How to fix a flat bicycle tire

Updated on .

This assumes the tire is using an inner tube. Wear gloves, as the braking surfaces and tire are pretty dirty and it’s easy to slice open soft hands on a disc rotor or grooved rims.

  1. Remove the wheel: Disengage any rim brakes, loosen the axle, and remove the wheel from the bike. For the rear wheel of a derailer drivetrain, shift to the highest (smallest cog) gear and move the chain out of the way by pulling back on the derailer. Disengage any hub dynamos, shifting mechanisms, or coaster brakes. The tire might need to be fully-deflated (this is where a Presta valve comes in handy) to clear any rim brakes. There are ways to replace a tube without completely removing the wheel (desirable when a hub gear or coaster brake are involved), but they require a rare stay-spreading tool.

  2. Remove the tire: Use a tire lever (Pedro’s are very good, but avoid metal ones that can damage the rim) to get between the bead of the tire and the rim and run it along the circumference of the tire to unseat one side of the tire.

  3. Remove the tube: Unscrew the cap and any collar on the valve stem and pull the inner tube out of the tire.

  4. Find the puncture: Re-inflate the inner tube so the puncture will make noise and exhaust air that you can feel against your face as you rotate the tube.

  5. Inspect the puncture: With the puncture found, inspect it and determine how it happened:

    • A small pinhole is made by a pointy object that got through the tire. Run a rag or (carefully) your fingers along the inside of the tire to check if it’s still lodged in the tire, and remove it. Use the smallest patch in the patch set.

    • Two parallel slices in the tube are created when the tire bottoms out against the rim and crushes the tube. The tire pressure was too low for the terrain. Use the largest patch you have on hand for these.

    • A puncture that’s on the valve side of the tube likely came from the rim, where the rim tape failed and let a spoke nipple rub against the tube. Make sure the rim tape fully covers all the spoke holes of the rim.

    • A pattern of cuts radiating out from a single point in the tube indicates a blowout, which you probably heard before the tire went flat. These are typically too large to be repaired with patches. Replace the tube.

  6. Prepare the area: Rub sandpaper over the area near the puncture to provide a better surface for the glue to adhere to. Keep the area clean of dirt and debris.

  7. Apply glue: Apply a consistent, thin layer of vulcanizing glue to the area and let it dry for about five minutes.

  8. Apply the patch: Remove the foil cover on the patch and place it on top of the puncture. Use a round object, like a frame or pump, and press the patch against the tube with the tire lever, to make sure it’s fully-adhered.

  9. Re-inflate the tube: Pump up the inner tube slightly to make sure it’s now holding air.

  10. Re-insert the tube: Seat the tube into the tire, starting at the valve, and make sure that it doesn’t get caught between the rim and the tire.

  11. Re-seat the tire: Using your hands (not a tire lever), push the tire bead back into the rim. If it gets difficult and tight, pull the other bead closer to the center of the rim, where there’s a deeper (smaller diameter) channel. Most practical wheels don’t need a lever to get the tire back on, but narrow 700C road tires might. Be careful when using a lever to not catch the tube between the tire and the rim, which leads to further tire punctures or blowouts. Add back the collar on the valve stem, to prevent the valve from moving around at low pressures.

  12. Replace the wheel: Put the wheel back in the axle and re-engage any rim brakes. Tighten the thru-axle, quick release lever, or hub nuts.

  13. Re-inflate: Inflate the tube and tire to your desired pressure.