On paper, a duathlon sounds like the ultimate compromise for people who want to race multisport without having to deal with open water swimming. You just run, ride a bike, and run again...simple, right? Except anyone who has ever tried a run-bike-run knows that the second run is a special kind of hell where your legs feel like wet concrete. This is an honest, personal look at the good, the bad, and the sheer psychological torture of duathlons, why we keep signing up for them,