Mystery Noise Resolved.
Just got my Titanium Macalu back from the lbs (Vecchios in Boulder - unpaid advertisement). Besides a normal end of year shakedown I asked them to look into a mysterious (to me) CLUNK (thunk?) which occurred during high speed descents whenever I crossed pavement rivulets which run perpendicular to the direction of the road. A very noticable sound. I thought it might be something in the headset, but the steering was tight. The fork passed all of my inspections. The bike is setup pure Ultegra.
Its always made this sound, a heavy sharp THUNK (clunk?) when crossing these spots in the road.
This year was my first on the Parlee CF bike. All Record. Same roads. Same speeds. No CLUNK.
Jim at Vecchios said they were able to reproduce the noise. And in fact, I did so myself in the shop after they explained to me what it was.
The Ultegra levers were snapping back and forward when i would hit one of these shallow channels in the pavement. I got the same sound just by bouncing the front wheel pretty sharply and hard on the shop floor.
According to the guys at the shop it is inherent in the design/makeup of the Shimano shifters; their weight and how much mechanism is loaded into the shifter body.