Education
At the same Olympics he finished 27th in the individual road race.
At the same Olympics he finished 27th in the individual road race.
In the 1974 Tour de France, Karstens finished second in the fourth stage. Afterwards, he forgot to take the doping tests. The tour organisation set him back to the last place of the stage results, and gave him 10 minutes penalty time in the overall classification, which made him lose his third place.
One day later, the jury took the penalty time back.
After the Olympic Games, Karstens started a successful professional career, where he won six stages in the Tour de France, 14 stages in the Vuelta a España, 1 stage in the Giro d"Italia, and other races such as Paris–Tours and General Practice Fourmies. He became Dutch national road race champion in 1966. Thanks to 5 seconds of bonification that Karstens won during intermediate sprints, he took over the yellow jersey from Eddy Merckx.