I don't know who organized "Bring Your Own Big Wheel," but looking at the 450+ pictures on Flickr of these grownups racing down Lombard Street, many of whom wore bunny costumes, I have to say it sounds like a lot of fun. In theory. Looks like the rain made the bricks fairly slick.
Liam wants to know why there are no kids in these pictures.
And why people are racing down Lombard Street in big wheels.