When I apply either the front or back caliper brake on my road bike I get a "knocking' or "tapping" noise not unlike a bike computer sensor hitting the magnet. Unfortunately, that is not the problem. Usually the brakes must be used for a while to have the noise start. Once the noise starts it can occur every time the brakes are applied on a ride of twenty miles or more but not when I transport the bike to my my mechanic by car after the ride. Frustrating! The brake pads are in good condition. The wheels are Campy Euros and the calipers Campy as well. The wheels are not out of true. The bike is eight months old. The noise has been occuring for one month.