Ran it by the shop and got the headset adjusted properly. Tightened up the brake, brake levers, adjusted barrel adjuster. Greased bars, seatpost, and stem. I use the smooth presta valves, so there is nothing threaded to tighten up.

I can, however, predict when it is going to clunk. It only happens if I hit a bump a little further forward on the front wheel. Here is what I mean if that isn't clear: while looking at the bike from the side, draw an imaginary line extending from the fork to the edge of the wheel. This is just a few inches further forward than where the tire usually contacts the pavement.

Again, I don't make too much contact there, and I can avoid the noise for the most part; every now and then I still ride through a pothole or manhole cover and hear that noise and get a little worried about where it is coming from.

Does this give anyone any ideas about what might be making the noise? It is almost a hollow metallic sound...