The overwhelmingly most common one I see is cyclists not stopping at STOP signs (or worse, red lights), and the real crazy ones appear to not even slow down.
It is illegal to run a stop sign, and it is certainly possible a car (crossways or turning) will arrive first and have right of way. So a car is turning, why should it expect a cyclist to come plowing through on a whim?
Again: it is ILLEGAL for cyclists to run stop signs. You have to stop, just like a car. (And in case you think it’s no big deal, I see plenty of cars that aren’t too good at stopping either. You want to hit them?)