How Does a Helmet Work?

A BMX helmet works by reducing the peak energy upon a violent impact. This usually requires a layer of stiff foam to cushion the blow by crushing. Most helmets do this by using expanded polystyrene (EPS). Once crushed, EPS does not recover. Another, much less common foam, expanded polypropylene (EPP) does recover. The spongy foam inside a BMX helmet is intended to provide comfort and a good fit, not necessarily to minimize impact.

The BMX helmet must stay on your head even when you hit it more than once (for example a car and then the road), so it needs a strong strap and an equally strong fastener. Keep the strap comfortably loose when you're riding, but bear in mind that you must not let it come off or slip enough to leave large areas of your head without protection. If this happens, adjust the straps again or try another helmet.