Mark Gainey is the co-founder and chairman of Strava, the rapidly growing social network used by more than 40 million people in 195 countries. From gold-medal efforts to weekend jogs around the park, Strava allows users to share their workouts. Gainey is a Harvard graduate and former venture-capital executive whose earlier venture, Kana Communications, was valued at $10bn and provided a solution to customer-service email in the early days of the internet.