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Motorcycle armor comes in a variety of forms, from traditional yellow foam to high-tech compounds capable of absorbing large amounts of energy. In its basic form an armored jacket will include shoulder and elbow armor. Trousers will include hip and knee protection.
Types of armour
This armour is the typical yellow foam similar to the foam you might find in a mattress. For its thickness, it offers a relatively low level of protection.
Memory foam armor achieves the highest levels of absorption to thickness. It is a very dense foam.
Hard armour usually consists of a hard plastic backing with foam laminated to the inside.
Strain rate sensitive armour
The use of highly viscoelastic materials in motorcycle armour has allowed for elbow, knee, shoulder and back armor to be manufactured in a soft and pliable state at rest. Upon the introduction of shock the armour changes at the molecular level and adopts extremely rigid and protective properties. Examples of this armour are SAS-TEC, d3o, Rukka APS air, EXO-TEC and TF armor. They are currently being used in pinnacle jackets, trousers and suits by manufacturers such as REV'IT!, Firstgear, BMW Apparel, Scorpion, Rukka and Aerostich respectively.
Whilst such systems have been shown to achieve similar performance to traditional foam and hard armour solutions, perceived benefits of molecular armor systems above more established types are pliability and comfort.
CE certified armour
In Europe there are two standards covering "motorcyclists' protective clothing against mechanical impact" - EN 1621-1:1997 and EN 1621-2:2003. Both standards assess the performance of protective devices by measuring the force transmitted through it when impacted by a falling mass.
EN 1621-1:1997 assesses devices that are designed to protect the shoulder, elbow and forearm, hip, knee and lower leg regions. The test apparatus consists of a mass of 5 kg with a 40 mm x 30 mm striking face, dropped onto the sample mounted on top of a 50 mm radius hemispherical dome. The anvil is further mounted onto a load cell, allowing a measurement to be made of the force transmitted through the protector. The kinetic energy of the falling mass at impact is required to be 50J.
A protector subjected to this test method is deemed to conform to this standard if the average transmitted force of nine tests is less than 35 kN, with no single test result exceeding 50 kN.
European Standard EN 1621-2:2003 defines two levels of performance for CE approved back protectors. The test apparatus and procedure is similar to that of EN 1621-1:1997, but with a different impactor and anvil configuration. The impactor is a rounded triangular faced prism, of length 160 mm, base 50 mm, height 30.8 mm and radius 12.5 mm. The anvil is a radiused cylinder, with its axis orientated to the direction of impact, of height 190 mm, diameter 100 mm and rounded end radius 150 mm. When tested to the procedure defined in the standard, the two levels of performance are:
- Level 1 protectors: The average peak force recorded below the anvil in the tests shall be below 18 kN, and no single value shall exceed 24 kN.
- Level 2 protectors: The average peak force recorded below the anvil in the tests shall be below 9 kN, and no single value shall exceed 12 kN.
Back protectors are often not included in the standard complement of armor although many jackets allow a back protector to be installed.
Because of the more delicate nature of the spinal column, back protectors require that lower levels of force be transmitted. The introduction to EN 1621-2 states that approximately 13% of motorcyclists injured in road accidents have an injury to this back region. However, only 0.8% of the injured riders suffer a fracture of the spine and less than 0.2% of injured riders have a serious back injury resulting in neurological damage. This is supported by evidence from the MAIDS Report (2004), the most comprehensive in-depth data currently available for Powered Two-Wheelers (PTWs) accidents in Europe.
Serious spinal injures are usually caused by axial forces due to blows on the head, or bending and twisting forces on the back caused by blows to the shoulders, hips and other parts of the body. In the Cambridge Standard for Motorcyclists Clothing, Roderick Woods asserts that the majority of spinal injuries are caused by blows to the hip and shoulders. In the rare circumstance that a motorcyclist received a direct blow to the back the damage would be unmitigable by armor. The concept of a "back protector" is therefore not endorsed by Woods. Although back protectors, as defined in the standard, cannot protect against axial forces they are required to protect the scapula and there is now considerable anecdotal evidence that wearing a certified back protector can significantly reduce trauma in a major accident as they reduce the effect of impacts on the ribs and lessen the blows to internal organs too.