contango 

I've never observed such a crackdown. I've had to take evasive action to avoid the usual antisocial cyclists who plough through red lights at pedestrian crossings even when pedestrians are crossing, seen a number of cyclists travelling at speed on pavements (sidewalks) etc.

The problem with crackdowns on cyclists is that the cyclist who is generally responsible but once in a while takes a shortcut (e.g. using the pavement for a short distance when no pedestrians are using it) is more likely to cooperate with the police, while the antisocial cyclist who doesn't care about rules at all and considers the world to be their personal racetrack will simply ignore the police and cycle away. In the absence of any form of registration of bicycles there is little the police can do, unless they are a position to give chase.