In the Cancellara video, the riders around and in-front ease up a bit just as he accelerates. It does look odd, but he's a freak of nature when it comes to long, solo efforts. And, he rarely looks "out of sorts" on the bike. The only time I recall seeing him look completely gassed was after winning Paris-Roubaix a few years ago. And that was after he won and collapsed in the in-field.