How to fix a flat bicycle tire:  
1. Before you ever leave home, take your spare and slightly inflate it. Then sprinkle with a little baby powder over the entire tube and run your hand over the tube to even out the powder. Let the remaining air out, pack it in a zip lock bag (to keep it dry) and put it in your pack. The powder will allow you to "shake" the tube up into the tire after it's installed and prevent a pinch flat!

2. To change a flat tire: Remove one side of the tire bead with the levers as shown in the diagrams starting opposite from the value.

3. Pull out the tube but leave the valve in place sticking through the rim. This way, when you locate the leak, you can figure out where the tire puncture is located. Check that part of the tire for embedded glass or rips.

4. Inflate the tire as best you can and look for the leak. Sometimes it's obvious, else hold the tube near your ear, listen along the tube and you may feel or hear the air escape (occasionally you will have to remove the tire completely and hold it up to your ear or cheek).*

5. Replace the tube. Fill the tube just very slightly and fit it into/around the rim.

6. Starting at the valve, push the tire bead onto the rim. Keeping the wheel flat, using both hands, one moving along the right and the other left, working away from the valve stem. Pushing on the last little bit is of tire is a "*##*@." It takes 2 hand and there are some tricks I'll add later. But take heart! "Crank Brothers " offers a small plastic tool, "Speed Lever," that has yet to let me down and is available online and at many bike stores and is excellent for flat tire repair. It comes with directions, is very light and easy to carry.

7. When the tube has been inserted and the tire is now on, inflate the tube just very slightly. "Shake" the tube all the way round checking that the tube is not caught between the tire and rim causing pinch flat. If you can't see the inside of the rim as you do this, let some of the air out and try again. Check both sides of the tire and rim. Also push the valve stem up & down to make sure its not pinched. See video and last picture on the left.

8. Now your ready to inflate your tire to the correct PSI (it's usually written right on the tube) and away you go.

*If you find a rip in your tire, there's a good chance you have a "boot" in your wallet/purse. Yes, just wrap a dollar bill around the tube where the tire rip is (hooray for Uncle Sam).


Tools: Spare tube, tire levers, pump (Optional but very helpful: baby powder, Crank Brother tire tool)
 
Time: 7 to 10 minutes (with practice)

Difficulty: 1-2

 
                     

A puncture caused by road debris will be found on the outer side of the tube opposite to the valve.


A "snake bite" puncture will show two rips, one on either side in relation to the valve. Such a punture can be caused by underfilling the tire (low psi), worn tire bead (the bead is the tire edge) on a tire with many miles, or just a result of a large pot hole that when hit at a good clip will compress the tire and allow the tube to get "pinched" at the point of impact.


Use 2 or 3 tire levers to free the tire bead from the rim.


Remove the tire.


Inflate the tube and check for a leak. Don't forget to run your fingers over the inside and outside of the tire to look for embedded debris.


Add a small amount of air to a new  tube and push it into the rim. Next push the tire bead on to the rim.


You can use your hands to re-intall the tire over the rim, or use the "Crank Brothers Speed Lever" as shown in the video.


After the tube has been inserted in the tire, inflate with just enough air to allow one to bend the tire and look inside. One should see the rim tape and not the tube. If you can't  bend the tire, let a little air out. If it's to easy to bend, add some air. Bend back and forth to shake the tube up into the tire, while checking that the tube is not "pinched" between the tire and rim. Move all the way around. Also push the valve up and down until it moves freely. Turn the wheel around and repeat on the other side. This takes a few minutes, but it's worth it.