I used 2 SB-800 strobes placed on the parking garage level below where I was photographing from. Both strobes where zoom out to the 105 position and set to full power. They where slaved using Pocket Wizards.
I placed my camera flash sync to "rear curtain". By doing so, I am able to capture the start of the blur and than freeze the action with the firing of the strobes.
Hope you like it.