What a strange reunion is taking place for three cycling legends this weekend in California:  

--Lance Armstrong, the 7-time Tour de France winner who is staging a comeback at 37 in part to prove that he's a clean rider and no doper, despite a controversial 2005 report claiming that he'd used the banned substance EPO during his initial Tour victory in 1999, and a just-as-controversial report the next year "exonerating" him from that positive test.

--Floyd Landis, Armstrong's onetime teammate and support rider who won his own Tour de France following Armstrong's retirement, only to have the crown taken away when it turned out he had someone else's testosterone in his veins.

--And Amgen, the inventor of the process to clone human EPO, a miracle drug for anemics and cancer patients, but the cheater's drug of choice in cycling and other endurance sports.  

Yes, the fourth edition of the "Amgen Tour of California" has plenty of irony for everyone, and no doubt some of the news organizations following Lance's return to pro cycling will make at least some mention of the strange juxtapositions during the next week of racing.

With Armstrong making his first appearance in a race that's sponsored by Amgen, I can't help thinking back to the year 2000, when I made a visit to the Amgen 'campus' near Los Angeles.
At that time, EPO had already nearly ruined professional cycling, in part because there was no reliable way to test a cyclist's urine or blood to show that the substance (which occurs naturally in the body) was the cyclist's own or something he injected. (A test would finally arrive that year, which has helped matters immensely.)

Also that year, Lance was following up his first comeback - his incredible win at the 1999 Tour de France after recovering from cancer - with preparations for his second Tour victory. During the 1999 Tour, he had tested positive for a miniscule amount of a banned substance that he explained away as something that was in a cream he used for a saddle sore. It sounded plausible, but it was only natural that following the sport's horrendous 1998 drug scandal, which nearly ended the Tour that year, Armstrong's miraculous comeback in 1999 would raise questions.

As Lance prepared to go for his second Tour win in 2000, I remember him firing back at his critics with a Nike television commercial showing him riding his bicycle in a driving rain. In a voiceover, Lance told us that "everybody wants to know what I'm on," clearly a reference to the lingering drug questions. "What am I on?" he asked. "I'm on my bike, busting my ass, six hours a day. What are you on?"

You had to hand it to him for that kind of bravado.  

It was my San Francisco colleague, Matt Smith, a former pro cyclist, who encouraged me that year to pursue a story by asking a question that we hadn't seen asked by the cycling press.

What, if anything, was Amgen itself, inventor of the substance that was ruining one of the greatest sports spectacles, doing about the worldwide abuse of its product, which the year earlier had brought them $1.8 billion?

The folks at Amgen, after some prodding, agreed to let me come up and look around, but it was clear they thought the widespread abuse of EPO was someone else's problem. With no reliable test to catch cheaters up to then, there had been only so much they could do about safeguarding the substance from unethical doctors or thieves, they told me.

But what about at least appearing to care that their wonder drug was wrecking lives and bringing the Tour to its knees? Other companies at least threw money at "sports institutes" and other PR initiatives to distract people from the negative consequences of, say, using slave labor in India to make soccer balls, or employing children in southeast Asia to make sneakers. I mean, aren't companies at least supposed to pretend that they care?

I guess it took them a while to figure that part out. Six years later, Amgen sponsored the first Tour of California, which has turned out to be a terrific event.

Particularly that first year, when Landis won it. You might remember the situation at the time: Armstrong had just retired, and there was some question as to which American would step forward as the country's leading cyclist. George Hincapie had surprised everyone by winning a mountain stage in the 2005 Tour -- could 2006 be his year? Levi Leipheimer was determined to come out of Lance's shadow and seemed poised to do it. But it was Landis, with solid wins in both of the early-season American stage races -- the Tours of California and Georgia -- who quickly became the one many of us wanted to see win in Paris.

If Lance's escape from the clutches of cancer was a story for the ages, Landis's escape from a Mennonite upbringing was nearly as improbable and fascinating.

Which is one of several reasons why watching Floyd race this week in California will be difficult.  

It will be hard not to think about July 20, 2006, which, without hesitation, I can say was the single greatest day of cycling I've ever witnessed. Yes, better than Greg Lemond's 1989 comeback in Paris (the greatest Tour, without a doubt), or even the many exploits of Armstrong, including his remarkable 'farewell look' at Jan Ullrich on l'Alpe d'Huez in 2001, a dramatic moment to be sure.

When you try to explain the arcane ways of cycling to the uninitiated, one thing you have to spell out is that although a main contender might be trailing by several minutes in a three-week road race, you won't see him simply speed ahead and win a day's stage by that amount to get himself back into contention. It just doesn't happen. Instead, once you're trailing by that much, you have to wait for someone ahead of you on time to crack, to fall back to your position -- because no one, ever, simply speeds ahead to reclaim several minutes against an entire pack of the world's greatest athletes over mountainous terrain that would rip the knees off a mere mortal.

