Here is something I heard years ago, I believe it was right after Armstrong's first Tour win. Armstrong has only one testicle, and can survive just fine with one producing testosterone depending on the physiological circumstances.
Under "medical supervision" a recovering cancer patient like him would be allowed to take up to a ratio of 7:1 in synthetic testosterone to make up for any "deficiencies" in testosterone production.
From what I understand Armstrong took advantage of this particular loophole. The UCI was notified of this but the information was never made public because it would cause a stir, even with a TUE. Plus, it would ruin what was turning into the feel-good story of the year back in 1999. Remember it was the race director at the time who declared that year's race "The Tour of Redemption", so there was a lot at stake for all concerned parties involved.
If anyone recalls Chris Boardman suffered from osteoporosis that required hormone therapy which he refused to take while he was riding professionally because he was concerned about the public backlash.
We know the ratio for testing positive for testosterone is 4:1. Armstrong allegedly raced at levels that exceeded this amount. For the apologists, fanboys and weekend armchair physiologists, it is debatable whether testosterone is effective for cycling. Let's just say it is for the sake of argument.
To be allowed to take so much of it explains a lot. It explains Armstrong's relationship between he and the Tour organizers and the UCI. It explains that even amongst dopers, there wasn't a level playing field. This really rips a hole in the argument that "they all doped, so the best rider STILL won".
This is a common fallacy that is spewed by people who refuse to come to grips with the reality that Armstrong is cycling's version of the Six-Million Dollar Man.
Except he was recreated with doping products and protection from testing positive by the governing bodies. The elevated levels of testosterone, along with the EPO/HemAssist that initially made his new "higher cadence" and improved power-to-weight possible. It wasn't because he had dropped 15 or 20 pounds of weight while he was being treated with chemo.