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, usually written as 26", 27.5", 28", or 29" for mountain and road bikes), two tire levers, and a pump. Tire levers are flat metal or plastic tools that pry the tire bead—the edge of the tire—away from the rim so you can remove the old tube.

Before you buy a replacement tube, write down your wheel size and tire width. A tube labeled 700c × 23–28mm, for example, fits a 700c wheel and works with tires between 23mm and 28mm wide. Buying the wrong size means the tube will either be too loose (and pinch when you inflate it) or too tight (and burst). Most bike shops will match your old tube if you bring it in, or you can photograph the sidewall and text the image to a shop.

Key Takeaways

  • Remove the wheel from the bike frame using the quick-release lever or wrench, then deflate the tire completely before prying off the tire with two tire levers.
  • Pull out the old inner tube and inspect the inside of the tire for thorns, glass, or sharp objects that punctured it, because replacing the tube without removing the cause will result in another flat.
  • Insert the new tube by first inflating it slightly (just enough so it holds its shape), then seating it evenly inside the tire before reinstalling the tire bead onto the rim.
  • Inflate the tire to the pressure printed on the sidewall, checking that the tire bead is seated evenly on both sides of the rim as you pump.
  • Reinstall the wheel on the frame, making sure the quick-release or axle nuts are tight enough that the wheel does not spin freely by hand.

Remove the Wheel and Deflate the Tire

Flip the bike upside down so it rests on the handlebars and seat, or use a bike stand if you have one. Locate the quick-release lever on the wheel axle (a small silver lever on the side of the hub) or the axle nuts if your bike has bolt-on wheels. If you have a quick-release, flip the lever outward to open it, then unscrew the opposite nut by hand until the wheel lifts free. If you have axle nuts, use a wrench (usually 15mm) to loosen both nuts, then unscrew them by hand and set them somewhere you will not lose them.

Once the wheel is off, press the valve on the inner tube to release all air. The valve is the small metal or plastic stem sticking out of the tire. Press it firmly until you hear air hissing out and the tire goes completely flat. A flat tire is much easier to work with because the tire bead will peel away from the rim without fighting you.

Pry Off the Tire and Remove the Old Tube

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. Do not force it—if it resists, deflate the tire more or work the lever around the tire in smaller sections. Once you have lifted one section, insert the second tire lever about 12 inches away and pry again. Work your way around the wheel, spacing the levers out so you are lifting the bead gradually rather than all at once.

When one side of the tire is completely off the rim, reach inside and pull out the old inner tube. Set it aside—you may want to inspect it later to see where the puncture was. Now peel the other side of the tire off the rim using the same lever technique. Once both sides are off, the tire will hang loose around the rim.

Inspect the Tire for the Cause of the Puncture

Run your fingers slowly along the inside surface of the tire, feeling for thorns, glass shards, or sharp metal. This step is critical: if you skip it and install a new tube without removing what caused the first puncture, the new tube will fail within a few miles. Work your way all the way around the tire, paying special attention to the areas where the puncture was located on the old tube.

If you find a thorn or piece of glass, mark the spot on the outside of the tire with a pen so you can inspect that area of the tire for damage. Small thorns sometimes leave holes in the rubber that will puncture a new tube again. If the hole is larger than a pinprick, the tire itself may need to be replaced, not just the tube. If you cannot find anything sharp, the puncture may have been caused by a pinch flat (the tube got squeezed between the tire and rim, usually from hitting a pothole), in which case a new tube is all you need.

Install the New Inner Tube

Inflate the new tube just enough so it holds its shape—about 20 to 30 percent full. A tube that is too soft will fold and pinch when you reinstall the tire; a tube that is too firm will be hard to fit inside the tire. You should be able to squeeze the tube slightly with your hand, but it should not collapse completely.

Insert the valve stem through the valve hole in the rim first. Then work the tube into the tire, making sure it sits evenly all the way around and does not twist or bunch up. Tuck the tube under the tire bead as you go, working your way around the wheel. The tube should lie flat and centered inside the tire, not pinched against the rim or folded over itself.

