My rear hub is making popping noises and has occasionally sounded like metal grinding or something of that nature. The wheel still spins freely without a lot of noise. Yet when I am pedaling there is constant noise, when I put a lot of pressure on the pedals I get that medal grinding noise. I noticed that I can see some of the splines on the freehub body between the wheel and the cassette. I didn't think this was normal but then again I've never really paid attention to it. Is this normal for some of the splines to be showing? My shifting hasn't really been off that would make me think the cassette has moved but maybe it has moved only slightly somehow. Also, what would it entitle for an LBS to check out the hub? Would they have to tear apart the wheel, check out the hub, then rebuild it? By the way, all of these noises are for sure in the rear hub area of my bike so don't tell me to check my pedals/bb/handlebars