Lance Armstrong's retirement may cost Outdoor Life Network some viewers, but even a 40 percent drop in viewership should leave it in good shape.

Armstrong has taken a sporting event few Americans ever cared about in the past and put in front and center for U.S. sports fans.

NEW YORK (CNN/Money) - This Sunday, a number of sports fans tuned in to watch the Tour de France for the first time, just to see American Lance Armstrong win the grueling race for an unprecedented seventh straight year.

But it probably won't match the number of viewers who will be tuning into the Tour for the last time.

Armstrong has taken a sporting event that was obscure to most Americans, and made it famous. His exploits regularly merit stories not just in the sports pages of U.S. newspapers, but on the front pages. And he has graced the cover of Sports Illustrated eight times, including his 2002 Sportsman of the Year win.

In March, before this current crush of attention started, 87 percent of sports fans knew who Armstrong was, according to a survey by Marketing Evaluations Inc. That makes him better known than all but a handful of athletes in the more mainstream sports.

But Armstrong's expected retirement after Sunday will likely let all the air and buzz out of his sport for most U.S. sports fans.

Outdoor Life Network, which saw its ratings for the Tour more than triple from 2001 through 2004, is seeing viewership up another 20 to 30 percent this year, according to Gavin Harvey, president of the Comcast-owned niche sports network. The coverage is the best-watched programming on the network.

But Harvey was realistic when I asked him if ratings were going to fall off a cliff after Lance.

"It depends what you mean by cliff," he said. "We've known he wasn't going to ride forever, and we've been preparing for this (retirement) the last couple of tours."

One thing working for OLN is that while most fans follow Armstrong in news and sports reports, the network's broadcasts were watched by only about 1 million households, or 1 percent of the nation's homes, last year.

Even with another healthy increase this year, those numbers suggest it's the nation's more committed cycling fans base that's taking the time to watch large chunks of its 320 hours of coverage of this year's race.

With Armstrong out of the race, only committed U.S. fans will watch next year. But there will be more of them than the sport could only have dreamed of when Armstrong started winning in 1999.

So Harvey thinks OLN will be in good shape even if it takes a viewership hit that would be considered a nuclear meltdown in more mainstream sports.

"If we see a dramatic shrinkage, if we drop 40 percent, back to between 2003 and 2004 levels, to me that's not falling off the map," he said.

Even if there are far fewer people watching the tour next year, it doesn't mean we'll be see a lot less of Armstrong in the years to come.

First of all part of the sponsorship agreement between Discovery Communications and Armstrong's team for this and two more years calls for the racer to appear on various shows on the Discovery Channel as well as other cable networks the company operates, such as the Travel Channel. That helped the team get a reported $10 million from the team's prime sponsor, even though Armstrong would be in the Tour only one of those years.

"He may prove to be more valuable for them in his post race career than during the career," said Dan Osipow, spokesman for the team.

Then there's his strong endorsement career, which also is like to keep rolling after his career. The combination of an inspirational personal story -- he overcame cancer before he started this strong of championships -- combined with his dominance of a physically challenging sport and the fact that he's going out on top will keep him among the top endorsers for years to come, according to industry experts.

"I think he's going to have great staying power, because of what he represents to so many different people," said Jeff Chown of The Marketing Arm, which negotiates deals between athletes and sponsors. "He's a cancer survivor, a champion and to a lot of people he's very patriotic because he's representing America overseas."

If Armstrong had failed in his bid for a seventh straight championship, it would have not been that great a blow to his post-retirement endorsement potential, said Chown. But victory should make him even more marketable.

"A sponsor wants the lasting memory of an athlete to be as a winner to the consumer, and that's what Lance has," Chown said.

Armstrong has annual endorsement income of $17.5 million according to Sports Illustrated. That puts him No. 8 among active athletes competing in the United States. according to data collected by the magazine. Chown believes it'll be a number of years before he even slips below the $10 million level -- unlike Michael Jordan, who has become far less visible in his current retirement.

"It's easier for an individual sport athlete to maintain staying power in the endorsement world," said Chown, pointing out that golfer Arnold Palmer was still doing commercials years after he stopped winning on the PGA tour.

"Lance is a unique athlete," he said. "That uniqueness and his story will keep him relevant for years to come."

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