Sylvère Maes was the leader of a group of Belgian riders who dominated cycling in the 1930s. He won the Tour de France in 1936 (without a derailleur) and 1939 (after succumbing to the charms of a Super Champion changer). In the 1937 Tour he was locked in a duel with Roger Lapébie and was leading the General Classification, when a whole variety of underhand actions by the Tour organisers (all, naturally, favouring the French Lapébie) led Maes to leave the race in disgust.
I remember him primarily as the person who gave his name to 'Maes bends' - as drop handlebars were known in my youth. Sheldon Brown explains:
"The Maes bend is the most common type of drop handlebar. From the center, it goes straight out then bends forward in a gradual curve. When it has bent forward 90 degrees, it turns downward, and bends in a smooth, constant-radius curve approximately 160 degrees, then straightens out. It is usually set at an angle such that the forward-bending section is tilted somewhat downward toward the front. The bottom flat part of the "drops" will normally be level, or slightly down at the rear. It should be adjusted for straight wrists when the hands are resting on the drops."
This, rather moody, shot shows Sylvère Maes climbing the Tourmalet on stage 16, which he won, of the 1936 Tour, which he also won. It is one of five images of him on this site, the others are here, here, here and here.