I have a inexpensive (Trek 700) bike that I ride around town on occasion for errands, it is my rain bike, etc. It has a single chainring and 7sp cassette where the big cassette is this huge 34t thing. And 'behind that' (between the biggest cassette and the spokes) is this plastic thing that looks like a small plate.

This 'plastic plate' has come loose and bangs around (looks like it was held by plastic tabs which broke, I think). What is the purpose of this? Is it strictly to keep the chain from 'overshifting' into the spokes? Can I just take this thing off?

Thanks.

dave