Lance Armstrong’s public reputation is down the drain. He’s a cheater and a liar.

You’ve heard this news: The cyclist who survived testicular cancer and went on to win the Tour de France seven times admitted to doping Monday in a 2 1/2-hour interview with Oprah Winfrey to be aired at a later date.

According to news reports, Armstrong decided to admit he doped in an effort to improve his public image. Perhaps by confessing, he reasoned, he wouldn’t suffer years and years of being hounded by his past, much like how baseball player-turned gambler Pete Rose suffers that indignity.

Too late, Lance.

While it may be so that he won’t have to deal with being asked again and again, “Did you dope?” like how Rose is asked, “Did you bet on baseball?” Armstrong can never live down the fact that he cheated in cycling’s biggest event and then lied about it for years and years to investigators and, more importantly, to the fans who defended his innocence.

The doping question, at the point, was almost a foregone conclusion. His admission to Winfrey seems like being the last man on earth to admit the world is round, when he very well knew otherwise.

The question we are waiting for him to answer — and hopefully Winfrey dealt with it — is why he lied about it for so many years and during so many investigations. He not only lied, he issued statement after statement protesting the methods of the investigators and defending his innocence. He even sued book authors, media outlets and assistants who had pointed fingers.

Why not just come clean long, long ago? Live strong? How about live honest?

This week, those investigators surely must feel vindicated. Armstrong, however, seems willing to do anything in order to stay out front of losing his reputation. Hmm. That sounds a lot like how he races, too.

What a shame. The man only admits his guilt publicly when he thinks it can do him good.