user: Question: Which category earlier than 2006 has Bart Brentjens as rider 2?
Columns: ['Date', 'Category', 'Team', 'Rider 1', 'Rider 2']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2004.0, 'Men', 'Focus/Rocky Mountain', 'Mannie Heymans', 'Karl Platt']
SQL:

assistant: SELECT "Category" FROM "Table" WHERE "Date" < 2006.0 AND "Rider 2" = 'Bart Brentjens';