One of the reasons I am biking; I used to run. Sorta liked it. think liked music I listened too at same time, almost as much as the run..... One of favorite runs, when used to live in Florida; ran across the new Tampa Bay bridge when it opened- a long time ago..
Wish I could still run, so I could diversify my aerobics when I had too... Particularily, when I did not have the time for long rides; which I tremendously enjoy.
So why do I not run.. It forever screwed up my right knee.
Anyway- running 20 minutes; when I could be cruising up a mountain vista or the coast- what is to compare. Cycling beats out running as being more enjoyable by 1000 to one- anyway... And it will not destroy my left knee; I am pretty well convinced..