I don't feel it now, but could this create some problems in the future? (i.e. knee problems) I've heard that running tears up your knees and ankles, does biking do the same? Is the thing about running even true?
Running is hard on the knees but it takes years and years to do damage. Cycling is actually good for the knees because it strengthens the muscles and tendons without the jarring of the joints. Cycling doesn't help to build bone density like running does so don't give up on running if you like it. Chances are running wont affect you until you get a lot older and you do a lot of running.
Cycling is a cardiovascular exercise so you can do it as much as you like.
Learn to pedal at a high cadence 70-90 rpm's with a lite pressure on the pedals. That will keep you legs from getting tired and you can go for a very long time. Pedaling slow and mashing on the pedals is harder on the knees and will kill your legs quickly. Pick a gear that you can pedal easily but get your breathing to the point where you can still talk but not sing.
