Lance is riding faster than Eddy and the others for a number of reasons:
1) The peloton is so much deeper now; there are so many more cyclists who are good racers compared to the 60s. Guys who are domestiques now would have been team leaders in the 60s if they were performing this well. So that means that the pace of the races will be faster.
2) In relation to the faster courses, the Tour has made some of the stages easier (and thus faster). Also, there were days where you would race twice! One of the years that 7-11 (later became Motorola and could be considered a grandpa to USPS) raced a stage in the morning, got the Maillot Jaune for one of its riders and then have to race a team time trial in the evening. That does not happen anymore.
3) Lance trains for one event: the Tour. Merckx and others were better all around riders in that he wanted to win the Classics as well. Lance no little to no interest in any of the Classics unless they happen to fit into his prep for the Tour.
4) Lance can do #3 because of the money now available. Riders in the old days had to win more and race more to make enough money.
5) Athletes are better prepared nutritionally and in terms of restoration--even outside of any possible medical interventions.
The argument against Lance being doped is that he has been a successul endurance athlete since he was a teenager. Do you think he was doping when he was 19 and doing so well in triathlons?
I fall into the group that does not believe everyone is doping.