I don't know that this year's Tour was "clean"...

... but I definitely think it was cleaner than it's been in a long time.  I say that because there are typically two really clear signs of doping, and we didn't really see either this year.

The first sign that a guy is doping is that he (or she) is on every single day, never has a bad day, and just looks super-human over the course of a three-week grand tour.  That is a physical impossibility for mere mortals, and it generally, normally, always indicates doping.  Lance Armstrong's heyday was a prime example of this kind of thing, and indeed, it was at least partly because Armstrong never, ever had a bad day at the Tour that so many folks were so suspicious.

The other big indicator of doping occurs when a guy (or girl) that no one's ever heard of comes out and just smashes everyone.  An example of that occurred during the Beijing Olympics, when 16-year-old Chinese swimmer Ye Shiwen came out of nowhere to destroy the field in the 400 Meter Individual Medley.  Ye's final 100 meters--the freestyle leg of the race--actually beat Ryan Lochte's, and let me just tell you, as a guy with more than almost two decades of competitive swimming under his belt, that is impossible.  It cannot be done.  There is just no way in Hell.  And the fact that no one had ever heard of Ye before makes it even worse.  Which is why everyone at the time accused her, and let me just tell you, the fact that she didn't test positive means nothing.  Armstrong never tested positive either, because he had a superb chemistry team behind him.

Anyway, this year's Tour de France saw everyone look mortal at one point or another, even the eventual race leader Chris Froome, and frankly, it made the race a lot more exciting.

What we learned, though, over the course of the last three weeks is that a cleaner race means younger riders performing better and finishing higher in the standings.  This, I think, is down solely to the recovery ability of youth, and it may well herald a sea-change in the way teams start preparing for the Tour.

Time will tell.