I'm more of a runner than a cyclist (and not a very good one at that, too ). A lot of my friends are more into cycling - some of them very fit... yet none of them seem to run. Similarly, people I know who run don't seem to cycle (bar the few I know who are into triathlons). Anyone else here run much as well as cycle? Why is it, do you think, that the two don't seem to mix much? Different muscles? Not enough hours in the day?