IT HAPPENS every spring. As early as February, wherever novice runners gather here - at the YMCA, in offices, health clubs, apartment hallways and bars - there is talk of one race, the Cherry Blossom Classic.

To run or not to run.

But even as green shoots thrust through the wintry earth, lurking doubts are pushed aside: "After all, it's free . . . I can always drop out . . . wouldn't it be great to tell the guys at the office I ran 10 miles?"

Roughly a third of the 2,230 runners who signed up for the classic at Hains Point on Sunday had never run that far in a race before and many had never run any distance event. There are joggers who enter the classic year after year, yet never aspire to run a marathon, never yearn to test themselves against other runners or to measure themselves against the clock - except at Cherry Blossom time.

The lure of the event is hard to explain. Strictly speaking, the classic isn't much: a 10-mile tour of roads and paths that many Washingtonians use daily for lunch-hour jogging. For seasoned runners, the race is a mere tuneup for the prestigious Boston Marathon two weeks later.

And it isn't glamor. Other races offer expense money to attract big-name athletes, but the classic's organizers have insisted from the beginning that all competitors pay their own way. There has never been a Frank Shorter or Bill Rodgers in the classic, although that day will no doubt come.

In any case, the classic doesn't belong to the superstars. Unlike Boston, which has imposed stringent qualifying standards on runners (and this year rejected a handicapped runner who had missed the cutoff by less than two minutes) the classic remains a "people's race" open to anyone who thinks he can go the distance.

Because it is relatively short, the classic provides an ideal point-of-entry for novices wanting to try road racing in the security of a large, anonymous crowd - middle-aged men in faded college sweat-shirts; strugging housewives. Some men place bets with one another, or with their secretaries, over whether they will finish.

The classic belongs to families. They come in carloads from the suburbs and beyond so that Dad or Mom can run the 10 miles while the kids run the two-mile "fun run" and pick up commemorative patches.

My 7-year-old daughter ran the two-mile for the first time this year, then promptly spilled cocoa on her patch. Kids graduate from the two-mile to the 10-mile, where they run alongside men old enough to be their grandfathers.

The classic belongs to out-of-towners not yet jaded at the Prospect of running in the shadow of the Washington Monument and the Jefferson Memorial. This year they traveled in campers and vans from 25 states and Canada to run throught the drifting cherry blossoms.

Finally, the classic belongs to the D.C. Road Runners Club, whose members regard it as a sort of church picnic or family reunion, a time to renew old acquaintances. Underscoring the social nature of the event this year were post-race brunches there featuring Gatorade, orange juice and beer.

In short, the classic has something for everyone.I have run it four times myself, and each year my perspective has changed. In 1974 I approached it timidly, knowing no one and hoping only to finish. Despite the humbling experience of being passed in the final stetch by a 60-year-old man and a 12-year-old girl. I was exhilarated by th experience and determined to do better.

The next year, thanks in large part to that initial race, I had one marathon under my belt and was training for Boston. The Cherry Blossom Classic became a test of how much I had improved in a year's time as well as a chance to run with new-found friends.

Finally, as a race official the past couple of years, I have observed the painstaking planning and enormous effort that goes into the event, beginning with preliminary meetings in September and climaxing with the work of over 100 nonrunning volunteers on race day.

The classic represents a legacy to Washington of Gar Williams, who was president of the D.C. Road Runners from 1969 to 1973 before moving to Denver. Williams and Ralph Reynolds, then program director of the Central YMCA, conceived the idea of organizing a race to coincide with the Cherry Blossom Festival.

They settled on the 10-mile distance because "if it was longer, you'd be too pooped out for Boston," Williams said. "We didn't want it too short, though. The idea was to have an attractive alternative to a marathon."

From the first year's 129 finishers, the race has grown geometrically to its present size, although not without difficulty. Last fall organizers weathered a major crisis when the original sponsor, a locally-based insurance company, withdrew its support. A new sponsor, Union First National Bank, came to the rescue.

What of the future? Like other major road races, the classic risks falling victim to its own popularity. The 7.8-mile Bay-toBreakers in San Francisco, which last year attracted 9,000 participants, has become less a race than a chaotic sports happening. The Boston Marathon, on the other hand, has sacrificed its democratic traditions in an effort to keep within manageable size.

This year the classic began experiencing growing pains. The Road Runners felt compelled to cut off entries at 2,230 and ended up turning away over 500 latecomers. Coordinator Jeff Darman was besieged with entreaties from the disappointed, some of whom offered fantastic excuses. One man claimed he would be fired unless he and his boss were allowed to compete. he had mailed the entries late, he explained, after assuring his boss everything had been taken care of.

Can the classic grow bigger and retain its charm? Will the Road Runners install a computer to record runners at the finish line? Will the starting line move to Pennsylvania Avenue? Will President Carter fire the starter's pistol? Tune in next spring when the cherry trees bloom . . .