If you can imagine a city where people ride bikes instead of cars, with no noise, pollution ,traffic jams, accidents and so on. You'll quickly realise that all car drivers are murderers. A quick reminder of Tetraethyllead should make you realise how many things most people are missing.
My guess is traffic will be just as bad in downtown areas with frequent lights and pedestrian crossings.
While bikes would certainly result in less fatal accidents, I think the frequency of accidents would be higher since bikes can ride so close to each other and pedestrians.
Next time you're in a traffic jam, look at all the cars around you, likely most of them have only one person in it.
Now try to visualize how much space each of those people would take up on a bike instead of a car. All of a sudden you're surrounded by empty space.
Sure its possible to have traffic jams with bikes, but that threshold is so much higher.
Please don't post over-the-top flamebait to HN.