Before the ‘bike boom’ of the 1970s, if you saw a cycle helmet at all it was probably zipping past in a flash of Lycra, attached to the head of a professional cyclist. The first commercially successful helmet, the ‘Bell Biker’, was released in 1975 but it had poor ventilation and could be very sweaty. Around 1990, a new construction technique was invented, called in-mould microshell, still the model of choice of many BMX bikers and skaters.
