On top of the sense of strength and stamina, Miller, who had a race-weight of 68kg, says many of the riders were drawn to the drug because it helped with weight loss. They kept coming back to it, of course, because it was hugely addictive.
"The main attraction for me, personally, was smoking it in a pipe," he says. "I know it was for a lot of other people too. It's like hypnosis. The whirl of the smoke going around in the pipe sucks you in."