Given that cycling tests its atheletes much more rigorously and for many more substances and possible doping method than any other major sport, to assume cycling is more full of dopers does it a great disservice, but also lets everyone off too easily. It seems terribly naïve to assume that doping isn't rampant in most major league sports. Combine virtually non-existant penalties, lax or no testing, and salaries far beyond what the average professional athlete could get outside of sports and you have a sytem gauranteed to produce results. What the extensive and highly invasive testing regime professional cycling has taught us is that if an athlete can cheat, he will. Athletes will cheat even when it's likely they'll be caught. We already know what professional sports will look like with unchecked doping: we have it now.

It also seems that the death of athletes from pushing the envelope more and more would be at least a slight PR problem, no?

For example, right now in cycling, they guard against rampant EPO use by setting a baseline hemocrit level of 50. To give you an idea of what this means, Bjarne Riis (1996 TdF winner and current manager of Team CSC) won with a hemocrit level above 60. EPO has this particular trait where the markers for EPO use goes away within 10 days, but your hemocrit level stays high and gradually decreases. As such, athletes now will load up on EPO 2 - 3 weeks prior to major tours, and then through experience and a doctor's assistant, ensure that the doping levels are such that on race day, they have a hemocrit close, but not above 50.

Prior to this 50 rule, in the early 90's and mid-90's, athletes would be so doped up with EPO, that their blood become close to oatmeal do to the high level of red blood cells in the blood. Athletes literally would have heart rate monitors attached to their chests while they slept, and if their HR got too low, it would wake them up, and they would do aerobics to get their HR up high enough to ensure that the blood would not pool and clot. A bunch of amateur Belgian riders died from heart attacks and anuerisms due to this problem.

If you were to allow doping, you would end-up with this and worse. An athlete riding at a dangerously high hemocrit level of say, 60, who loses the TdF in one year, may take the risk to push it to 65 in the hopes that this will put him over.

Now - you could take the argument that it is his life, let him do to it as he pleases. One problem...the sport would lose its fan base. People would become disgusted if they felt they were watching ticking time bombs for their amusement.

Finally - the above 50 hemocrit level is exactly why the UCI (Cycling's governing body) has random drug tests throughout the year and why Rasmussan was kicked out of the TdF while wearing the Yellow Jersey. Rasmussan lied about his whereabout, saying he was in Mexico, when in reality he was in Italy. The most plausible reason that he lied is because he was working with a doctor, doped up on EPO. Had he been tested then, he would have been caught.