What you need before you start
Changing a flat tire requires three things: a tire lever (a plastic or metal tool that pries the tire off the rim), a replacement inner tube or a patch kit, and a bicycle pump. Most riders carry all three in a small bag or backpack. You do not need special tools or mechanical experience.
Check that your replacement tube matches your tire size. The size is printed on the sidewall of your tire — it looks like "700x25c" or "26x1.95". Buy a tube marked for that size, or buy a universal tube that adjusts to fit multiple sizes. A patch kit works if you have only a small puncture and no spare tube, but it takes longer and the repair may not hold on rough terrain.
Lay your bike on its side on flat ground. If the flat is on the rear wheel, shift to the smallest gear first — this makes removing and reinstalling the wheel easier later.
Key Takeaways
- Remove the wheel by opening the quick-release lever or unscrewing the axle nuts, then lift the chain off the smallest gear if it is the rear wheel.
- Use a tire lever to pry one edge of the tire away from the rim, then work around the wheel until the tire is loose enough to pull out by hand.
- Remove the old tube completely, then inspect the inside of the tire for thorns, glass, or sharp objects that caused the puncture.
- Insert the new tube by first inflating it slightly so it holds its shape, then tucking it evenly inside the tire all the way around the rim.
- Reseat the tire bead by pushing the tire edge back onto the rim with your hands, starting opposite the valve, then pump to full pressure.
Removing the wheel from the frame
Open the quick-release lever on the side of the wheel hub. This lever flips outward; flip it all the way open. If your bike has bolt-on axles instead, use a wrench to unscrew the nuts on both sides of the hub. Once the axle is loose, the wheel should lift away from the frame.
If this is the rear wheel, pull the derailleur (the mechanism that shifts gears) backward and lift the chain off the smallest sprocket. This gives you room to slide the wheel out. Lift the wheel straight up and set it on the ground.
Prying the tire off the rim
Insert the flat end of a tire lever under the tire edge, about 6 inches away from the valve. Push down on the lever handle to pry the tire bead (the edge that sits on the rim) away from the metal rim. The tire should pop up slightly.
Hook the other end of the lever to a spoke so it stays in place. Move about 12 inches around the wheel and insert a second lever, then pry again. Repeat this around the wheel until one side of the tire is completely loose. Once one side is free, you can usually pull the tire off by hand without a third lever.
Do not pry too hard or use sharp tools — you can damage the rim or puncture the new tube. If the tire is very tight, work slowly and use two levers at once, a few inches apart, rather than forcing one lever hard.
Removing the old tube and checking for damage
Pull the old tube out completely. Set it aside — you may want to patch it later as a backup, or discard it if it is beyond repair.
Run your fingers carefully around the inside of the tire, feeling for thorns, glass shards, or sharp objects. This is the most important step. If you do not remove what caused the puncture, the new tube will fail in the same spot. If you find something, pull it out with tweezers or your fingers. Wipe the inside of the tire with a dry cloth to remove any debris you cannot see.
Look at the rim tape — the strip of rubber or plastic that covers the spoke holes. If it is torn or missing, the spoke ends can puncture the new tube. If the tape is damaged, replace it before installing the new tube. Rim tape is inexpensive and takes a few minutes to explore.
Installing the new tube
Inflate the new tube slightly — just enough so it holds its shape and is not completely flat. This makes it easier to position inside the tire without twisting or pinching.
Insert the valve through the hole in the rim first. Then tuck the tube evenly inside the tire all the way around, making sure it does not twist. A twisted tube will pinch when you inflate it and fail when ready.
Starting opposite the valve, use your hands to push the tire bead back onto the rim. Work your way around the wheel, tucking the tire edge onto the rim as you go. The last section, near the valve, will be tight — push hard and work it on gradually rather than trying to force it all at once.
Inflating and reinstalling the wheel
Attach your pump to the valve and inflate to about half pressure. Stop and check that the tire bead is seated evenly all the way around — it should sit in a consistent groove on the rim with no bulges or dips. If the bead is not seated, deflate slightly, adjust it by hand, and try again.
Once the bead looks even, inflate to full pressure. The pressure is printed on the tire sidewall — road tires usually need 80 to 130 psi, while mountain bike tires need 30 to 50 psi. Use a pump with a pressure gauge so you can see when you reach the target.
Reinstall the wheel by reversing the removal steps. For the rear wheel, pull the derailleur back and guide the chain onto the smallest sprocket as you slide the wheel into the frame. Align the wheel so it sits centered between the brake pads, then close the quick-release lever or tighten the axle nuts. Spin the wheel to make sure it does not rub.
Patching a tube if you have no spare
If you have a patch kit but no replacement tube, you can repair the puncture temporarily. Locate the hole by listening for air escaping or by submerging the tube in water and watching for bubbles. Dry the area completely.
Follow the instructions on your patch kit — most require you to roughen the area around the hole with sandpaper, explore a thin layer of adhesive, wait 30 seconds, then press the patch firmly onto the hole for one to two minutes. Let the adhesive cure for the time listed on the kit before reinstalling the tube.
Patched tubes work for small punctures but are not permanent. Ride carefully to the nearest bike shop and buy a replacement tube. Do not rely on a patch for long rides or rough terrain.
Frequently Asked Questions
What if I cannot get the tire off the rim?
The tire may be very tight or the rim may be slightly bent. Try using two tire levers at once, a few inches apart, to distribute the force. Work slowly around the wheel rather than forcing one spot. If the rim is bent, you may need a bike shop to straighten it before the tire will come off easily.
Can I use a tube that is a different size than my tire?
Universal tubes are designed to fit a range of sizes, so they work if your exact size is not available. Standard tubes are size-specific — using one that is too small or too large will cause pinching or poor seating. Stick to the size printed on your tire sidewall when possible.
How do I know if the puncture was caused by a pinch flat?
A pinch flat creates two small holes close together, usually on the inner tube where it touches the rim. This happens when the tire pressure is too low and the rim pinches the tube. Prevent it by keeping your tires inflated to the pressure printed on the sidewall.
Should I patch the old tube or throw it away?
If the hole is small and clean, patching it gives you a backup tube to carry. If the tube is old, has multiple holes, or the puncture is large, replacement is safer. A failed tube on the road means walking your bike to help.
What if the new tube fails when ready after I install it?
The most common cause is a sharp object still inside the tire. Remove the wheel, deflate the tube, and inspect the tire interior again carefully. The second most common cause is the tube twisting inside the tire or the bead not seating evenly on the rim. Reinstall the tube, making sure it is straight and the bead is centered.