Lance can't run a 6.5 minute time on a 2.4 km course. Thats just over a 4 minute mile and riding a bike 6 hrs a day will not make you run a 4 minute mile nor be able to hold that pace for 1.5 mile(2.4km).
Lances heart is 1/3 larger than the average human and since the heart is a muscle, and if you train you heart, it will therefore gain more muscle mass. Doing so will increse your Vo2. This is not easy though. Thats why you should aim to train at like 80%-90%(I think) of your maximum heart rate in order to reap the best benifits. LSD will not increase your Vo2, but will help better your body's energy systems and the such. If you arent breathing hard, your not working on the Vo2 systems so shorter rides, but not too short, with a higher speed will help you increase your Vo2. You don't want to reach the anerobic level either, this is considered over-doing it on longer rides, but its perfect for speedwork and the such. Anyways, Lance trains insanely hard and has IMHO earned that Vo2 of his. BTW....your fist will not get bigger when your heart does