Any bicyclist at some point in their travels will get a flat tire. While certainly a nuisance, the flat bicycle tire does not have to be the end of your ride or the major frustration of your day. Fixing a flat bicycle tire can be very easy if done properly and with the correct tools.
Before you do anything, however, you will need to purchase some plastic tire levers from your local bike shop. These levers will allow you to pry the tire away from the rim because it is actually your bicycle tube that is flat, not the tire. Do not use a screwdriver for this repair! A screwdriver can put a nick in your rim that will cause future flats, or it may tear the tire and tube as you install them.
Once you have purchased your tire levers, put them aside and determine how to remove your wheel from your bicycle. There are two common ways a wheel gets fastened to your bike: either by two bolts — usually requiring a fifteen millimeter wrench — or by a "quick-release" lever, which simply requires you to flip the lever down and turn until the wheel loosens. Determine which system your bike uses and remove the wheel from the frame.
After you have removed your wheel from the bicycle, it is time to change the flat bicycle tire by removing the old, punctured bicycle tube. This is where your tire levers come into play. Tire levers typically come in sets of two or three and look similar to plastic screwdriver blades. One end of the lever is curved somewhat like a spoon, and the other end has a hook on it. Take the first lever and work the spoon end in between the bead of the tire — the hard part of your tire that sits closest to the rim — and the rim itself. Then push down on the lever. This will pull the bead of the tire away from the rim.
At this point, try to pull the lever in either direction around the rim to separate the tire from the rim. Some tires will come off easily, but others may be stubborn. If your tire is a stubborn one, pry that first lever back and use the hook end of the lever to hook it to the spokes. Then, take another tire lever and repeat the process about five to six inches away from the first lever. This should pull the tire away from the rim.
Once you have one side of your tire pulled away from the rim, note the position of the tube inside the tire. This will help you identify what caused the flat bicycle tire — if it is a puncture caused by a foreign object, keeping track of the tube’s placement will help you find the object and allow you to pull it out of the tire if it is lodged inside. Pull out the tube. Run your hand gently around the inside of the tire to clear any obvious debris. Be careful of any sharp objects that may be inside!
Once you have located the source of the flat bicycle tire, remove it, if it is an object, and get your new tube out. Inflate the new tube just enough that it takes shape, two to four pumps with a bicycle pump, and put the tube inside the tire by placing the tube’s stem through the hole in the rim first, then working the rest of the tube around the rim. Once the tube is inside the tire, use your fingers to reset the bead of the tire inside the rim. For tougher tires, use the tire lever to work the bead but be careful not to pinch the tube with the lever as this may cause another flat bicycle tire.
Once the tire is re-seated, inflate the tube to the recommended pressure written on the sidewall of the tire and replace the wheel in the frame. You have now finished changing your flat bicycle tire.