Patch or replace the inner tube

Remove the wheel, extract the punctured tube, and either patch the hole with a vulcanizing patch kit or install a new tube. This is the fundamental flat-tire repair that every cyclist should know.

Steps

1. Remove the wheel: Release the brake if needed and open the quick-release lever or loosen the axle nuts. Remove the wheel from the frame.
2. Unseat the tire bead: Insert a tire lever under the tire edge opposite the valve and pry the bead over the rim. Slide a second lever around to free one side completely.
3. Pull out the tube: Extract the deflated tube, pulling the valve stem out last.
4. Locate the puncture: Inflate the tube slightly and listen for hissing, or submerge it in water and watch for bubbles.
5. Patch or replace: To patch, roughen the area with sandpaper, apply vulcanizing cement, let it turn tacky, then press a patch firmly in place for one minute. To replace, use a new tube of the correct size.
6. Inspect the tire: Run your fingers along the inside of the tire casing and remove any embedded glass, thorns, or wire.
7. Reinstall the tube: Inflate the new or patched tube just enough to give it shape. Insert the valve stem through the rim hole and tuck the tube inside the tire.
8. Reseat the tire: Push the bead back inside the rim with your thumbs, working from opposite the valve toward it. Use tire levers carefully for the last tight section, avoiding pinching the tube.
9. Inflate and remount: Inflate to the pressure printed on the tire sidewall. Reseat the wheel in the frame and re-engage the brake.

Tips

• Check the valve stem area too; slow leaks often originate at the base of the valve
• Carry at least two tire levers; plastic ones are less likely to damage the rim
• After patching, wait a full minute before reinstalling to let the cement bond properly