The effect is really straightforward, what you do is:
1.) Open your photo in photoshop / gimp / whatever image editor you have that supports layers
2.) Copy the image into two layers
3.) "Desaturate" the colors in the TOP layer (I usually muck around with the contrast / brightness as well for dramatic effect) - this may also be labeled as "black & white"
4.) Use the eraser tool with the right types of brushes (generally a large one for the middle, and finer "feathered" ones for the edges so they blend)
5.) Presto! Save as a JPG / PNG. Depending on your photo editor you may have to "merge" the layers or "save as / export" the file so they layers come through.
Note the two layers of your bike, if you look closely you can see the black and white one on top is "empty" in the middle, which allows the color layer of the bike to show through
Note: If you have an iPad / iPhone there is an app called "ColorSplash" that does this too!
Cheers,
Adam
