The Nike+ sensor consists of just three parts. There’s an accelerometer that detects when your foot hits and leaves the ground, calculating that all-important contact time. There’s a transmitter that sends the information to a receiver, one that’s either clipped onto an iPod nano or built into the second-generation iPod touch. And there’s the battery. That’s what Nike+ is. What’s more interesting is what Nike+ isn’t. There’s no GPS that automatically tracks your routes—if you want to map your run, you have to do it manually on the Nike site. There’s no heart rate monitor, so even though you know how far and how fast you’ve traveled, you don’t know what level of cardiovascular exertion it required. “We really wanted to separate ourselves from that sort of very technical, geeky side of things,” Tchao says. “Everyone understands speed and distance.” In other words, Nike+ isn’t a perfect tool; it wasn’t designed to be. But it’s good enough, and more crucially, it’s simple. Nike learned a huge lesson from Apple: The iPod wasn’t a massive hit because it was the most powerful music player on the market but because it offered the easiest, most streamlined user experience. But that simple, dual-variable tracking can lead to novel insights, especially once you have so many people feeding in data: The most popular day for running is Sunday, and most Nike+ users tend to work out in the evening. After the holidays, there’s a huge increase in the number of goals that runners set; this past January, they set 312 percent more goals than the month before. There’s something even deeper. Nike has discovered that there’s a magic number for a Nike+ user: five. If someone uploads only a couple of runs to the site, they might just be trying it out. But once they hit five runs, they’re massively more likely to keep running and uploading data. At five runs, they’ve gotten hooked on what their data tells them about themselves.
