I'm heading to South Africa for three weeks this December. I can't take my bike, but I really don't want to lose the fitness level I've been working so hard towards for the past 6 months. I ride around 4 times a week, 2 hrs on average per ride. When I go on vacation, I'm thinking that running in the mornings will be a good replacement for lack of riding time. Does anyone know how good of a replacement this is? Is it possible to maintain my fitness level by running for a couple of hours in the morning, three or four mornings per week? What else can I do, assuming no gym access either.