How to Fix a Flat Tire on a Bicycle

Bike shops charge up to $20 to repair a flat bike tire. You can save yourself some dough (and the hassle of finding a bike shop) if you happen to get a flat while riding by learning how to easily change a flat tire yourself. Read on to learn more.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• An adjustable wrench
• A bike stand, if available
• Tire levers
• 1 new inner tube
• A pump
• A clear space
• Soap

How to Fix a Flat Tire on a Bicycle

1. Buy a set of tire levers (there are typically three in a set) from a bike shop—these cost less than $5. This will save wear and tear on your muscles and hands, since most tires are designed to fit tightly on the wheel and therefore difficult to pry loose.

2. Get a tube that matches your tire size. The tire size is represented by a diameter and tread width (in inches or millimeters). For example, most mountain bike tires are 26-inch diameter and between 1.5 and 2.5 inches in width. The tire size can be found on the sidewall of the tire, just like on a car. Tubes are chosen first, based on the diameter, and can usually fit a range of tread widths. For example, a tire that is 26-by-2 can usually accept a tube that is 26-by-1.75 or 26-by-2.25, in addition to the exact size printed. Tubes come in a variety of qualities, from the very basic to extra-thick, or "thornproof." Usually just the basic tube (around $3 to $5) will do the trick.

3. Remove the entire wheel from the bike. To do this, put the bike on a stand, if one is available. If not, simply turn the bike upside down so that it's resting on the seat and handlebars. Make sure it's stable. Many wheel have a "quick-release" mechanism that require no tools to remove. You can tell if this is the case by looking for a tab-like metal piece on one side of the axle. Flip the tab loose, holding the other side (shaped like a cone), and unscrew slightly. The wheel can then be removed from the bike. If the bike does not have a quick-release mechanism, you will need to loosen the nuts on both sides of the axle with an adjustable wrench. Loosen almost all the way (or completely if needed) and remove the wheel, being careful not to lose the nuts.

4. Once the wheel is off, make sure the tube is completely deflated. If the tube has a valve cap, remove it. Take one tire lever and pry underneath the edge of the tire, lifting it over the lip of the wheel. Now take another tire lever, and moving farther along the tire, pry again. At this point, enough of the tire should be over the lip of the wheel so that you can use your hands to go the rest of the way. When done, one side of the tire should still be between the two lips of the wheel.

5. Push the valve stem of the tube up through the hole, holding the edge of the tire back so that it clears. Then remove the entire tube.

6. If it's not obvious where the tube is leaking, use the pump to inflate the tube and listen for the leak. Match the area leaking with the tire and check outside and inside the tire (by running your finger inside) to see if the object that caused the leak is still present.

7. Tubes sometimes develop slow leaks over time, which may not be detectable. For these cases, you can fill a pail with water, inflate the tube, and slowly rotate it through the water until you see bubbles coming from one area.

8. Take out the new tube and inflate it slightly, just enough to give it a little shape. Using the opposite approach to removing the tube, first push the valve stem through the hole in the wheel. Then slowly work your way around the tire, pushing the tube gently into the tire cavity.

9. Using your hands, start guiding the tire back onto the wheel. Start near the valve stem to make sure it is seated in the wheel. When it gets too difficult to use your hands, use the tire levers. Be careful not to pinch the tube between the tire and the wheel.

10. Use the pump to inflate the tube a bit more. Using your hands, wiggle the tire back and forth, working your way around the circumference of the wheel. This motion will help "seat" the tire and the tube, to avoid pinching the tube.

11. Inflate the tire to the desired air pressure. Like the tire size, the appropriate pressure is noted on the sidewall of the tire. If your pump doesn't have a built-in pressure gauge, use a basic one. If you have no gauge at all, you can guess at the right pressure. When properly inflated, it should be difficult to squeeze the tire very much.

12. Put the wheel back onto the bike, using the reverse of Step 3. If replacing the rear wheel, make sure the chain is properly on the gear cog(s). Secure the wheel and spin the pedals a few times to ensure that everything is lined up.

13. Take the bike off the stand (or turn it over). Then, go wash those hands!

Tips & Warnings

• If the flat is on the rear wheel, shift the gears before taking the wheel off so that the chain is on the bottom-most (smallest) gear ring in the back. This will make it easier to put the tire back on when done.
• Be sure to check the tires themselves—bikes that have been sitting in storage for a long time can develop cracks on the tires. If the sidewalls of the tires are cracked, the tires themselves should also be replaced.