality production, and in general a production time that is tens of times slower than that of thermoplastics.
The method of production, largely manual, consists in arranging manually "patches", with predetermined dimensions, of fibers fabrics (glass, carbon, Aramid), with method and alignment prior designed in or on all sides of a mold.
The resin in the liquid state is sprayed into the mold in the predetermined quantity, then a balloon with the shape of the helmet is inflated inside the mold in pressure, in order to make the resin between the fibers well permeate evenly over the entire surface and let out any trapped air.
The resin is polymerized by cross-linking in the heated mold and the shell is almost ready.
Further treatments are needed: cutting edges and windows, eliminating burrs, drilling aerations, etc. Then on the row shell, grouting, sanding, priming and final painting. All manual treatments that require time and good experience. Of course the type of fibers used and the experience of the operator gives the quality level of the helmet.
Considering what we have written above, it is clear that the difference in production costs between the materials is considerable, but the difference in behaviour of the helmets produced with the two technologies is also notable.
it has a remarkable elastic return and by not absorbing energy in the event of a collision, the considerable elastic return leads to the transmission to the spine of most of the kinetic energy derived from the impact, causing trauma to the spine. Compared to the composite fiber helmet it has a lower mechanical strength and a lower rigidity, so it requires, for the same load, greater thicknesses and therefore greater weight.
Once a fracture has started in the shell, it advances fairly easily, a typical disadvantage of thermoplastics. That is, a small break generally causes a complete and immediate destruction of the helmet. Furthermore, thermoplastic resins age very quickly compared to thermosetting resins especially with heat and due to the effect of sunlight, not the least of which is the reduction of resistance to cold.
Important! petrol vapours deteriorate significantly the Polycarbonate, so it is recommended not to leave the helmet on the tank. Due to its structure, therefore, the thermoplastic material has weak points: low rigidity, premature aging, low impact resistance, low resistance to cold and petrol.
Of course the big positive factor of the thermoplastic helmet is the low production cost, even if you have to replace the plastic helmet no later than 3/4 years.
Therefore, for cost-effectiveness and industrial production in large lots, the Thermoplastic Resin helmet is suitable for economical helmets for city use, where speed and possible high impacts are not at stake.
in the event of a collision, it suffers a rupture of the structure and of the fibers proportional to the impact, at the same time it absorbs a good part of kinetic energy, which is not transmitted to the backbone of the motorcyclist. The presence of the fibers leads to a considerable increase, both in the breaking load and in the rigidity, which allows to use reduced thicknesses and weights for the same resistance. Due to the arrangement of the fibers and the characteristics of the materials, breakage progress is effectively hindered. In fact, a fiber helmet gradually breaks down while the plastic one disintegrates. The fiber helmet also maintains its characteristics for a long time without appreciably aging.
It must be said, however, that the "Fiber" helmets can be of different qualities and strengths. In fact, normal glass fiber is the most economical and least resistant as well as heavier, the weight / strength ratio is extremely disadvantageous compared to other fibers.
An economic and low-performance fiber helmet occurs from the “high” weight. The Multiaxial fibers possibly reinforced with Carbon or Aramid notably increase this ratio, so we have helmets lighter and more resistant.
The maximum of this weight / resistance ratio is obtained by using Carbon Fibers impregnated with epoxy resins, currently the best high-tech material that the industry is able to produce in appreciable quantities. A carbon fiber is a long thin wire largely composed of carbon atoms. Several thousands of carbon fibers are twisted together to form a fabric with a very high tensile strength. To give an idea, the tensile modulus or the resistance that it can withstand without breaking is over 140 M.psi for more resistant and quality fibers.
For comparison, steel has a modulus resistance of about 29 M.psi, so the best carbon fiber is about five times stronger than steel (and lighter).
However, this is paid for with a greater complexity of the production process and consequently an increase in the relative costs.
Furthermore, being a manual production, the quality of the shell and consequently its resistance is in the operator's "hands".
In fact, the Carbon Fiber helmet must be produced by experienced and specialized personnel, as production must take place with strict parameters and perfect fiber disposition so as not to compromise the advantages deriving from the use of this fiber.