From the hills of Concord to the flats of Oakland, Alameda County's 2010 Bike Commuter of the Year totes electric grinders, saws, braces, scissors and the occasional prosthetic limb to work via her purple Rockhopper mountain bike, rain or shine. After 10 years of driving from her Oakland home to work sites as far-flung as Lafayette, Antioch and Oakley, sometimes all in one day, T.D. Fisher was fed up. “I felt like I lived in my car. I would make panicky calls to friends saying, 'I am desperate for a hike, can I see you after work?' ” said the orthotist, who designs prosthetic devices for children.