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 motorcycle armor
This armour is either closed cell or open-cell foam and in various densities all the way up to a fairly hard foam used in helmets. Hard foams absorb impact/shock by destructive decomposition so they can only be used to protect for one incident and must be replaced. Soft foams offer little protection with close-cell foams providing a bit more protection than open-cell foams..
Of foam type armors, memory-foam armor achieves a higher level of impact absorption compared to open/closed-cell types above. Memory-foam rebounds slowly after compression.. It is a very dense foam.
These are gel type impact/shock abosorbers. They are produced in various densities and generally used close to the body for comfort.
Hard armour usually consists of a hard plastic and is designed to resist abrasive and puncture injuries. Hard armour generally is used in conjunction with some impact absorbing foam or other material on the inner surfaces facing the body. This is because hard armour by itself does not provide impact/shock abosorption qualities.
The use of viscoelastic materials in motorcycle armor has allowed for hand (glove) elbow, knee, shoulder, tail-bone, and back armor to be manufactured in a soft and pliable state at rest. Upon the introduction of shock the armor adopts extremely rigid and protective properties. Examples of this armor are SAS-TEC, SW, d3o, Rukka APS air, EXO-TEC and TF armor. They are currently being used in jackets, trousers and suits by manufacturers such as REV'IT!, Firstgear, BMW Apparel, Scorpion, Rukka, Klim and Aerostich respectively.
Viscoelastic armor is soft and body-forming until it is impacted. At impact it reacts quickly to form a rigid mass. d30 armor hardens edge-to-edge. Sas-Tec armor is considered to be a progressive reactive armor in that it hardens to a degree sufficient to counter the force. The material prevents trauma to the human body by three methods:
- Shock Absorption: Material absorbs impact energy through phase change (hardening).
- Shock Delay: Material delays the transmittance of some shock to the human body over a longer period of time.
- Dissipation: Impacts are dissipated over larger areas of the body.
Viscoelastic armor is able to achieve a higher level of shock/impact reducing benefits with more comfort and less bulk than traditional hard armor - foam laminate solutions. Hybrid armor is layered with hard shell outer materials. European standard EN-1621 is used to rate the effectiveness of armor. In this standard, a 5 kg flat impactor impacts the armor at a speed of 4.47 m/s (energy 5x4,47x4,47/2=50 J "Joules"). 50 J of energy is roughly equivalent to dropping a 1Kg mass from a height of 5m (E=mGH). Sensors measure how much force is transmitted through the armor, its peak force in kilo-newtons (kN), and its period (how long it took the force to be transmitted). If the force transmitted through the armor is less than 35 kN then the armor (all armor except back) can attain an EN-1621-1 rating. Standard also includes other factors such as temperature stability and coverage area. The back protection standard is EN-1621-2. That standard rating is based on that energy being less than 18 kN (EN-1621-2 Level 1) or less than 9 kN (EN-1621-2 Level 2).
EN1621-1 Armor for All Body Parts (Except Back/Spine)
There are two European standards covering "motorcyclists' protective clothing against mechanical impact" - EN1621-1 and EN1621-2. EN1621-1 covers any body part protection except back/spine. EN1621-2 covers back/spine. There are updates to the standards from time to time and so the year the update comes out is added as a suffix to the standard such as EN1621-1:1997 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.
EN1621-1 assesses armor designed to protect the shoulder, elbow and forearm, hip, tail-bone, 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 must not exceed 50 J.
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.
EN1621-2 assesses armor designed to protect the back/spine. It is a more stringent standard allowing no more than 18 kN of force to be transmitted to attain Level 1 protection (EN-1621-2 CE Level 1). Armor that allows less than 9 kN of force to be transmitted can attain a Level 2 protection (EN-1621-2 CE Level 2). See section below for more information.
EN1621-2 Back/Spine Protective Armor
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.