That seems besides the point in this case though since the author himself describes these as 'shenanigans that had rarely earned my own classmates anything more than raised eyebrows and scoldings.'
The author probably was not in a dirt-bike biker gang when he was a kid, as far as I know that phenomenon is new.
(And honestly, I am surprised that the police were able to catch any of them in the first place. Chasing them down city streets would be extremely dangerous...)
Even if those kids had nothing to do with those gangs, riding dirt-bikes in a city is clearly anti-social behavior that needs to end. If there is a racial bias in the enforcement of those laws, that needs to end too, and the white kids need the book thrown at them too for it, but I really don't believe that the author use to get away with riding dirt bikes around in cities. That isn't standard teenager shenanigans.