Motorcycle helmets are typically rated for their ability to withstand impact forces and provide adequate protection to the wearer's head. The most commonly used standard for motorcycle helmet safety ratings is the ECE 22.05 (Economic Commission for Europe) standard, followed by the DOT (Department of Transportation) standard in the United States.
These standards do not specify a particular speed at which the helmet is rated. Instead, they focus on the helmet's ability to absorb and distribute the energy of an impact. The helmets are tested by subjecting them to various types and intensities of impacts, simulating different accident scenarios.
Both the ECE and DOT standards evaluate the helmet's performance in terms of impact attenuation, penetration resistance, retention system effectiveness, field of vision, and other factors. The standards ensure that the helmets provide a minimum level of protection across a range of potential crash situations and speeds.
It's important to note that while motorcycle helmets are designed to provide protection, their effectiveness can vary depending on factors such as the severity of the impact, the speed at which the accident occurs, and the specific circumstances of the crash. It's always advisable to choose a high-quality helmet from a reputable manufacturer and to replace it if it has been involved in a significant impact or shows signs of damage.