Stationary bike ride compared to running?

How do the 2 compare as far as amount of exercise goes? Is riding a stationary bike at jogging pace for 20 minutes an equal exercise to jogging for 20 min.? Im considering replacing some of my running with the stationary bike exercise because of runnings impact on my body. I will add some "sprints" to my workout on the bike, but at a steady, comfortable pace on the bike, how long should I ride to equal 20 min. of jogging?

Unless you go to a spinning class, a stationary bike will not have the same effect on your body as running. When you're on a stationary bike, you use mainly your quads. When you're running/jogging, you're working all of your leg muscles as well as your hips, abs, and back (and even arms if you're using weight).

The best replacement for running with the least amount of impact is the elliptical wheel.

Its great - if you got a chance, change your cardio exercises, if you will do so, you won't get bored very quickly. The main mistake all people do is that they think theres only one cardio exercise available - running on a treadmill.
When they stick to that plan, they quit very quickly, because they don't realize that they can do boxing, tennis, football, stepping, cycling(like you sad :) and yes, my point is that your plan is good.
wish you luck,
Robertas

riding a stationary bike doesn't compare at all to running. when you run you are adding resistance, by having to move your own body weight. a stair climber or step mill is you best choice. if you add the right amount of resistance you can burn up to 1000 calories in an hour.