Wasley, Short answer? Photoshop. ;) Longer answer? Use a magic lasso to select the outline of the biker. You now have 'marching ants' around him, letting you know that anything you do will only affect this area. Then, press Shift-ctrl-i to INVERT the selection, meaning everything EXCEPT the biker is now chosen. At that point I desaturated the image, but the selection on my layer limited that to everything outside the biker. Selection of specific portions of an image gives you a lot of power.
i think its a great shot, but can i ask you something? ive been trying to find this out in a very long time. how do you do that? make a certain part of the picture in color and the rest in b&w?