I have heard tales of the inaccuracies of speed cameras, including the story of the tree that was clocked going 80. But imagine you were on your bicycle. Now certainly, bicycles making use of the street are bound by the traffic laws (all of them, people) but one generally imagines without the aid of serious downhill momentum, speed is not something your average cyclist has to worry to much about exceeding.
So, now imagine your town has installed speed cameras. People grumbled, as they do. People complained that they were sure they had not been going that fast, as they do. Now imagine the speed camera clocked a cyclist going 57. (Cheverly has stopped the program now. As the article helpfully points out, that speed is over the current land speed record for cycling on a flat surface.)
h/t to DCist for the link