1. At the first hint of a squeak, loosen the bolt (or bolts) that clamp the stem around the handlebar. Slide the bar out, wipe the clamping surface areas on the stem and bar, and lightly grease both surfaces.

    Reinstall the handlebar. If squeaks continue, grease every bolt somehow connected to the stem. It's a long shot, but one of those could be the culprit.
     
  2. If you have a quill stem (which uses an expander bolt to fasten it to the fork steerer tube), pull it out to refresh the grease. This prevents it from rusting to the steerer tube. Unscrew the bolt in the stem's head until it turns freely; don't unscrew it enough to remove it from the stem, or the expander wedge will come off the other end and drop inside the steerer tube. If the stem won't budge, hit the stem bolt with a rubber or plastic mallet. If this doesn't loosen it, turn the frame upside down and pour a rust-loosening solvent or Liquid Wrench into the bottom of the fork's steerer tube. Let it sit for 20-30 minutes (up to 2 hours if it's really stuck), then try knocking the stem bolt again.

    If that doesn't work, either deal with the stem being in that position for the rest of the bike's life, or cut off the stem, take the headset off and consider the fork a casualty of the corrosion war.
     
  3. If you have a threadless stem, loosen it by first unscrewing the top cap all the way, then loosening the stem clamp bolts enough to pull the stem off the top of the steerer tube. Apply a light coat of grease to the clamping surface of the stem and steerer tube.

FROM NOW ON

  • Clean and grease clamping surfaces once a year.
  • Clean and grease quill stems twice a year, threadless once per year.
  • Check for loose bolts every month.