Bowerman was obsessed with shaving weight off his athletes' running shoes. He believed that custom-made shoes would weigh less on the feet of his runners and cut down on blisters, as well as reduce the overall drag on their energy for every ounce he could remove from the shoe. By his estimation, removing one ounce (28 g) from a shoe, based on a six-foot gait for a runner, would translate in a reduction of 55 pounds (25 kg) of lift over a one-mile (1.6 km) span.