The Streetsblog echo chamber

SF Streetsblog's account of this accident simply assumes that mom and her toddler were the latest victims in the war between wicked motor vehicles and cyclists. The wisdom of taking your child on your bike and riding on Geary Blvd. is not questioned. Nor is it questioned in any of the 38 comments to the story that mostly wonder what the proper punishment for the driver should be.

If the law requires special safety seats for small children in motor vehicles, why is it still legal for parents to take their children with them on bikes? I guess we'll have to wait for some children to be killed before we have that public debate. 

Why is this legal?