The aerodynamic hump, also known as a racing hump or speed hump, was introduced in motorcycle leather jackets to improve aerodynamics and provide additional protection to the rider. The exact date of its introduction is a bit difficult to pinpoint with absolute certainty, as different manufacturers may have implemented it at different times.
These humps were primarily designed to improve stability at high speeds and to help prevent the rider's helmet from being pushed back by wind pressure.
Over time, the aerodynamic hump became a common feature in motorcycle racing suits and later found its way into motorcycle leather jackets designed for street riding as well. It is now a recognizable and popular design element in motorcycle gear, particularly among sport and sport-touring riders.
It's important to note that the specific design and functionality of the aerodynamic hump may have evolved over the years, with advancements in materials and manufacturing techniques leading to improved aerodynamics, impact protection, and rider comfort.