Perhaps the most disliked group of people on the road are cyclists. This is because they have the right to cycle on roads and often slow down traffic. They will pompously ride at a steady pace of 10 MPH while blocking some of the traffic.
While cyclists are hated for being slow and obnoxious, the next most hated group are motorcyclists. This is because they usually speed and ride in and out of traffic dangerous. They will cut people off before speeding away. While they can do this because of their vehicle, they also live dangerously as in an accident they would likely get maimed or even worse.