In general, headset service should be done at least every two years. In dry climates, service intervals may be longer. In wet climates, service may be necessary as often as every 6 months.
You may service your Chris King headset while in the frame using a light solvent based lubricant (e.g., Bullshot aerosol or WD-40,) to flush the bearings. If you have access to the correct tools for the proper removal and reinstallation of Chris King bearing cups, we have found it easier and more effective to remove the cups and use a solvent tank.
Remove snap ring and seal:
Take a pointed instrument, such as a penknife, insert it at the split in the snap ring, and lift the pointed end out. Once the pointed end is free, the remainder of the ring can be removed easily. Lift out the inner seal. At this point the bearing will be exposed.
Clean and re-grease the bearings and replace the seal and snap ring:
With a small brush (e.g., a tooth brush) clean the bearing while rinsing with solvent. If the bearing has been neglected and is frozen, let it soak for a few minutes. Then, rotate the inner race back and forth to work it free. Rinse in solvent and blow dry with an air hose to remove any excess solvent. Test the bearing for smoothness. If the bearing was frozen for too long it may have become damaged or may be too rough and need replacing. However, if the bearing has lost only some of its silky smoothness, it may not be evident at the handlebar once re-greased and reassembled. If bearing replacement is necessary return cup(s) to us to have a new bearing(s) installed
Re-grease the bearings using Bullshot or any other waterproof grease. Carefully wipe off the inner seal and reinstall. Finally, insert the pointed end of the snap ring into the snap ring groove, working it around the bearing until the other end seats and a small gap is noticed. Inspect the rest of the parts for any wear. At this time, you are ready to reassemble the headset and adjust.