How to change a bike tire and fix a flat
Every rider should be able to fix a flat. It's a ten-minute job once you've done it a couple of times, and it gets you home instead of walking. Here's the whole process.
What you'll need
- A spare tube (the right size — it's printed on your tire sidewall, e.g. 700×25c or 29×2.2)
- Two tire levers
- A pump or CO₂ inflator
Step 1: Remove the wheel
Release the brake if needed (rim brakes), open the quick-release or undo the thru-axle, and lift the wheel out. For the rear, shift to the smallest cog first to make it easier.
Step 2: Get the tire off
- Let out any remaining air completely.
- Push one bead of the tire toward the center of the rim to loosen it.
- Hook a tire lever under that bead, clip it to a spoke, then run a second lever around to free one side of the tire.
- Pull the tube out.
Step 3: Find the cause (don't skip this)
If you fit a new tube without finding what caused the flat, you'll just puncture again. Run your fingers carefully around the inside of the tire and inspect the outside for a thorn, shard of glass, or cut. Check the rim tape is intact and covering the spoke holes. Remove anything you find.
Step 4: Fit the new tube
- Put just enough air in the tube to give it shape — it's much easier to handle and less likely to get pinched.
- Seat the valve through the valve hole, then tuck the rest of the tube up inside the tire all the way around.
- Work the tire bead back onto the rim with your thumbs. Try to do the last section by hand — levers here often pinch the tube and cause an instant re-flat.
Step 5: Check and inflate
- Before fully inflating, push the tire side to side around the whole rim to make sure the tube isn't pinched under the bead.
- Inflate gradually to the pressure range printed on the tire sidewall, checking the bead seats evenly (there's usually a molded line to watch).
- Refit the wheel, close the brake, and you're rolling.
When flats keep happening
An occasional flat is bad luck. Frequent flats usually mean the tire itself is worn thin or cut — see how often to replace your tires. Tracking tire mileage gives you a nudge to replace them before they start letting debris through. For the rest of the bike, here's a full maintenance schedule by mileage.