Bill Bowerman, cofounder of Nike, created the first rubber sole for athletic shoes by experimenting with rubber in his wife's waffle iron. Although Bowerman did not invent the first rubber-soled shoe, he did create the first running shoe with the waffle iron design, which he believed would give the shoes traction without having to use metal spikes.
Bowerman was a well-respected track and field coach at the University of Oregon in the 1950s. He was always trying to find ways to improve the athletic shoes of his student athletes. He teamed up with one of his former students, Phil Knight, to form a footwear distribution company, which later become Nike. Knight handled most of the business side of the company, while Bowerman continued to try to improve the athletic shoe. According to the National Running Center, in 1971 Bowerman was looking at his wife's waffle iron and realized that the waffle tread shape, when inverted, would be perfect for providing traction as well as springiness to running shoes. He used his wife's waffle iron to create prototypes, pouring rubber into the iron to cook it, then attaching it to the running shoes he designed. Nike debuted the first waffle-iron, rubber-soled shoes, known as the Waffle Trainer, in 1974. The shoe was a huge hit and helped to propel Nike into becoming one of the world's largest athletic shoes companies.