This is a little hard to explain, but I've been noticing lately that when I ride at a fairly high speed, in the drops, that my bike feels very unstable for some reason. It feels almost like the spokes are loose or something. If I go arrow straight it's ok but if I turn back and forth any at all it has a very loose feeling to it. I'm wondering if it has something to do with my Spinergy wheels. They are the X-Aero wheels which have the "PBO" carbon spokes. I had my LBS go over my bike a few months ago and now I'm wondering if it's something they did. Anyone else ever had their bike feel like this?? Very unnerving when you're flying down a big hill at 35+mph and the damn thing feels like it's gonna buck you off any second. Like I said, I only notice this feeling in the drops....when I ride on the hoods it feels fine. Very strange.

either find time yourself to check ever screw on the bike or take it to a bike shop and ask them what they think

My bike is very unstable at high speeds. Fortunately I know why. Its a combination of less rider control in the drops and a steep head tube angle with minimal fork rake. Change wheels and see what happens....If it persists follow addicteds advice..