I bought a used bike from a local bike shop today, and the owner didn't know for sure what kind of bike it is, but he said he thought it was a Fisher. I don't know if that's any good, but I took his word for it. It says Shimano on the frame. I feel kinda sketched out, seeing as I don't know anything and this guy could be totally bull****ting me. Are Fisher's any good? Is there any way to tell what kind of bike it is? Also, the rear brakes make a really loud screaming noise when I apply them. Do I need to get new ones?