San Francisco lawsuit in 5... 4... 3...

*Commercial

Rail riders, not cobblestone. This is groovy (literally) but they aren't really riding on the cobblestone.
Using a dirt boards (with inflatable wheels), people have been really riding cobblestone on actual skateboards for years now. Someone should tell them.

Also it's more of a public nuisance than a new sport.

No helmet, shorts and sleeveless.... what could go wrong ?

ehmmm, how do you stop? The board won't ride outside the rail and you can't turn to scrub off speed.

Do you just hope for a kind run out and then bail?

I wondered that too.

I assume (but don't know)---in the San Francisco sequence as he psychotically departs from the intersection of Hyde and Chestnut Street down the Hyde St cable car tracks towards the Ghiradelli Square/Aquatic Park area---that the black thing he is holding in his hand is some sort of control of for a disc brake on the rear wheels? The rotors and pads of which...would be glowing red hot and dripping bits of flaming debris as he comes to a stop before being mashed to by crossing traffic on Bay street at the bottom of the hill? Sort of like in those emergency runway brake tests they do for airliners?