Fixing a Flat Tire (Tube Replacement)

Tools Needed: Tire levers (2 levers recommended, plastic ones are safest for your rims), a replacement inner tube of the correct size (or a patch kit as backup), a pump or CO₂ inflator, and if your bike has bolt-on axles, a wrench that fits (most modern bikes have quick-release or thru-axles that don’t need a separate tool). For rim brakes, you may need to release the brake to remove the wheel.

Step-by-Step Guide:

1. Remove the Wheel: If it’s the rear wheel, shift your gears to the smallest rear cog (hardest gear) before removing – this puts least tension on the chain and makes it easier to take the wheel off. Open your brake release if you have rim brakes (flip up the lever on a road caliper or undo the noodle on a V-brake) so the tire can pass the pads. Open the quick-release lever or thru-axle: on a quick-release, flip the lever open and unscrew slightly if needed until the wheel can drop out. For thru-axle, turn the axle lever or use an Allen key to unscrew and slide it out. Carefully pull the wheel out of the frame/fork.

2. Deflate Completely: If the tire isn’t already fully flat, let out the remaining air. Unscrew the valve cap and press the valve (for Presta valves, loosen the small knurled tip and press it; for Schrader, just press the pin inside). Ensure all air hiss out so the tire beads aren’t stuck to the rim.

3. Unseat the Tire Bead: Lay the wheel on its side or hold it. Use your thumbs to push the tire sidewall inward, away from the rim edge, all around on both sides – this helps break the “seal” if it’s tight. Insert a Tire Lever: Start opposite the valve. Hook the rounded end of a tire lever under the tire’s bead (the edge of the tire) where it meets the rim. Pry that section of tire up and over the rim’s edge. Hook the other end of that lever onto a spoke to hold it if it has a hook. Now insert a second lever a few inches over and do the same, popping more of the tire off. You can then slide the second lever along the rim, prying the tire the rest of the way off one side of the rim. (Be careful not to pinch the inner tube with the lever as you slide​ – since the tube is deflated, it should be loose inside.)

4. Remove the Inner Tube: Once one side of the tire is off the rim, you can pull the tube out. Start at the valve: push the valve out through the rim hole and pull out the tube completely. If the tube is still partly inflated or stuck, don’t yank – make sure the tire bead is free everywhere and the tube will come out easily.

5. Find the Puncture Cause: This step is critical to avoid repeat flats. Inspect the outside and inside of the tire for thorns, glass, nails, or other debris that may have caused the flat​. Run your fingers (carefully) around the inside of the tire; you might feel a sharp object. Remove any offending object. Also check the rim strip (the band inside the rim covering spoke holes) to ensure no spoke holes or sharp edges are exposed that could puncture the tube.

6. Patch or Replace the Tube: If you have a spare tube, use that (it’s the quickest solution). If not, patch the hole: roughen the tube area around the puncture with sandpaper, apply a thin layer of rubber cement from your patch kit, let it become tacky, then press the patch on firmly. Wait a minute for it to set. (Many modern patch kits are glueless stick-on patches for quick application.) Using a New Tube: Slightly inflate the new tube just enough for it to hold a round shape – this helps prevent pinching. Locate the valve hole in the rim, insert the tube’s valve through it, and feed the tube into the tire all around.

7. Re-seat the Tire: Starting at the valve, tuck the tire bead back into the rim well, encasing the tube. Work your way around with your thumbs, pushing the tire bead inside the rim edge. As you get to the last section, it will be tight. Make sure the tube isn’t caught between the bead and rim – this is where many pinch-flats happen on reinstall. Push the final part of the bead over the rim edge. If it’s very tight, use your tire lever carefully: lever the last few inches of bead over, but ensure the lever isn’t catching the tube. Tip: Try not to use a lever if possible; using hands is safer for the tube. Often, pushing the tire bead down into the rim’s center channel opposite the tight spot gives extra slack to finish by hand​.

8. Inflate and Check: Add a bit of air and check all around the rim that the tire bead is seated evenly – you shouldn’t see any part of the tube sticking out. The tire should look uniform on both sides with no bulges. Inflate the tire fully (to your desired pressure, e.g. 60–100 psi for road, 30–50 psi for gravel, or as marked on the tire). As it inflates, periodically inspect that the bead is properly seated and not popping out anywhere. Once inflated, double-check again for any odd bulges or sections where the bead isn’t snapped into place (there’s usually a line on the tire sidewall that should be evenly spaced from the rim all around).

9. Re-install the Wheel: Put the wheel back on the bike. For the rear, guide the chain onto the smallest cog and line up the wheel; ensure the axle goes fully into the dropouts. Tighten the quick release (it should be firm to close, pointing upward or backward). If thru-axle, screw it in snugly. Re-engage the brake if you released it. Give the wheel a spin to ensure it’s straight and the brake isn’t rubbing. Finally, make sure the tire is at proper pressure and you’re good to go.

Common Mistakes: The number one mistake is not finding the cause of the flat. If you don’t remove that piece of glass or thorn from the tire, your new tube will puncture again immediately – always inspect the tire thoroughly. Pinching the tube under the tire bead during installation is another common error – this leads to a “pinch flat” (snakebite) the moment you inflate. To avoid this, take extra care in the last stages of seating the tire and inflate slowly, looking for any sign of the tube bulging out. Many people forget to slightly inflate the new tube before installing – an completely flat tube can easily get twisted or pinched. Also, watch the valve area: make sure the valve is straight and properly seated; sometimes the tube can get trapped at the valve causing a kink or tear when inflated. For rim brakes, a mistake is forgetting to reconnect your brake or adjust it if needed – always test your brakes after putting the wheel back on. Lastly, be mindful of directional tires (some tires have a rotation direction arrow); ensure you didn’t put the tire on backwards (though functionally it’s not the end of the world, it’s better to follow intended direction for tread and wear).

Quick Tips: Before hitting the road or trail, practice a flat repair at home in a calm environment. It greatly speeds up your roadside repairs when it actually happens. Carry at least two spare tubes on bikepacking tours or long rides – multiple flats can occur. A patch kit is light insurance if you run out of tubes. To locate tiny leaks in a tube, you can hold it near your cheek to feel air or submerge the tube in water (look for bubbles) if available. When installing the tire, some people apply a little talc/baby powder to the tube; this can help the tube slip into place and reduces pinching. If you discover a large gash in the tire itself, you’ll need to “boot” it – you can use a folded dollar bill, an energy bar wrapper, or a special tire boot patch inside the tire to prevent the tube from poking out of the cut. This can get you home in a pinch. Always remember to keep your tires inflated to the proper pressure for your bike and weight – underinflation can lead to pinch flats, and overinflation can make for a harsh ride or blowouts. With a bit of preparedness, a flat tire becomes a quick 5-10 minute fix instead of a day-ruiner.