Surely we must all be mentally unbalanced to actually enjoy the pain and suffering that are synonymous with bicycle racing.

Who was it that said that "all professional cyclists are cycling away from something [in their pasts]?"

I think there's probably some truth to that, and I wouldn't be surprised if the incidence of mental "illness" (whatever that actually is - depression perhaps?) among professional cyclists is higher than amongst the general population.

Could this actually lead to a high level of substance abuse, whether that be alcohol, cocaine, EPO, whatever? Who knows, but I wouldn't be surprised. And that's without even considering that pressure that these guys are under to win, considering that their livelihoods depend upon it.