76% of male cyclists and 72% of female cyclists reported being harassed while on their bike in a 12 month period. The most reported forms of harassment were driving too close (66%), shouting abuse (63%), and making obscene gestures/sexual harassment (45%) (Heesch et al (2011)).
A number of studies have linked low rates of utility cycling to harassment of cyclists (Garrard et al., 2006, O’Connor and Brown, 2010, Rissel et al., 2002).
The video clip below shows a driver in NSW proving their point by driving on a bike path while cyclists ride on the road. The driver was charged for his aggressive behavior.

Video source: Bicycling Australia