Career
He made his Grand Prix debut in 1984, racing in the 250cc class. He continued racing in the 250cc in 1985, 1986 and 1987. In 1988 he made the switch to racing production based motorcycles in the inaugural Superbike World Championship.
Mertens raced in the Superbike class until 1994 with his best result being a second-place finish behind Fred Merkel in the 1989 season, while riding for Honda.
In 1995 he began to compete in the motorcycle Endurance World Championship, winning that title in 1995 and 2002.
