For years one of racing's most nomadic jockeys, Aaron Gryder has settled his tack in New York in recent years and has become a respected member of the year-round jockey's colony there. A 30-year-old native of West Covina, California, Gryder earned his first victory in Tijuana, Mexico, in early 1987 and wasted little time establishing himself on the Southern California circuit, winning a riding title at Hollywood Park and the 1987 Matriarch Invitational Stakes (G1) and `88 Beverly Hills Handicap (G1). But Gryder left Southern California in the late 1980s and spent most of the next decade drifting from one circuit to another, always enjoying success but