There are four riders in this shot - two easy to spot, two less easily identifiable. You don't realise just how quick anything goes until you try to shoot it with shutter delay. These images were taken at 1/20s, anything slower and the trails quickly disappeared.
I'm a little disappointed I didn't try to do anything with the DOF, as the pillars and wall do merge somewhat, but with all the colour and the glorious reflective puddle, I thought it was worth posting regardless.
See Near Mist (Southbank Bike Riders), London on Flickr for additional notes and comments.