For the past week or so I have been noticing a faint ringing sound when I am in first gear in low rpm's(3,000-6,000) then it either stops making the noise or the bike just gets too loud for it to be audible I'm not sure. It sounds almost like a piece of metal scraping on the ground but it is not loud at all. It's sort of like the sound the brake pad of a car makes when they wear down to the little metal sensor, but I don't think its my brakes because they seem to be functioning fine. Has anyone else experienced this? I have no idea what it could be and cannot seem to pinpoint where the noise is coming from. Should I be worried? I thought I would try to find the problem myself before I let a mechanic take all my money for a small issue.