Career
He was then injured in an accident at the factory where he worked and had to retire from racing. He became a pacer in motor-paced racing, bringing Piet de Wit, Leo Proost, Martin Venix and Mattheus Pronk to the UCI Motor-paced World Championships titles. His fame as a pacemaker spread beyond the Netherlands, and he was invited to work with German and Belgian cyclists such as Dieter Kemper, Theo Verschueren and Stan Tourné.
Although UCI required the pacer and the cyclist to be from the same country, Koch, together with another international pacer Bruno Walrave, successfully argued in the Dutch court to remove this rule.
The basis for the claim was that Koch and Walrave would lose their jobs as pacers because of the discrimination by their nationality. He retired in 1988/1989 after being injured in a crash during a race.