EN
ZHEN 14021: 2003
Stone Shields for off-road motorcycling suited to protect riders against stones and debris. Requirements and test methods.
The standard for body protectors worn while riding off road to protect against minor impacts such as from small stones thrown up during off road riding includes tests for design, dimensions, impact performance and ergonomics.
Stone shields are required to cover a specified minimum area of the wearer’s body, particularly in important zones (such as across the chest). The breast guard in particular must cover the anterior (front) portion of the rib cage including the sternum. Shoulder, bicep and back guards must also cover specific areas of the body if included in the garment. Where areas are covered, the guards are checked for significant gaps in the protective area using a 15 mm diameter tapered probe (the probe should not be allowed to pass through any ventilation holes in the shield).
Ergonomic test
Shields are subjected to an ergonomic assessment, in which they are checked for any significant hindrance to freedom of movement when worn, as well as checks for any potentially dangerous projections or causes of discomfort. In addition, any restraints used for holding the shields in place, or holding additional components (e.g. shoulder guards), are subjected to tensile strength tests to ensure the shield is unlikely to detach from the garment in use.
Impact test
Stone shields are subjected to an impact test performed in a similar manner to that specified in EN 1621-.1 The test is intended to register only the force transmitted over a small area on the wearer’s body rather than distributed over the area of the shield (e.g. a point-load). Therefore, a shield which does not significantly deform under impact will register no force in this test. A hemispherical impactor of mass 1kg is dropped onto the sample so as to produce impact energy of 10J . The sample is mounted on a solid guard ring, which surrounds a shallow domed anvil which is mounted onto a force transducer. This ensures that the force transducer registers force through the material only after it has deformed to the point where it makes contact with the inner anvil. The transmitted force through the stone shield and padding should not exceed 27kN. This test is intended to simulate typical forces exerted on the shields from small objects impacting at relatively high velocities, i.e. stones thrown up from ground surfaces during riding.