It actually hooks to the top of the fender, I then cut around it and took all the material from the fenders out that was in front of it. Here is a pic from the top, before I cut the fenders out.
The bigger tires are in the works, that's why I did it, I kept hitting my fenders with those tires. The tubes will definately bend if they are hit but I figure I can just bend them back or make them again.