Sooner or later, every cyclist gets a flat tire. It can happen on the way to work, on a trail or in the garage after the bike has sat for a while. Fixing it yourself is easier than it looks, takes about fifteen minutes with practice and saves a long walk home.
This guide covers the tools you need, how to remove the wheel, find the cause, patch or replace the tube and get back on the road. It assumes a standard tire with an inner tube; tubeless tires are covered briefly at the end.
What you need
- A spare inner tube in the right size (printed on the tire sidewall, for example 700x28c or 29×2.2) with the right valve type (Presta or Schrader).
- A patch kit, as a backup or for repairs at home.
- Two or three plastic tire levers.
- A pump or CO2 inflator that fits your valve.
- A multi-tool, if your wheels use bolts rather than quick-release levers. A compact Motorcycle/Bicycle Multi-Tool covers the common sizes.
Our Bike Survival Kit post lists everything worth carrying on every ride.
Step 1: Remove the wheel
Shift to the smallest rear cog if the flat is on the back wheel, which makes removal easier. Open the brake if you have rim brakes. Then open the quick-release lever or thru-axle, or loosen the axle nuts, and take the wheel out. For the rear wheel, pull the derailleur back slightly so the chain clears the cassette.
Step 2: Let out any remaining air and remove one side of the tire
Remove the valve cap and press the valve to release any air (on a Presta valve, unscrew the small tip first). Push the tire bead toward the center of the rim all the way around; this gives you slack. Hook a tire lever under the bead opposite the valve, pull it over the rim and clip the lever to a spoke. Insert a second lever a few inches along and slide it around the rim until one side of the tire comes off.
Step 3: Remove the tube and find the cause
Pull the tube out, pushing the valve through the rim last. Inflate it a little and listen or feel for escaping air. You can also pass it through a bowl of water and look for bubbles. Note where the hole is, then check the matching spot on the tire. Run your fingers carefully around the inside of the tire to find glass, thorns or wire, and remove anything you find. Also check the rim tape, which should cover every spoke hole.
Two small holes side by side, often called a “snake bite,” usually mean the tire pressure was too low and the tube was pinched against the rim.
Step 4: Patch or replace the tube
On the roadside, the fastest fix is a new tube. Keep the punctured one and patch it later at home:
- Roughen the area around the hole with the sandpaper in the patch kit.
- Apply a thin layer of glue and wait until it turns clear and tacky (for glueless patches, skip this).
- Press the patch firmly onto the hole and hold it for a minute or two.
- Let it cure before you inflate.
Step 5: Fit the new tube
Inflate the tube just enough to give it shape. Push the valve through the rim hole, then tuck the tube inside the tire all the way around, making sure it is not twisted.
Step 6: Put the tire back on
Starting at the valve, push the bead back over the rim with your thumbs, working both ways around the wheel. The last section is the hardest. Push the bead already on the rim into the center channel to gain slack, and use your palms to roll the last part on. Avoid using tire levers to refit if you can, because they can pinch the new tube.
Before inflating, go around the tire and push it aside to check that no tube is caught between the tire bead and the rim.
Step 7: Inflate and check
Inflate the tire part way, check that the bead sits evenly on both sides (most tires have a molded line just above the rim), then inflate to the pressure printed on the sidewall. Spin the wheel to check for wobbles or bulges, refit it in the frame, close the brake and check that the wheel is secure before riding.
Fixing a flat at dusk or on the roadside
Move well off the road before you start, and stay visible. A bright light such as the Fenix BC15R Lightweight Rechargeable Bicycle Light doubles as a work light when it gets dark. If you cannot fix the flat, it is usually safer to walk the bike to a safe spot than to ride on a flat tire, which can damage the rim.
Tubeless tires
Tubeless tires use liquid sealant that plugs most small punctures on its own. For larger holes, a tubeless plug tool can seal the gap. If that fails, you can remove the valve, fit a regular inner tube and ride home.
How to avoid the next flat
Check tire pressure regularly, replace worn tires and avoid riding through glass and debris. Our post on bicycle tire flat prevention tips covers more ways to cut down on punctures.
Frequently asked questions
Can I ride on a flat tire?
Only very slowly and for a short distance. It can damage the tire and rim and makes the bike hard to control.
Patch or new tube?
A new tube is faster on the road. Patches work well for small holes and save money.
How do I know my tube size?
Check the tire sidewall for the size and match the valve type on your rim.
We run the NicheStuff store; some links in this post go to products we sell.