The 19-year-old exercise rider who accompanied Preakness candidate Partez from Churchill Downs to Pimlico had never been to the Maryland race track before, and yet the place seemed hauntingly familiar.

He remembers the night of May 3, 1978, when he watched over and over on the television in Mexico City the films of the second race at Pimlico. As the field turned into the stretch, a filly broke her leg and fell, and two other horses fell over her. The boy watched as his brother, jockey Robert Pineda, tumbled to the ground in the midst of the pileup and was kicked by several of the trailing horses. He died almost immediately of head and neck injuries.

David Pineda remembers, too, the day of Jan. 18, 1975, when his family received the phone call that told them the oldest of his seven brothers and sisters had died on the race track. Alvaro Pineda, a gifted and accomplished rider, was trying to dismount from a jumpy colt in the starting gate at Santa Anita when the animal reared unexpectedly and crushed his skull.

After Alvaro's death, his mother asked David, the youngest of the family. "Do you still want to ride?"

"Yes, I like it," the boy said.

After Robert's death, she repeated the question.

David, then 16, gave her the same answer.

"I'd always wanted to go to the track," Pineda said, "but Mom had wanted me to go to school. Three years ago I went to the same trainer who had taught my brothers, and I started learning." He went through the usual initiation of an aspiring rider, mucking out stalls while he was learning the basics, and rode in a dozen or so races. But he decided, like his brothers, that his future lay in the United States, and so he set out for California.

There he went to work for Wayne Lukas, the man who trained Codex to win the Preakness last year. Lukas sees the potential in the young man, and trusts Pineda enough in the mornings to put him on Partez, who finished third in Saturday's Kentucky Derby. When Lukas thinks Pineda has enough seasoning, he will let him ride in the afternoons.

"He's very serious," Lukas said. "He 's still pretty quiet and reserved, but one of these days I'll put him on a 3-to-2 shot to get him rolling, and he'll get cocky soon enough. His brothers' deaths haven't affected him mentally, as far as I can see. I've put him on some 2-year-olds who were a little wild but I never got the feeling he was thinking, 'I want to get out of here!"

Pineda knows that anyone who wants to succeed as a jockey must banish fear from his mind, or even the realization that what he is doing involves physical risks. He knows, therefore, that he cannot allow himself to even think too much of his brothers' deaths. "If I pay too much attention," he said, "it's going to hurt more."

But he has not forgotten them.When Partez was about to go from California to Kentucky, Lukas instructed his exercise boy and groom to travel light, to take only the basics. For Pineda, the basics included a large, wood-framed picture of Alvaro, which he hung on the wall of his room at Churchill Downs. The memory of his brothers evokes for him the promise offered by a career as a jockey, rather than the hazards.