Jean Aerts was a member of an outstanding group of Belgian cyclists in the 1930s. He was the first rider to be both World Amateur Road Race Champion (1927) and World Professional Road Race Champion (1935).
This photo shows Jean Aerts bending over his bike, fiddling with his Super Champion gears, just before the start of the 1935 World Championship Road Race. It is one of two images of Jean on this site, the other is here.
(Source gallica.bnf.fr/ Bibliothèque nationale de France)