Ottenbros, born in Alkmaar, became world champion on the road in 1969 in Zolder, Belgium, completely unexpectedly. In the previous years he had won two stages in the Tour of Switzerland and a stage in the Tour of Belgium. After winning the world title, he triumphed only once, in the Tour de Luxembourg.
Ottenbros barely raced in the following years, partly due to injuries, and in 1976 he left his sport disillusioned.