Just when the breaks were finally coming his way, Dennis Christopher, 24, found himself in one supporting cast not of his choosing. Waterskiing was "a mistaken experiment," sighs Christopher of the resulting fractured fibula and tibia. "I'm not getting involved in sports anymore, except on film. I'm not agile unless a camera's going."

But Christopher's off-screen klutziness becomes triumphant on-screen prowess. After learning to surf for California Dreaming (he couldn't even swim), he understudied professional bicycle racers for Breaking Away. The proof of the pedaling (he did 95 percent of the race footage) was the undisputed sleeper hit of the summer: The low-budget Rocky on wheels recouped its $2.4 million cost in the first four weeks. Christopher's high comedy and deft, exuberant performance won raves. "It's not easy to bring off that innocence without making it look like Pollyanna," approves director Peter (The Deep) Yates. "He's marvelous."

"He had a lot more faith in me than I had in myself," says Christopher of auditioning for the picture. But the role is uncannily similar to Christopher's life: He plays a young man striving to win the respect of his Indiana community and a father bewildered by his son's pretense of being Italian—even to the point of naming his cat Fellini.

"The secret is that I am Italian," says Dennis, whose last name used to be Carelli. He too had a Federico Fellini fixation. It propelled him to Rome—and accidentally into a scene the director was shooting, thus ruining it. "The butchered pigs had to be put back, the dry ice replaced, the whores put back in the windows," groans Christopher. (But Fellini was somehow charmed enough to cast him as an extra in Roma.) And Breaking A way has earned its star "some respect from my own father," a retired insurance salesman who was troubled by Dennis' interest in acting. "The movie's success was a great thing to be able to share with my old man," exults Christopher. "I sent to Florida for my father and his wife, and they stayed at the Plaza, and we waited at Sardi's for the reviews—the whole trip."

"Dennis is an inspiration," says mentor Tony Perkins, who's watched Christopher bubble up through the ranks. "He's succeeded in this business because there was just no way that he could accept failure." Dennis' Philadelphia childhood put him "well on the road to becoming a creep—being tough, hanging out." But at 13, his mother's death and a particularly inspiring parochial school teacher caused him to reevaluate himself. He took up acting and, after a semester at Temple University, sold his Beatles records to help pay for a ticket to L.A., "where everyone was blow-dried, with tons of experience and hundreds of commercials."

He himself picked up only negligible properties, like Blood and Lace, before a girlfriend convinced him to go to Rome. A year later, back in New York, he says, "I felt like the youngest has-been in the business." He "couldn't sew a button," but Halston gave him a design job with time off for auditions and study with Herbert Berghoff. After a slew of small parts, Yates caught him in Robert Altman's A Wedding.

For the last three months Christopher has been camping in a friend's New York loft, leaving his two cats in his East Hollywood apartment. He hopes to have children someday (he's legal guardian to his widowed sister's two), but for now the cats are his only live-ins. "I'm a bit retarded in that area," he says. "Work has been my lover—I've shied away from any commitments. There's not a lot of me to share right now." He hangs out with actor pals like Shelley Duvall and Penny Milford, repairs his two Nash Metropolitans ("the kind of car that Lois Lane drove in the Superman TV series"), takes photos, buys art and cooks vegetarian meals.

After years of "fishcake" salaries, he doesn't plan to jump at the first six-figure deal that comes along. "I've never chosen or rejected a role because of money," claims Christopher, who has finished a film called Danny Travis and plans to do Good Times/Bad Times as soon as he can return his rented wheelchair. "I'm not too proud to go on unemployment. And this," he says of his triumph in Breaking Away, "is a dream come true."