Hey guys I am new to the cycling thing, I am trying to get a good training plan set up. I race Motocross and I am trying to find a good plan that will help with endurance and strength. I used to run 2-3 miles four days a week but my knee's are shot at the age of 23. So let me know what a good distance ride would be because I have no idea.
Since your knees are shot from running, you may want to consider including circuit training with weights for the upper body. That way some of the joint strain will be more evenly distributed than if you did cycling exclusively. You don't want to risk any more damage to your knees as I'm sure you'll want to use them for the rest of your life.
Use a heart rate monitor to guage your success toward conditioning as lifting weights typically is anaerobic.