I've done the obligatory search and found some info, but nothing that specifically sounds like my issue. I have also posted this in the bicycle mechanics forum here.
Anyway, I just got these new Alex DV 15 wheels for my fixed gear conversion. While taking it for a test ride last night, the brakes squealed something fierce! I also noticed a "feeling" when applying the brakes. It wasn't so much constant vibration, but more of like a "THUNK-THUNK-THUNK" would feel.
The brake pads came w/ the bike so I have no idea how old they are, but they stop me just fine. Also, before I got the new wheels, I used them on the old wheels and there was no squeal or vibration or anything.
Any thoughts? Could it be some sort of film or glazing or something on the new rims?
Most likely it's your fork that's loose. Adjust your headset (tighten) and try riding it again. As for the squealing -- new brake pads or old brake pads? Old brake pads -- check them to see if they're done with, otherwise if they're new and the wheel is new, they're both wearing in somewhat and that might cause the squealing.
Also check for small rocks/glass in your brake pad.
2006 Motobecane Le Champ SL, 2006 Mercier Kilo TT, 2004 Gary Fisher Tassajara
Give it a few weeks. My brakes squealed for a couple weeks while braking hard, when I got new cheap wheels. After about a month, it disappeared. Also make sure your calipers are tight, with no loose bearings.