Racism or what??

I have just purchased a few groceries from safeway and I am heading back home on my bike, riding close to the sidewalk, when a car slows down by my side, a guy juts out of the window and lunges against my body. A quick second and the car is gone, leaving me fuming and helpless as I struggle to gain balance. Do I call this an act of racism? Do I call it a prank by college kids? Or is it a combination of both?
This is not the first time an incident of this kind has happened to me. This car slowing down business, cracking some cheap jokes and speeding away has had me frustrated a couple of times in the past. But this time it was physical. Is it something these guys have against someone riding a bike? Or is it something they have against non-whites riding a bike, i.e. a racially motivated prank? I am not sure.
But what I am sure is that if this happens again, I am definitely going to take some action.