I usually wonder why the front end of my Allez wobbles at high speed. My mountain bike with drop bars and street tires hurtles down long smooth descents like a Cadillac but the Allez is "shakey". Don't know why. The wheels spin true. Anything else I should check?
I don't do long fast descents on that bike often, so it hasn't been a frequent problem, but since the topic came up...