Reinstall the Tire Bead onto the Rim

Starting opposite the valve, push the tire bead back onto the rim using the heel of your hand. Work your way around the wheel in both directions, pushing the bead down and inward so it seats on the rim. As you get closer to the valve, the bead will become harder to push on because the tube is taking up more space. Push firmly but do not use the tire levers to force it—if the bead will not go on by hand, deflate the tube slightly and try again.

Once the entire bead is seated on the rim, check that the tube is not pinched. Look at the tire from the side and make sure the bead sits evenly on both sides of the rim. If one side is higher than the other, the tube may be caught under the bead. Deflate slightly, work that section loose, and reseat it.

Inflate the Tire to the Correct Pressure

Check the sidewall of the tire for the recommended pressure range, usually printed as something like "80–100 psi" or "2.5–3.0 bar." Start pumping, and as the tire inflates, watch the bead on both sides to make sure it stays seated evenly on the rim. If one side bulges outward while the other stays tight, stop, deflate, and reseat that section before continuing.

Inflate to the lower end of the recommended range first, then check the bead one more time. Once you are confident the bead is seated correctly, inflate to your target pressure. Most road bike tires go to 80–100 psi, while mountain bike tires are typically 30–50 psi depending on the width and terrain. A higher pressure gives you less rolling resistance on pavement; a lower pressure gives you more grip on dirt.

Reinstall the Wheel on the Frame

Lift the wheel and align it with the frame dropouts (the slots where the axle sits). For the rear wheel, make sure the chain is on the smallest cog and the derailleur is pulled back so the wheel slides in easily. Slide the axle all the way into the dropouts until it stops.

If you have a quick-release, close the lever by flipping it inward. The lever should be tight enough that you cannot move it by hand without effort, but not so tight that you need to use a wrench. If the lever is too loose, open it, tighten the opposite nut by a quarter turn, and close the lever again. If you have axle nuts, thread them back on by hand, then use a wrench to tighten them firmly—they should not move when you try to wiggle the wheel.

Spin the wheel to make sure it does not rub on the brake pads or frame. If it does, the wheel may not be seated all the way into the dropouts. Lift the wheel slightly and try again. Once the wheel spins freely, you are done.

Frequently Asked Questions

What size inner tube do I need?

Check the sidewall of your tire for the size, usually written as 26", 27.5", 28", or 29" for the wheel diameter, followed by the tire width in millimeters. A tube labeled 700c × 23–28mm fits a 700c wheel and works with tires 23mm to 28mm wide. When in doubt, bring your old tube or a photo of the sidewall to a bike shop and they will match it for you.

Can I patch the old tube instead of replacing it?

Yes, if the puncture is small and in the tube body (not near the valve). Patch kits are inexpensive and work well for roadside repairs. However, if the tube has multiple punctures, a large hole, or damage near the valve, replacement is faster and more reliable. Many riders carry a patch kit as a backup but replace the tube at home.

What if the tire bead will not go back on the rim?

Deflate the tube a bit more and try again. The tube takes up space inside the tire, and if it is too firm, the bead will not seat. You can also try working the bead on in smaller sections rather than all at once, pushing it down with the heel of your hand instead of your fingers. If the bead still will not go on, the tire may be too small for the rim, which means you need a different tire.

How do I know if my new tube is the right size?

The tube should fit snugly inside the tire without bunching or twisting. When you inflate it, it should fill the tire evenly without bulging in one spot or leaving gaps. If the tube is too small, it will not fill the tire properly. If it is too large, it will bunch up and pinch when you reinstall the tire bead.

Why did my tube puncture in the first place?

The most common causes are thorns or glass on the road, pinch flats from hitting a pothole or curb, or a sharp edge inside the tire or rim. Always inspect the inside of the tire before installing a new tube. If you find a thorn or glass, remove it. If you keep getting pinch flats, your tire pressure may be too low—check the sidewall and inflate to the recommended range.