I took my less than 2 week old '07 Trek 3700 out for a ride yesterday and broke the little plastic disc that fits between the rear cassette and wheel. It is frustrating because I know I need special tools to remove the cassette to replace it or take it to a dealer to get it replaced. I called a Trek dealer yesterday and he said it is not a warranty part. He also said that a lot of people ride without them. I got a weed hung in it and it snapped off 1 of the little pegs that hold it on. Just out of curiousity, how important is this piece? Should I just have it removed or have another one put on? I am assuming it is there to keep chain lube off the spokes.