Oscar Egg grew up in Zurich and lived in Paris from 1906 . Egg's father was an engineer. He took his son with him on a trip to France when he was seventeen . He was so enthusiastic about the country that he immediately decided to stay there. From 1911 to 1926 he was a professional cyclist.
Egg's specialty was setting world records on the cycling track : over 500 m (1917), 10 km (1913, 1914), 30 km (1914), 40 km (1914), 50 km (1911, 1915) and 100 km (1917 ). In 1912, 1913 and 1914 he set a world hour record three times, which was only broken by Jan van Hout in 1933 . In some record attempts Egg rode a bike with a streamlined rear fairing, officially "Velofusée", jokingly called "Oscar's Egg" by the competitors.
Egg also distinguished himself as a road driver. He won the 1914 tour of Paris – Tours and 1917 Milan – Turin . In 1914 he won two stages of the Tour de France and in 1919 one of the Giro d'Italia . Also in 1914 he won the Swiss road race championship. Between 1915 and 1924 he also won eight six-day races and the renowned 24-hour Bol d'Or event on the Velodrome in Bordeaux .
Egg, one of the most prominent racing drivers of his time, owned a sports shop in Paris. It was there that the “Egg gear ratio changes” were produced, a new type of gear system specially designed for racing bikes called “Super Champion”. He presented it for the first time in 1932 at the "Paris Salon du Cycle". When gear shifts were first allowed in the Tour de France in 1937 , most drivers chose the “Super Champion”. The consequence of this was that the average speed increased abruptly: In 1937 the last placed driver drove as fast as the winner from the previous year. Egg was also (with Thiberghien) the inventor of light metal drinking bottles in cycling and brought them to the market.