I have thought for years that he doped. What did it for me was several years back when just prior to the tour a bunch of big names got found out--elite, world-class athletes who Lance had beaten in competition and yet were all doping. I have a difficult time believing that he's so damn good that without doping he can beat the next best athletes in the world who are. There are people who've reported it, too.
That said, he's never been unequivocally shown as having cheated, and so at this point limiting him from further sport including triathlon seems very harsh. He's 40 and very quickly running out of time for endurance sports. Most are well retired by now.