What you need before you start

You will need a tire lever (usually two, sold as a pair), a replacement inner tube or a patch kit, and a bicycle pump. A tire lever is a flat plastic or metal tool that pries the tire bead — the edge of the tire — away from the rim so you can remove the tube. If you are patching instead of replacing, the patch kit contains sandpaper, adhesive, and patches; most kits cost three to five dollars and repair one to six punctures depending on the brand.

Before you buy a replacement tube, check the size printed on the side of your tire. It will look like "700x25c" or "26x2.0" — this number must match your new tube exactly. Bring a photo of your tire to the bike shop if you are unsure. A new inner tube costs five to fifteen dollars depending on the valve type and size.

If you do not have these tools at home, most bike shops will repair a flat for you for eight to twenty dollars, or you can walk or carry your bike to the nearest shop. Repairing it yourself takes fifteen to thirty minutes the first time, and five to ten minutes once you have done it twice.

Key Takeaways

  • Remove the wheel by opening the quick-release lever or unscrewing the axle nuts, then use a tire lever to pry the tire bead off the rim on both sides.
  • Pull out the old inner tube completely, then inspect the inside of the tire with your fingers to find and remove any thorns, glass, or sharp objects that caused the puncture.
  • Install a new tube by inserting the valve through the rim hole first, then tucking the tube evenly inside the tire all the way around before reseating the tire bead.
  • Inflate the tire to the pressure printed on its sidewall, checking that the tire bead is seated evenly on the rim as you pump.
  • Patching a tube works for small punctures but takes longer than replacement and may fail on the road; replacement is faster and more reliable for commuting.

Remove the wheel from the frame

Flip your 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 on the left side of the hub (the center of the wheel) by flipping it outward, then unscrew the bolt on the right side by hand or with a wrench until the wheel lifts out. If there is no quick-release, use an adjustable wrench or the correct socket size to unscrew both axle nuts.

For the rear wheel, shift the chain to the smallest cog first, then open the quick-release or unscrew the axle nuts the same way. Pull the derailleur (the mechanism that moves the chain) backward with your hand and lift the wheel up and out of the chain. The wheel should come free without force; if it does not, you may have missed a bolt or the quick-release is not fully open.

Remove the tire and inner tube

Lay the wheel flat on the ground. Insert a tire lever under the tire bead (the inner edge of the tire) at a point away from the valve, then pry the bead up and over the rim edge. Slide the lever around the rim to lift the entire bead off on one side — you may need two levers, one on each side of the first, to do this without pinching the tube. Once one bead is free, the tube will be loose inside the tire.

Unscrew the valve nut (the small nut at the base of the valve stem) by hand, then pull the entire inner tube out through the valve hole. Set it aside. You do not need to remove the second bead of the tire from the rim — you can install the new tube with one bead still seated.

Before you install a new tube, run your fingers slowly around the inside of the tire, feeling for thorns, glass shards, or sharp objects. Even a tiny piece of glass or a thorn left inside will puncture the new tube when ready. If you find something, remove it with tweezers or your fingers and discard it. Wipe the inside of the tire with a dry cloth if it is wet or muddy.

Install the new inner tube

Inflate the new tube slightly — just enough so it holds its shape and is not completely flat. This makes it easier to tuck into the tire evenly without twisting or pinching. Unscrew the valve nut on the new tube and insert the valve stem through the hole in the rim from the inside. Screw the valve nut back on by hand until it is snug, but do not over-tighten it.

Starting at the valve, tuck the tube evenly inside the tire all the way around the rim. Use your hands to smooth out any twists or bunches. Once the tube is seated, use your hands or a tire lever to press the tire bead back onto the rim, working your way around from the valve in both directions. The last section near the valve will be tight — this is normal. Press firmly and work the bead onto the rim with your palms rather than the lever to avoid pinching the new tube.

Inflate the tire to the correct pressure

Check the sidewall of the tire for the pressure range, printed in PSI (pounds per square inch). It will look like "80–100 PSI" or "50–65 PSI" depending on the tire width and type. Road bike tires are usually higher pressure (80–130 PSI), while mountain and hybrid tires are lower (30–65 PSI). Start at the lower end of the range if you are unsure.

Attach your pump to the valve and inflate slowly, stopping every few seconds to check that the tire bead is seating evenly on the rim. The bead should form a thin, even line where the tire meets the rim all the way around — if it bulges or dips, stop, deflate slightly, and reseat the bead by hand before continuing. Once the tire reaches the target pressure, remove the pump and screw the valve cap back on.

Reinstall the wheel on the frame

For the front wheel, open the quick-release lever, align the wheel with the fork, and slide the axle into the dropouts (the slots at the end of the fork). Close the quick-release lever firmly — it should require some pressure to flip closed. If it closes too easily, open it, screw the bolt on the right side a quarter turn tighter, and try again. The wheel should not spin freely side to side.

For the rear wheel, pull the derailleur backward, align the wheel with the chain, and slide the axle into the dropouts. The chain should rest on the smallest cog. Close the quick-release or tighten the axle nuts the same way as the front. Spin the wheel to make sure it does not rub on the brake pads or frame.

Patching instead of replacing

If you do not have a replacement tube, a patch kit can repair a small puncture. First, locate the hole by inflating the old tube and listening for air, or submerging it in water and looking for bubbles. Mark the hole with a pen if it is hard to see. Dry the tube completely and roughen the area around the hole with the sandpaper included in the kit — sand in a circular motion for about thirty seconds.

explore a thin, even layer of adhesive from the kit to the sanded area and wait the time specified on the kit (usually one to three minutes). Peel the foil backing from the patch and press it firmly onto the hole, holding it down for the time specified — usually two to three minutes. Once the adhesive sets, peel off the clear plastic layer. Inflate the tube slightly and test the patch by listening or submerging it again.

Patching works for punctures smaller than a quarter inch and for slow leaks, but it is slower than replacement and may fail while you are riding. If you patch a tube and it fails on the road, you will be stranded without a spare. Most riders carry a replacement tube and use patches only as a backup.

Frequently Asked Questions

What causes a flat tire?

The most common causes are thorns, glass, or sharp metal objects that puncture the tube. Pinch flats happen when the tire pressure is too low and the tube gets squeezed between the tire and rim — these show two small holes opposite each other. Valve leaks occur when the valve stem is cracked or the valve nut is loose. Slow leaks from small punctures may take hours or days to go flat.

Can I ride on a flat tire to get home?

Riding on a completely flat tire will damage the rim and the tire itself, costing more to replace. If you are close to home, walk or carry the bike instead. If the tire is only partially flat, you can ride slowly to the nearest bike shop, but inflate it as much as possible first.

How do I know which valve type my bike uses?

There are three types: Schrader (looks like a car tire valve, wider and shorter), Presta (thin and tall with a small nut at the top), and Dunlop (similar to Presta but slightly wider). Check your current tube or take a photo of your valve to the bike shop. The replacement tube must match exactly.

Why does my new tube keep going flat?

You likely missed a sharp object inside the tire — run your fingers around the inside again slowly and carefully. Another cause is the tire bead not seating evenly, which pinches the tube. Deflate, reseat the bead by hand, and reinflate slowly while watching for bulges or dips.

Should I replace the tire too, or just the tube?

Replace only the tube unless the tire itself is cracked, bulging, or has large cuts. A tire with a small puncture hole can be reused many times. If you see damage to the tire rubber itself, replace it at the same time as the tube to avoid another flat soon after.