You may already know that Nike created the shoes for the U.S. Olympians (and also China’s Olympic team). A visit to the part of the Nike Web site about these shoes is a veritable encyclopedia/laboratory of custom shoe-making. They offer close-up views and detailed explanations of the design process for every sport’s footwear. Not just running and basketball, but field hockey, BMX, archery, wrestling, badminton, weightlifting and all 28 sports in the summer games.  They first show off their “flywire” technology, which uses cable to function as “synthetic tendons” that wrap around the foot. The development has reduced the shoe’s weight by 50 percent, they say.  A click over to their “lab” profiles the way every shoe was made for each sport. The Ballestra, for example, is for fencers. It has a traction pattern on a flat sole for balance, and extra foam because fencers put seven times their weight onto their front foot with every lunge.  The Grigorios for kayakers are sleek water shoes with split toes that are as close to being barefoot as possible. Equestrians wear the Ippeas, black boots modernized with zippers , lighter heels and a small titanium spur. You can even watch a video conversation with the designer of each shoe. But the best part is that you can buy some. Even if you don’t play badminton, you can check out the shoe and get a pair for $90, or grab a pair of the wildly patterned BMX shoes for $220 (pictured). You can’t buy the custom footwear for every sport, but there are plenty to pick from.