Social entrepreneurs, Barry Coleman explains, consistently ride in that cushion, where there is plenty of potential to get ahead and just as much to slide out of control. It is a place where guts and determination are required, and where skill and expertise can pay off. Barry should know. He and his wife aren’t just race enthusiasts, they are social entrepreneurs: founders of Riders for Health, an organization that manages transportation systems for the delivery of health care in seven countries across sub-Saharan Africa.