Every cyclist knows that from time to time, a bicycle tire will go flat and no amount of puncture repair can fix it. The only thing to be done is to remove the tire completely and replace or mend the inner tube.
Step 1 - Position the Bike
Place the bike upside down, so it is resting on the seat and handlebars. When removing the wheel, remember the brakes should be in the ‘off’ position, so they are not gripping the bicycle tire.
Step 2 - Remove the Wheels
Wheels can be removed either by using the quick release mechanism (available on newer bikes), or by loosening the nuts that hold the wheel on. If the nuts are very tight, try spraying some lubricant on them (using vegetable oil will suffice in a pinch). Once the wheel is loose, remove it from the bicycle frame. If it is a rear wheel, be sure to lift it over the chain. Rear wheels can be removed more easily by putting the chain on the smallest gear before loosening the wheel.
Step 3 - Remove the Tires
Lay the wheel out flat on the ground, and kneel or sit beside it. Press down on the inner valve in order to completely deflate the tube. This will make removing the bicycle tire much easier.
Step 4 - Use a Tire Lever
The quickest way to remove the tire from the wheel is by using a tire lever. This is a flat plastic tool that fits between the bicycle tire and the wheel frame. If you do not have one, the edge of a spoon or a spanner can be used, although you will need to be careful, as these can damage the rims or slice through the inner tube.
Slide the tire lever between the bicycle tire and the frame, or ‘rim’, and pry the tire upwards, levering the bicycle tire away from the rim. Keep the lever under the tire, and use a second one about five inches away; pull more off the rim, and then move the lever again. After two or three times, the bicycle tire should come away from the rim and the lever can be slid around the whole underside of the tire in order to release it from the rim.
Before completely removing the wheel from the rim, you will have to remove the valve stem, the metal tube that sticks through the rim and is used to inflate and deflate the tube. There is a small nut at the top of the valve which needs to be unscrewed before it can be removed; then it can be pushed through the rim so it is free of the wheel frame. It is important to release the valve this way, as dragging can seriously damage the valve.
Now tug the tire away from the rim (you may need more levers to release it if the rim has been dented), and lay the bicycle tire on the ground. Now the tube can be removed.
Step 5 - Attach the New Tube
There will be an arrow on the wheel indicating the direction in which a new tube should be rotated in order to fix it. Partially inflate the new tube and then slowly fix it on the wheel. Do this at one side first and then continue over the entire circumference of the wheel. When the tube is in place, inflate the tube using the valve provided on the wheel. The tire should expand evenly and not pinch over the wheel.