span style='font-size:18px'>Step 2 -/span> Finding the correct alignment for both headset cups is the most important step of the installation process. Both the upper and lower headset cups employ eccentric bearing bores in order to achieve the angle adjustment, but this means that they also must be perfectly aligned with each other when pressed into the head tube. The easiest way to accomplish this is to find the exact center point of the head tube, and then line that up with the alignment markings on both cups.br>br>Use a caliper to find the center line of your bike's top tube by closing down the jaws on each side of the tube, using a felt to mark the center point. Do this at two or three points along its length, including just aft of the head tube.