It's a given fact that sooner or later you will have a flat tire. You'll be cycling along when all of a sudden you hear hissing or a sudden pop and one end of the bicycle will start to sink. I've had it happen to me many times. During one day back in December, 1998, I had eight flats because I had my tubes punctured by mesquite thorns along the interstate in Western Texas.

Here's a step-by-step guide to help you fix flats. You will not need these instructions after you have done these procedures a couple of times. If you are working at home and have access to a repair stand use it. On the road, it is not really necessary to support the bike but you might one to think about hooking the saddle over a fence or a low branch if it possible. Or if you are riding with somebody, you could ask your partner to hold up the bicycle for me. I had luch in just tipping the bike over on it's side and let the panniers take the weight. The tools that you need to carry with you are a frame-fitted pump, pocketknife, rag, spare tube that is fitted to your tires, and tire irons.

Step One - Open the brake

To make it easy for you to remove and put the wheel back on, the brakes need to be widened. For a cantilever brake, both brake pads need to be squeezed against the rim with one hand and you need to unhook the transverse cable from the brake arm. This is easy when you have quick-release brakes. With sidepull brakes, you need to look for a lever on the caliper or lever handle and open it to spread apart the brake pads.

Step Two - Remove the wheel

Most of the newer style bikes have quick-release (qr) hubs so that the wheels can be removed without tools. If the flat tire is the rear one, you need to shift into the smallest cog to move the derailleur to the side. To remove either one of the wheels, you need to open the qr by flipping the lever one hundred eighty degrees. You should feel the the qr open and you might see the word "open" on the lever. It would be a help if you pull the derailleur back with one hand as you push the window forward and down with the other hand.

Front wheels will probably not come off easy when the qr is opened. Many bicycles have nubs on the fork dropouts that capture the quick-release so that the front wheel will not dislodge if the lever is improperly tightened. If this is your set-up, you need to hold either end of the quick-release and unscrew the other end until the quick-release clears the hubs.

Step Three - Remove the tire

If there is any air left in the tube, you need to deflate the tube completely. With a schrader valve you can depress the valve stem with a corner of a tire iron. With a presta valve, you need to unscrew and depress the top of the valve. After this is done, you need to hold the wheel upright and slide a tire iron under one side of the bead at least one hundred eighty degrees from the valve stem. Pull the tire iron downward to pry the bead off the rim and then either hold it or hook the tire iron to a spoke.

Place the second tire iron under the same bead about four inches from the first tire iron and pull it downward. Repeat this procedure leapfrogging the levers. Soon you will be able to slide the tire iron around the rim to free that entire side of the tire.

You can then reach inside the tire and extract the tube except where the valve stem goes through the rim. Go one hundred eighty degrees from the valve and pull the tire up and off the rim. Use tire irons if the tire is tight. A presta valve might be held through the rim by either a nut or a knurled ring that nust be unscrewed before the tube can be completely removed.

Step Four - Replace the tube

The easist way to fix a flat tire is to just replace the tube. You can save the punctured t ube to patch it at home. Before installing the new tube, you need to make sure that the tire doesn't have anything sticking through it that could puncture the new tube. A good way to check this out is to wad up a rag and slowly slide it inside the tire in both directions. If the rag catches onto something sharp, you should be able to pick it out with the pocketknife.

Inflate the new tube just enough to remove any wrinkles. Feed it into the tire. For a professional lookk, you can align the valve stem with the tire label.

Step Five - Installing the tire

Lay the wheel on its side and place the tire/tube combo on top with the valve stem at the valve hole. Start installing the tire by putting the valve stem partially through the hole and working the lower bead of the tire onto the rim all the way around. If the valve stem will not go through, the rim strip's hole is probably off center. To mount the second bead, you need to start at the stem and work the tire over the rim with both hands.

The last section of the tire will probably be tough to get on. It would help to fully deflate the tube, place the wheel on a knee, hold one of the uninstalled sections to keep it in place, and use the heel of your stronger hand to roll the bead up and over the rim. Use tire irons as a last resort because there is a good chance of danger of pinching a hole in the tube. After the tire is mounted, you need to push the valve stem into the tire to make sure that the tube isn't caught under the beads and then pull it out again.

Step Six - Inflating the tire

Place the pump onto the tube valve. Brace it by wrapping your thumb over the tire so that is will not bend or break the valve when you pump forcefully. Inflate the tube fully and then check it for proper seating. On most tires, there should be a fine line molded into the side of the sidewall , which is called a "bead line", that is equal distanced from the rim all the way around on both sides.

Spin the tire to eye this. If the line dives beneath or bows above the rim, you need to deflate the tube and wiggle the bad section. Add air and recheck. An incorrectly seated bead will prevent the tire from rolling smoothly. It could also let the tube squeeze through and blow out. Sometimes, you might have to carefully poke the tube under the bead of the tire with a tire iron.

Step Seven- Installing the Wheel

To install a front wheel, you need to stand the bicycle up and place the wheel in the fork with the quick-release lever on the left hand side. Make sure that the wheel's axle is fully inserted in the dropouts. If you had to unscrew the quick-release mechanism to bypass the dropout nubs, hold the lever open and turn the nut clockwise. This adjustment is done correctly when the quick-release begins to clamp after you have closed the lever about halfway. When the quick-release lever is fully closed, the lever should point upwards or to the rear next to the fork blade. The force needed should leave an impression on your palm.

The procedure to reinstall the rear wheel is very similiar. Clamping the quick-release should be easier as turning the lever. When installing the rear wheel, you need to put the chain onto the smallest cog and make sure that the wheel is centered between the chainstays and the seatstays. Finish the job by rehooking the cantilever brake cables or close the sidepull quick-release.