From the 1800s to the 1940s the “invalid chair” was a Victorian house chair on wheels. There were only two functional innovations. In the late 1800s, the wheels were lightened using bicycle technology. In the 1930s, a lightweight folding chair appeared, but it took World War II to replace the house-chair form. Since the 1980s, wheelchair form and function has diversified. Why was change so slow? Why did change happen as it did?