What you need to do before you start
Replacing a bicycle tube means removing the old, damaged tube from inside your tire and installing a new one in its place. The tire itself stays on the wheel — you are only swapping out the inner tube. Most people can do this in 10 to 15 minutes once they have the right tools and a new tube that matches their wheel size.
Before you begin, you will need a new inner tube in the correct size for your bike. Check the sidewall of your current tire or look at your bike's manual to find the wheel diameter and width — common sizes are 26 × 2.0, 27.5 × 2.2, or 29 × 2.1 for mountain bikes, and 700 × 25c or 700 × 32c for road and hybrid bikes. Buy a tube marked for your exact size. You will also need two tire levers (plastic or metal tools that pry the tire away from the rim) and a pump. A patch kit is optional but useful to keep on hand for future flats.
Key Takeaways
- Remove the wheel from the bike, deflate the tire completely, and use tire levers to pry one side of the tire away from the rim so you can pull out the old tube.
- Check inside the tire for thorns, glass, or sharp objects that caused the flat, and remove them before installing the new tube.
- Insert the new tube into the tire, starting at the valve stem, then use your hands and tire levers to seat the tire bead back onto the rim evenly all the way around.
- Inflate the tire slowly to the pressure marked on the tire sidewall, checking that the tire bead stays seated and does not bulge or pinch the tube.
- Reinstall the wheel on the bike, making sure the quick-release or axle nuts are tight and the wheel spins freely without rubbing.
Remove the wheel and deflate the tire completely
Start by taking the wheel off the bike. If your bike has a quick-release lever on the hub, open it and unscrew the opposite side nut a few turns, then pull the wheel away from the frame. If your bike has bolt-on axles, use a wrench to loosen the nuts on both sides of the hub, then lift the wheel out. For the rear wheel, you may need to shift the chain onto the smallest cog first to create slack.
Once the wheel is off, press the valve stem (the small metal or plastic post where you pump air in) to release any remaining air. You should hear a hiss as the tire deflates. Push on the tire with your hand — it should feel soft and floppy, not firm. If air is still trapped, press the valve again until no more comes out.
Pry the tire away from the rim using tire levers
Insert a tire lever under the edge of the tire, about 6 inches away from the valve stem. Pry gently until the tire bead (the inner edge of the tire) lifts away from the metal rim. Once you have lifted a small section, hook the tire lever to a spoke to hold that section in place. Insert a second tire lever about 12 inches away and pry again, then hook it to another spoke.
Work your way around the wheel, lifting the tire bead a little at a time. You do not need to remove the entire tire — once you have lifted one side all the way around, you can reach in and pull out the old tube. Start at the valve stem and work the tube out of the tire, being careful not to pinch the tire bead with your fingers.
Inspect the tire for damage before installing the new tube
Before you put in the new tube, run your fingers slowly along the inside of the tire, feeling for thorns, glass shards, sharp rocks, or any other debris. This is the most common reason a new tube fails shortly after installation — the same object that punctured the first tube will puncture the second one if you do not remove it. If you find something, pull it out carefully. A small flashlight helps you see inside the tire.
Also check the rim tape — the strip of rubber or fabric that covers the spoke holes on the inside of the rim. If it is torn or missing, the spoke ends can puncture a new tube. If the tape is damaged, replace it before installing the new tube. Rim tape is inexpensive and comes in rolls sized to fit different wheel diameters.
Install the new tube and reseat the tire
Inflate the new tube just enough so it holds its shape — about 20 to 30 percent full. This makes it easier to position inside the tire without twisting or pinching. Insert the valve stem through the hole in the rim first, then work the tube into the tire all the way around, making sure it sits evenly and does not bunch up in any spot.
Now push the tire bead back onto the rim. Start at the valve stem and use your hands to roll the tire bead back into place, working your way around the wheel. The last section, opposite the valve, will be tight — this is normal. If you cannot push it on by hand, use a tire lever to help, but be very careful not to pinch the new tube. You should hear or feel a small pop as the last section snaps into place.
Inflate the tire to the correct pressure
Attach your pump to the valve stem and inflate slowly. Stop every few seconds to check that the tire bead is seating evenly on both sides of the rim. Look at the thin line where the tire meets the rim — it should be the same distance from the rim all the way around. If one section bulges outward or sits lower than the rest, stop, deflate, and reseat that section by hand before continuing.
Inflate to the pressure printed on the sidewall of the tire. Road bike tires typically call for 80 to 130 psi, while mountain bike tires usually need 30 to 50 psi. Do not guess — use a pump with a pressure gauge or check the pressure with a separate gauge after you finish. Overinflating can cause the tube to burst; underinflating makes the tire sluggish and more prone to pinch flats.
Reinstall the wheel on the bike
Lift the wheel back onto the bike frame. For the front wheel, center it in the fork and tighten the quick-release lever or axle nuts firmly — the wheel should not move side to side when you try to wiggle it. For the rear wheel, pull the derailleur back to create slack in the chain, set the wheel into the chain and frame, then tighten the quick-release or axle nuts. Make sure the chain sits on the smallest cog and does not rub.
Spin the wheel by hand to check that it turns freely and does not rub against the brake pads or frame. If it rubs, the wheel may not be centered — loosen the quick-release or axle nuts slightly, center the wheel, and tighten again. Once the wheel spins freely, you are done. Ride gently for the first few minutes to make sure the tire pressure feels right and the wheel stays true.
Frequently Asked Questions
How do I know what size tube to buy?
Look at the sidewall of your tire — it will show two numbers, like 26 × 2.0 or 700 × 32c. The first number is the wheel diameter in inches or millimeters, and the second is the tire width. Buy a tube labeled for that exact size. If you are unsure, take a photo of your tire sidewall to the bike shop and they can match it for you.
What if I pinch the new tube while putting the tire back on?
You will hear a loud pop or hiss. Deflate the tire, remove it again, and inspect the tube for a hole. If the hole is small, you can patch it with a patch kit. If it is large or you do not have a patch kit, you will need another new tube. To avoid pinching in the future, inflate the tube slightly before reinstalling the tire so it is firm enough to move out of the way of the tire levers.
Can I reuse the old tube if it just has a small hole?
Yes, if the hole is small and clean. Use a patch kit — clean the area around the hole with the sandpaper included in the kit, explore the adhesive, wait the time specified on the kit, then press the patch firmly onto the hole. Let it cure for the time listed before inflating. Patches work best on holes smaller than a pinhole; larger holes or tears are harder to repair reliably.
Why does my new tube keep going flat?
The most common reason is that you did not remove the object that caused the first flat. Run your fingers inside the tire again, feeling carefully for anything sharp. The second most common reason is that the rim tape is torn and a spoke is puncturing the tube. Check the rim tape and replace it if needed. A third possibility is that you are overinflating — check the pressure with a gauge and deflate slightly if it is above the tire's maximum.
Do I need to remove the tire completely to replace the tube?
No. You only need to pry one side of the tire away from the rim. Once the bead is lifted all the way around, you can reach in and pull out the old tube and install the new one without removing the tire entirely. Removing the whole tire takes longer and is usually unnecessary unless the tire itself is damaged or you are replacing the rim tape.