Originally Posted by SemperFi87

Look at crossfit.com. It is a style of circuit training that mixes cardio, weight lifting, and body weight exercises. While you don't have access to weights, there are a ton of workouts that are run based that mix in body weight exercises for the legs and core. I do these 4-5 times a week (most only take 15-20 minutes) and it has been the single best thing I ave ever done for my OVERALL fitness. Now you can probablly alter the workouts to make them harder on the legs and more cardio, or maybe make them longer, to help out with cycling specific fitness.