This was a Critical Mass event, which is why the bicyclists are taking up all of the street as a way to reclaim the streets and protest the lack of safety for riders under usual conditions. It’s not legal, but protests are never useful if they’re fully legal now, are they.
Of course they are, but bad urban development doesn’t justify people intentionally creating dangerous situations.
They’re creating danger for themselves to make a point. What are you getting on about? The people in cars were not in danger.