Free Sample
The Complete Handbook of Bicycle Helmets
A practical reference for cyclists, retailers, and safety-conscious professionals who need to understand how helmets work, what actually matters, and how to choose and maintain them correctly.
by Alumigogo Books
Chapter 1: Understanding Bicycle Helmets
A bicycle helmet is a protective device worn on the head during cycling that reduces the risk of head injury during a crash or collision by absorbing and dissipating the kinetic energy generated by impact. Unlike most other safety equipment, a helmet works not by blocking or deflecting a blow, but by slowing the rate at which your head decelerates when it strikes a surface. This fundamental mechanism—controlled deceleration rather than deflection—shapes every engineering decision in helmet design, from the materials used to the fit system that holds it in place.
To understand how a helmet works in practice, you need to understand what happens to your head during a crash. When a cyclist falls or collides with an obstacle, the head moves forward at whatever speed the bike was traveling—anywhere from 10 to 30+ miles per hour depending on the terrain and situation. When the head hits the ground, a tree, or another object, it must stop. The faster it stops, the greater the force applied to your skull and brain. A helmet's job is to stretch out the stopping process over a longer time and distance, reducing the peak force that your head experiences.
This is why a helmet feels soft and crushable when you press on it with your hand. That soft material is expanded polystyrene foam, typically 1.5 to 2.5 inches thick depending on the helmet type. When your head hits a surface at speed, the foam compresses. As it compresses,