But that's exactly what Floyd Landis did. The day before, on July 19, when many of us believed that he really was going to win the Tour, he'd cracked. He lost ten minutes in a rotten day of climbing, and fell from second place to eleventh. "Well, that's it," I remember thinking, dreading even to watch the next day's race, the 17th stage to Morzine.

But on a bum hip, Landis performed a miracle. He jumped out ahead of the pack nearly from the start of the 201-kilometer course and then stayed there. All day. With the sport's top racers trying to pull him back, he flew up mountains to get a nine minute lead, eventually finishing with a six minute advantage and a look of anger that was not something many of us will ever forget.

It was breathtaking. Ballsy. Insane. He was now just 30 seconds out of first place, with an excellent chance to win the Tour in an upcoming time trial, when only the day before he seemed out of contention.

You know the rest. He went on to win, but then came the news that his urine sample for that epic day to Morzine showed "exogenous" testosterone - meaning that it was not Landis's own. (Experts, meanwhile, explained that the excess testosterone in his system didn't necessarily explain how Landis managed his stunning ride on the 20th, but it did help explain how he recovered so well after his bad experience the day before.) Landis was stripped of the title, and he's been out of the pro peleton ever since. His return -- and few seem to be celebrating it -- will be this weekend's Tour of California.

I'm curious to see how Armstrong interacts with him. Armstrong has said that he welcomes Landis back, that anyone who has paid the penalty should be allowed a second chance. Those are magnanimous words, but being in the presence of Landis -- as well as Ivan Basso, another former Armstrong protege who served an exile for doping -- can't really serve Armstrong's plan to associate himself with clean living. (As does the news, in this week's Times, that Armstrong's much-ballyhooed plans to follow a strict new doping program administered by one of the world's leading drug-testing experts has fallen apart and won't be happening after all.)

Armstrong is making his comeback because he wants to spread his message about fighting cancer. He's also, naturally, interested to see what he can accomplish at 37 against a field that at the moment lacks many truly outstanding stars. But it's also very clear that Armstrong's comeback is an attempt to quiet the drug rumors that haven't gone away, even after nearly four years since his last Tour win.

I mentioned that a test for detecting EPO finally showed up in 2000. Ever since then, Armstrong has always tested negative for the substance. He never hesitates to say that he's the most drug-tested athlete in sport, and that for all that testing there's no evidence that he's ever cheated (the 1999 miniscule saddle-sore-cream result notwithstanding).

But with the EPO test in place, French drug testers decided it might be interesting to analyze older urine samples which had been taken before the test had been developed. In 1999, for example, when they knew there was no test to catch them, had cyclists gotten away with doping?

Armstrong's urine samples from the 1999 Tour were subjected to the new test in 2004. The next year, news of a positive result was leaked to the most Armstrong-hating publication on the planet, the French sporting newspaper l'Equipe.

In the controversy that followed, there were many questions asked, mostly around two main themes. One of those themes interested me, the other less so. The question I really cared about: "was the test reliable?"

Sampling urine to find cloned EPO and identify it as a different substance from the cyclist's own, naturally-produced, EPO is a very complex affair. Would it be reliable to test a sample that had been frozen for several years? Was the chain of custody secure, so that a mistake in identity could be ruled out? Was there certainty that the samples hadn't been contaminated?

The second line of questioning concerned me less, but it boiled down to this: was Armstrong being treated fairly?

Certainly it wasn't in Armstrong's own best interests for the results of his urine tests to be leaked to a publication that perennially looked for reasons to discredit him.

But if the test had reliably produced a positive, it was important to confirm that or rule it out. Armstrong's feelings about the French media were secondary.

Shortly after the claims of the positive had been leaked, cycling's administrative body, the UCI, announced that it would have an independent investigator, a Dutch lawyer named Emile Vrijman, look into the affair. A year later, Vrijman announced his conclusion: His investigation, he said, exonerated Armstrong.

It made for a powerful headline that June, in 2006. I saw "Armstrong Exonerated" all over the place. But few, except for the Times and a few others, seemed interested in what the Dutch investigator had actually found.

I was disappointed that his investigation looked almost exclusively at the second set of questions: in other words, whether Armstrong was being treated fairly. He wasn't, Vrijman concluded.

But that left the main question unanswered: had the 1999 samples produced a reliably positive result or not? For the UCI, the matter is closed. But to me, it was an unsatisfying end to a claim that was controversial from the start.

Because of all the negative test results Armstrong has amassed over the years, I'd like to believe that he's been clean throughout his career.

But it will be strange, at the least, to see him competing against his old companions, the disgraced Landis and Basso, in a race sponsored by the drugmaker of the scourge of cycling.

UPDATE: A question similar to mine - whether it would hurt Lance's image to reunite with dopers Landis and Basso in the upcoming Tour of California - was asked in a slightly different way this afternoon by a journalist, Paul Kimmage, who had written something Lance obviously didn't like. Saying that Kimmage had called him a "cancer on cycling," Armstrong lashed out at Kimmage and then answered that Landis, while he hasn't admitted doping, honestly believes that he didn't break the rules. Watch the video here: