It's prevalent in all sports Eamonn. The pressures of winning titles and being at the fore front of your chosen sport be it Cycling, track, field sports etc is what drives some competitors to do it, to stay on top. It has also happened recently at the Olympics. Look at what Cian O'Connor went through 8 years ago and that was the animal that had been taking banned substances.
A lot of sports stars are also testing positive for recreational drug taking. One of the most important things you need taking part in sport is a strong will power as well as the physical and skillful attributes. Lance Armstrong was the leading light in his field, but now he will always be remembered for this. Deciding not to proceed with clearing his name will always leave a huge question mark over his name, and I am sure it will cause some debate as to whether he was or wasn't he. Either way it's been a sad falling from grace of someone that was revered around the world.
Rich,