What you need before you start
You will need a new inner tube that matches your wheel size and valve type, two tire levers (plastic or metal), and a pump. The tire lever is the most important tool — it lets you pry the tire bead away from the rim without pinching the new tube. You can buy a replacement tube at any bike shop or online for $8 to $20 depending on wheel size. Bring your old tube or wheel to the shop if you are unsure which size to buy.
Check your wheel size by looking at the sidewall of your tire. It will say something like 26", 27.5", 29", or 700c. Your valve type is either Schrader (looks like a car tire valve) or Presta (thinner, with a small locking nut at the top). Some tubes work with both; others are specific. A shop employee can match your old tube in under a minute if you bring it with you.
Key Takeaways
- You need a replacement tube that matches your wheel size and valve type, plus two tire levers and a pump.
- Remove the wheel from the bike, then use tire levers to pry one side of the tire bead off the rim and pull out the old tube.
- Insert the new tube starting at the valve, then work your way around the rim, making sure the tube sits evenly inside the tire.
- Reinstall the tire bead using your hands first, then tire levers if needed, and inflate slowly while checking that the bead seats properly.
- The whole job takes 10 to 15 minutes once you have done it once; your first time may take 20 to 30 minutes.
Remove the wheel and old tube
Flip the bike upside down so it rests on the handlebars and seat, or use a bike stand if you have one. For the front wheel, open the quick-release lever (or unscrew the axle nuts if your bike has them) and lift the wheel out of the fork. For the rear wheel, shift to the smallest chainring, open the quick-release, and pull the derailleur back to create slack in the chain, then lift the wheel out of the dropouts.
Once the wheel is off, let out any remaining air by pressing the valve. Insert a tire lever under the tire bead (the edge of the tire that sits on the rim) about 6 inches away from the valve. Pry gently until the bead lifts over the rim edge. Slide the lever around the rim to free one full side of the tire. You do not need to remove the tire completely — just enough to pull out the old tube.
Reach inside and pull the old tube out. Check the inside of the tire for thorns, glass, or sharp objects that may have caused the puncture. Run your fingers carefully along the inside surface and the rim tape. If you find anything, remove it. If you do not find the cause, the puncture may have been a pinch flat (caused by hitting a pothole or curb) or a slow leak from age.
Install the new tube
Inflate the new tube just enough so it holds its shape — about 10 to 20 percent of full pressure. This prevents twists and makes it easier to seat inside the tire. Start at the valve: insert the valve through the rim hole first, then work the tube around the inside of the tire with your hands, making sure it sits evenly and does not bunch up anywhere.
Once the tube is in place all the way around, begin pushing the tire bead back onto the rim with your hands. Start opposite the valve and work your way around in both directions. The last section near the valve will be tight — this is normal. If your hands cannot push the bead on, use a tire lever, but be very careful not to pinch the new tube. Insert the lever under the bead and pry gently, moving it a few inches at a time rather than trying to force a large section at once.
Inflate and check the seal
Once the tire bead is fully seated on the rim, attach your pump to the valve. Inflate slowly to about 20 to 30 percent of the tire's maximum pressure (check the sidewall for the range). Stop and look at the tire from the side — you should see a thin line where the bead meets the rim all the way around. If you see the tube bulging out anywhere, the bead is not seated properly. Let out air, reseat that section by hand or with a lever, and try again.
Once the bead looks even, inflate to the pressure recommended on your tire sidewall. For most road tires, that is 80 to 130 psi. For mountain bike tires, it is usually 30 to 50 psi. Check the bead one more time as you inflate — if it starts to bulge, stop and fix it before you reach full pressure. A bead that is not seated properly will fail quickly.
Reinstall the wheel
For the front wheel, lift it into the fork and close the quick-release lever (or tighten the axle nuts). Make sure the wheel is centered in the fork and spins freely. For the rear wheel, pull the derailleur back, lift the chain onto the smallest chainring, and slide the wheel into the dropouts. Close the quick-release and spin the wheel to make sure it does not rub the frame or brakes.
Flip the bike right-side up and take it for a short test ride. The tire should feel firm and responsive. If it feels soft or you hear a hissing sound, stop and check the valve — it may not be fully seated. If the tire feels right, you are done.
Common mistakes that cause problems
The most common error is twisting the tube as you install it. A twisted tube will pinch itself and puncture when you inflate. To avoid this, keep the tube relaxed and work it into place slowly, checking that it lies flat all the way around before you start pushing the tire bead back on.
The second mistake is not seating the bead properly before inflating to full pressure. If the bead is not seated, the tube will bulge out and fail within a few miles. Always stop at 20 to 30 percent pressure to check the bead visually, then inflate the rest of the way. The third mistake is using a tire lever too aggressively near the valve. The valve is the weakest part of the tube. If you pinch it with a lever, the new tube will leak. Use your hands as much as possible, and only use a lever as a last resort on the section opposite the valve.
When to patch instead of replace
If your tube has a small puncture (smaller than a pinhole) and you are at home with time to spare, a patch kit is cheaper than a new tube. Patch kits cost $3 to $8 and can fix one or two punctures. However, if the puncture is larger than a pinhole, the valve is damaged, or the tube has multiple holes, replacement is the only option.
On the road, always carry a spare tube — patching takes 10 to 15 minutes and requires the tube to be completely dry, which is not always possible. A spare tube gets you home quickly, and you can patch the old one later at your own pace.
Frequently Asked Questions
Can I use a tube from a different wheel size?
No. A tube that is too small will stretch and fail. A tube that is too large will bunch up inside the tire and pinch itself. Always match the wheel size exactly. If you are unsure, bring your wheel to a shop and ask them to confirm the size.
What is the difference between Schrader and Presta valves?
Schrader valves are wider and look like car tire valves. Presta valves are thinner and have a small locking nut at the top that you must unscrew before inflating. Some tubes work with both types; most are specific to one. Check your rim hole size — if it is wide, you need Schrader; if it is narrow, you need Presta.
Why does my new tube keep going flat?
The most common cause is a bead that is not seated properly, which allows the tube to bulge and pinch itself. The second cause is a sharp object still inside the tire — check the inside again carefully. The third cause is a twisted tube. If you installed it correctly and the bead is seated, the tube itself may be defective; take it back and ask for a replacement.
Do I need to remove the tire completely?
No. You only need to pry one side of the tire bead off the rim to pull out the old tube and insert the new one. Removing the tire completely takes longer and is not necessary for a tube replacement.
How tight should I inflate the tire?
Check the sidewall of your tire — it will show a pressure range, usually something like 80–130 psi for road bikes or 30–50 psi for mountain bikes. Inflate to somewhere in that range. Higher pressure gives a faster, harder ride; lower pressure gives more grip and comfort. Start in the middle and adjust based on how the bike feels.