I remember reading a while back about Lance not being a fan of "compact geometery" but using it anyway on newer bikes. I assumed "compact geometry" meant shorter seat tube and then longer seat post. So the bike he's riding up there may actually be a lower frame than what he rode in the past.

Frame sizes have varied drastically, largely due to custom and expectation. You see some of the old pictures where people rode bikes with huge frames where they just had to dismount to stop; standover height exceeded their inseam, even on tiptoe. And of course, coming from the high-wheeler era, nobody thought that was odd. The flip side is department store mountain bikes or BMX-type bikes, where the smaller it is, the more people can fit on it, theoretically.