Starting in Bloomington, Indiana, Melissa Henige and Andy Davis have embarked on an ambitious cross-county bike trip that has brought them to Madison en route to the west coast. They visited Isthmus today to talk about Changing Gears, their survey of sustainability initiatives along their route. They intend to collect these initiatives at changinggearsmovie.com/ and in a documentary film about their expedition, and take what they find along the way back to Bloomington, where they live. During their Isthmus visit earlier today, Henige and Davis talked about how they define sustainability, how long they'll be in Madison and how they plan to spend their time during those days.