If you were able to see any television coverage, you'd notice (under normal circumstances) Lance's cadence is very similar to the other riders. He'll go ballistic for attacks and some time trials. Jan, on the other hand, is almost always pedaling noticably slower.
I think your experience agrees with what most riders find. Pushing a big gear tires muscles, and requires hours for recovery. Whereas spinning a lower gear drives up the heart rate and respiration, and for most of us, is slower. But recovery comes in minutes.