Portlanders who have lived in this city for less than a decade may not know that the poster child for the infamous "Jail Blazers," the squad of hoopsters who were better known for their off-court exploits than their hardwood skills, was Isiah "J.R." Rider, a player of whose athletic talent was exceeded only by his ability to make poor judgments. Rider came to Portland from Minnesota to play for the Trail Blazers in 1996.  In three years, he alienated an entire city and was eventually traded to the Atlanta Hawks.  The East Bay Express this week published a remarkably tragic story about Rider, who has been living in Oakland for many years.  Called "Fallen Rider," the story traces his origins as one of the most promising athletes to ever emerge from the East Bay to his arrest-filled, drug-laced existence today.  It's a heart-wrenching story, well told.