I've been following pro bike racing for 60 years and remember a quote from Jacques Anquetil, who said, in response to a question, "You can't ride the Tour de France on mineral water. You'd have to be an imbecile or hypocrite to imagine that a professional cyclist who rides 235 days a year can hold himself together without stimulants."

He also said that he believed that, having trained and raced as hard as he did, he wouldn't live into old age. He died at age 53.

But, as 63rickert very intelligently noted in a recent thread (maybe this one), most current pros race about a third as much as the pros did in past decades.

We all know how the state of the art has changed in tech, training, nutrition, etc. But my guess is that cutting back on race days and increasing the time spent resting and recuperating have made, if anything, more of a difference than any or maybe all of the other changes.

To me, what beggars belief is the suggestion that doping is responsible for the average speed of entire pelotons increasing as much as it has, despite the fact that almost no one has tested positive.