When I ran into some challenges with my blood pressure late last year, I began a program of regular aerobic exercise. I was riding indoors on a stationary bike. As the winter months faded into spring, I decided to return to outdoor cycling. I purchased a Trek 2200 road bike.
My training runs right now are about 20kms over mostly hilly terrain. I am maintaining an average speed of 21km/h. And according to this calculator, I am burning about 600 calories an hour. I will gradually build up speed and distance. The workout is far more intense than the indoor bike.
Although the road bike is new, I have been out frequently enough that I need to clean the bike. This site gives you some idea about what it takes to keep a road bike in clean condition.