I have AC All Mountain 29er wheelset (new to me, I think a 2011), and the rear wheel/hub spin just fine, but when under heavy load (hard climbing), I get a clicking/pinging noise. I sounds more like spokes bedding in, but it is not going away. Not incredibly loud, but not acceptable either.

I tried lube where the spokes touch, as well as dropped a few drops on each spoke/nipple. No luck.

Any thoughts? New step is open hub up and play around (check bearings, lube some surfaces ???), but the thing spins so well I don't want to open and screw with it if I don't have to.