What you need before you start

Replacing a bike inner tube takes about 15 to 30 minutes once you have the right tools. You will need a new inner tube that matches your wheel size (check the sidewall of your current tire for the size — it looks like 700x25c or 26x1.95), two tire levers to pry the tire off the rim, and a pump. A patch kit is optional but useful if you get a flat while you are out and do not have a spare tube with you.

Before you buy a replacement tube, write down your wheel size and tire width. Inner tubes come in specific sizes, and buying the wrong one means a wasted trip back to the shop. Most bike shops will let you check the size on the shelf before you pay, or you can take a photo of your tire sidewall and show it to the staff.

You do not need special tools beyond the tire levers. Many people use a flathead screwdriver in a pinch, though actual tire levers are cheaper and less likely to damage your rim. If your bike has rim brakes, you may also need to release the brake cable to get the wheel off — check your bike's manual or ask at the shop when you buy the tube.

Key Takeaways

  • Buy a replacement tube that matches your wheel size, which is printed on the sidewall of your current tire.
  • You need only tire levers, a pump, and the new tube — no special skills or expensive tools required.
  • Remove the wheel, pry off one side of the tire with the levers, pull out the old tube, and slide the new one in before reseating the tire.
  • Inflate slowly and check that the tire bead sits evenly on the rim before you ride, or the tube will pinch and flat again.
  • If you find a hole in the old tube, inspect the inside of the tire for thorns, glass, or sharp rim tape that caused the flat.

Remove the wheel from your bike

Flip your bike upside down so it rests on the handlebars and seat, or use a bike stand if you have one. This keeps your hands free and the wheel at a comfortable working height. If your bike has quick-release levers on the wheel axle, open them by flipping the lever outward — they should move freely without tools. If your bike has bolt-on axles, use an appropriately sized wrench to loosen the nuts on both sides.

Once the axle is loose, lift the wheel out of the frame. On the rear wheel, you may need to pull the derailleur back and lift the chain out of the way first. Set the wheel on a clean surface so the tire does not roll away while you work.

Pry the tire off the rim

Insert a tire lever under the edge of the tire, about 6 inches away from the valve stem. Push down on the lever to pry the tire bead (the edge that sits on the rim) up and over the rim edge. Once you have lifted one section, hook the lever to a spoke so it stays in place. Insert a second lever about 12 inches away and repeat, then work your way around the rim until one side of the tire is completely off.

You do not need to remove the entire tire — just one side. Leave the other side seated on the rim. This makes it much easier to slide the new tube in without pinching it. If the tire is very tight, you can use a third lever or work more slowly around the rim rather than trying to force it all at once.

Remove the old tube and inspect the tire

Once one side of the tire is off, pull out the old inner tube. Before you throw it away, look for a hole or puncture — this tells you what went wrong. A small hole usually means a thorn or piece of glass got through the tire. A pinch flat (two small holes close together) means the tire pressure was too low when you hit a bump.

Now inspect the inside of the tire carefully. Run your fingers slowly along the inner surface, feeling for thorns, glass shards, or sharp edges. Pay special attention to the area around the hole in the old tube — that is where the problem object is likely to be. If you find something, remove it. Also check the rim tape (the strip that covers the spoke holes) for damage or missing sections. If the rim tape is torn or missing, the spoke ends can puncture a new tube, and you will have the same problem again.

If the rim tape is damaged, wrap it with electrical tape or buy replacement rim tape from a bike shop before you install the new tube. This takes only a few minutes and prevents a repeat flat.

Install the new inner tube

Inflate the new tube slightly — just enough so it holds its shape and does not fold in on itself. This makes it much easier to seat properly in the tire. Slide the valve stem through the rim hole first, then work the tube around the inside of the tire, making sure it sits evenly and does not twist.

Starting opposite the valve stem, use your hands to push the tire bead back onto the rim. Work your way around in both directions, using steady pressure rather than force. The last section, near the valve stem, will be tight — this is normal. Push the valve stem up into the tire to create slack, then push the final section of bead onto the rim.

Inflate and check the seal

Attach your pump to the valve stem and inflate slowly to about half pressure. Stop and look at the tire from the side — the bead should sit evenly in the rim all the way around, with no bulges or dips. If one section looks loose or the bead is not seated, let out the air, work that section back onto the rim by hand, and try again.

Once the bead looks even, inflate to your target pressure. Check the sidewall of the tire for the recommended pressure range — it is usually between 80 and 130 psi depending on the tire width and your weight. Inflate to the middle of that range as a starting point. Squeeze the tire with your hand to feel the firmness, then ride a short distance on flat ground to make sure everything feels right before you take it on the road.

Reinstall the wheel on your bike

Lift the wheel back into the frame and align the axle with the dropouts (the slots on the frame that hold the wheel). For the rear wheel, pull the derailleur back and guide the chain onto the smallest cog. Tighten the quick-release lever or the axle bolts until the wheel is snug and does not move side to side.

Spin the wheel to make sure it does not rub on the brake pads or frame. If it does, the wheel may not be centered — loosen the axle slightly, center the wheel by eye, and tighten again. Once the wheel spins freely, reconnect the brake cable if you had to release it, and test the brakes before you ride.

Frequently Asked Questions

What size inner tube do I need?

Check the sidewall of your tire for the size — it is printed in large numbers and looks like 700x25c or 26x1.95. The first number is the wheel diameter, the second is the tire width. Buy a tube labeled for that exact size. If you are between sizes, tubes have a small range they cover, so the shop staff can tell you if a tube will work for your tire.

Can I patch the old tube instead of replacing it?

Yes, if the hole is small and not near the valve stem. Patch kits cost a few dollars and work well for roadside repairs. However, if the tube has a pinch flat (two holes), a large tear, or a hole near the valve, replacement is faster and more reliable. Most people carry a spare tube for rides and use patches only when they are stranded.

Why does my new tube keep going flat?

The most common cause is something sharp still inside the tire — a thorn, glass, or damaged rim tape. Inspect the tire and rim carefully before you install the new tube. The second cause is pinching: if the tire bead is not seated evenly on the rim, the tube gets pinched when you ride and flats again. Inflate slowly and check the bead all the way around before you ride.

Do I need to remove the entire wheel to replace the tube?

Yes, you need to remove the wheel to access the tire. On the front wheel this takes 30 seconds. On the rear wheel it takes a bit longer because you have to move the chain out of the way, but it is still straightforward. Some people try to replace a tube without removing the wheel, but this makes it much harder to seat the bead properly and usually results in a repeat flat.

What pressure should I inflate the tube to?

Check the sidewall of your tire for the recommended range — it is usually printed in both psi and bar. Inflate to the middle of that range as a starting point. Narrower tires (road bikes) typically run 80 to 130 psi, while wider tires (mountain bikes) run 30 to 50 psi. You can adjust slightly up or down based on how the bike feels when you ride.