Just wanted to clarify my post above: like any rider Cav isn't above suspicion but as ever I give him the benefit of the doubt. Bit like Sagan I see him as a freak of nature, perfectly designed for he does. Like McEwan says, in the drops he's already effortlessly in the perfect aero position. His body shape could have been designed in a lab: big head, narrow shoulders, smally body. I imagine shorter legs give him an acceleration advantage over taller, bigger riders.
Coupled with that is a real mentality, a real determination to win ruthlessly. It means he's never beaten,never backs down, will always try his absolute best. He uses his teammates and more for motivation. He doesn't ride for himself, he rides for other and this fuels his desire to win. A big contrast there with Wiggins, who you feel only rides for himself.
So while I'm sure PEDs would benefit Cav, I also don't think he needs them to do what he does. His palmares is unquestionable from early on, and there are plenty of reasons why he is exceptional at what he does. While a 3 week tour is tough on everyone, Cav stays sheltered in the peloton, never has to take a turn on the front of go back for bottles, and yes mountains are extremely tough for sprinters, to make sure you're within the limit....
But I never look at Cav and think NOT NORMAL.
My opinion of course. I know he raced/races for some dodgy teams.