So, I realize that with only two days remaining in this year's Tour that this is really, really late... But I just found it. And it's a pretty good primer on the Tour de France. It's from last year, so the specifics of last year's race don't apply to this year - but the general stuff about cycling do, and they're written in a way that everyone can understand and appreciate.
Why am I posting this now, even though the Tour is almost over? Because now you'll be prepared for the next bike race I write about. Nothing like planning ahead.