What you need before you start

A flat tire is fixable on the spot with three things: a tire lever (a plastic or metal tool that pries the tire off the rim), a patch kit or replacement inner tube, and a pump. You may already have these in a saddlebag or backpack. If not, buy them before you need them—a patch kit costs a few dollars and fits in a pocket.

Patch kits work for small punctures (a thorn, a piece of glass, a nail hole). Replacement tubes are faster and more reliable, especially if you are far from home or the puncture is large. Many riders carry both: a patch kit as backup and a spare tube as the main repair. A hand pump or frame pump is essential—you cannot patch or replace a tube without reinflating the tire afterward.

Before you start, find the puncture. Spin the wheel slowly and look for the object (a thorn, glass, or metal shard) still stuck in the tire. If you see it, mark the spot with your finger or a piece of tape so you know where to look inside the tire. If you do not see anything, you will find the hole when you remove the tube.

Key Takeaways

  • Remove the wheel from the frame, then use a tire lever to pry one edge of the tire off the rim so you can pull out the inner tube.
  • Locate the puncture by looking for a sharp object in the tire or by feeling for a hole in the tube with your fingers.
  • Either patch the hole with a patch kit (which requires drying time) or replace the tube with a spare one you carry with you.
  • Reinstall the tube inside the tire, seat the tire bead back onto the rim, and pump the tire to the pressure marked on the sidewall.
  • Check that the tire is seated evenly all the way around the rim before riding, because an uneven seat can cause another flat.

Removing the wheel and tire

First, remove the wheel from the frame. If you have a quick-release lever on the hub (the center of the wheel), open it and unscrew the opposite nut by hand until the wheel lifts free. If you have bolt-on axles, use a wrench to loosen both bolts, then unscrew them by hand and lift the wheel out. Lay the wheel flat on the ground.

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 stem. Pry the bead up and 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 entire tire—just one side. Once one bead is free, you can pull the inner tube out from under the tire.

Pull the valve stem out of the rim hole first, then slide the tube out from under the tire. Set the tube aside. Inspect the inside of the tire with your fingers, running them slowly along the inner surface. Feel for sharp objects, thorns, or rough spots. If you find something, remove it. This step prevents a second flat when ready after you repair the first one.

Patching the tube versus replacing it

If you are using a patch kit, dry the tube completely and locate the hole. Most patch kits include sandpaper—roughen the area around the hole, then explore the adhesive (if the kit requires it) and press the patch firmly onto the hole. Hold it for the time the kit specifies, usually 30 seconds to 2 minutes. Patch kits work well for small punctures, but they require you to wait and they sometimes fail if the surface is wet or dirty.

Replacing the tube is faster and more reliable. Remove the new tube from its packaging, inflate it slightly (just enough so it holds its shape), and insert the valve stem into the rim hole. Tuck the tube evenly under the tire all the way around the wheel, making sure it does not twist or bunch up. This matters—a twisted tube can pinch and create a new flat.

Reinstalling the tire on the rim

Starting opposite the valve stem, use your hands to roll the tire bead back onto the rim. Work your way around the wheel in both directions, pushing the bead down and under the rim edge. 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 roll the final section of bead onto the rim.

Once the tire is seated, check that the bead sits evenly all the way around. Look at the rim from the side and make sure the tire edge is the same distance from the rim all the way around. If one section bulges out or sits too high, the tire is not seated correctly. Deflate it slightly, work that section by hand until it sits flush, then reinflate. An uneven seat will cause the tire to fail again.

Pumping the tire to the correct pressure

Look at the sidewall of the tire. It will show a pressure range, usually something like "80–100 psi" (pounds per square inch) for a road bike or "30–50 psi" for a mountain bike. Pump the tire to the middle or upper end of that range. Use a pump with a gauge so you can see the pressure as you pump. Hand pumps are slower than floor pumps, but they work fine for a roadside repair.

Attach the pump head to the valve stem firmly—it should not leak air around the connection. Pump slowly and steadily. Check the gauge every few strokes. Stop when you reach the target pressure. Detach the pump and check the valve stem—it should not hiss or leak. If it does, reattach the pump and tighten the connection.

Reinstalling the wheel on the frame

Lift the wheel and align the axle with the frame dropouts (the slots where the axle sits). For a quick-release wheel, open the lever, slide the axle into the dropouts, close the lever, and tighten the opposite nut by hand until snug. For a bolt-on wheel, slide the axle in and hand-tighten both bolts, then use a wrench to tighten them firmly.

Spin the wheel to make sure it does not rub against the brake pads or frame. If it does, the wheel is not centered—remove it and reseat the axle. Once the wheel spins freely, you are ready to ride. Before you go, squeeze the tire with your hand to confirm it feels firm and holds pressure.

When to call a professional or replace the tire

If the puncture is very large (bigger than a quarter inch), the patch kit or spare tube will not hold. If the tire sidewall is torn or the bead is damaged, the tire cannot be repaired and must be replaced. If you cannot locate the puncture after inspecting the tube and tire, the leak may be at the valve stem—in that case, replace the tube.

If you are uncomfortable removing the wheel or working with the tire, a bike shop can repair a flat for a small fee, usually $10 to $20. Many shops will also show you how to do it yourself if you ask. Learning to patch or replace a tube takes 10 minutes the first time and becomes automatic after that.

Frequently Asked Questions

Can I ride on a patched tube right away or do I have to wait?

Patch kits require drying time—usually 30 seconds to 2 minutes depending on the brand. Check your kit's instructions. If you are in a hurry, use a spare tube instead. A patched tube works fine once it is dry, but riding before the adhesive sets can cause the patch to fail.

What if I get a flat and I do not have a pump?

You cannot reinflate the tire without a pump. Carry a hand pump or a CO2 cartridge (a small pressurized canister that inflates a tire in seconds). A bike shop or gas station may have a floor pump you can use, but it is not reliable. A hand pump weighs almost nothing and costs $10 to $20.

How do I know if the puncture is in the tube or the tire?

Inflate the tube by itself (outside the tire) and listen or feel for air leaking. If you hear or feel air, the hole is in the tube. If the tube holds air, the problem is the tire—check inside the tire for a sharp object or a hole in the rubber itself.

Can I patch a tube that has a hole near the valve stem?

Patch kits work best on the side of the tube away from the valve. If the hole is very close to the valve stem, patching is difficult and often fails. Replace the tube instead. Valve stem leaks usually mean the tube itself is faulty and should be replaced.

What should I do with the old tube after I replace it?

If the tube is patched and holds air, keep it as a spare. If it is damaged or the patch failed, recycle it at a bike shop or a recycling center that accepts rubber. Do not throw it in the trash—inner tubes take decades to decompose.