The drug used was Benzedrine, a brand name for a mixture of amphetamines that had been used by the military since the early 1900s.In related news, the International Olympic Committee opened an investigation for possible doping violations in Olympic cycling today in the aftermath of doping confessions by Bjarne Riis, Erik Zabel, Rolf Aldag and Christian Henn, as well as admissions from doctors that they supplied EPO to Team Telekom cyclists. "The IOC finds the revelations in recent days disappointing ... and is therefore determined to look into the matter and any possible impact it might have had on the Olympic Games," the IOC said.
It was generally accepted that the pros used it, especially in the Tour and other big stage races. We didn’t look on it as cheating, the entire Tour de France field was on dope, it only becomes cheating if a substance is banned and only a few do it.
My guess is that doping by professional cyclists can be traced back to the beginning of pro racing in the early 1900s; amphetamines became available about the same time. Six Day Track Racing became immensely popular back then, a sport crying out for a “stay-awake” drug.