How to Change a Flat Tire

01
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Fix a Flat Tire

Remove the wheel from your bike.
Remove the wheel from your bike. (c) David Fiedler, licensed to About.com

The first and most basic bike repair you need to know is how to fix a flat tire. It's quite simple and all you'll need are tire tools, a replacement tube and a pump.

Tire tools are cheap and light. They're about the size and shape of ​a toothbrush handle, and it's a good idea to carry a couple with you whenever you ride. They're easy to fit in a small pouch under your seat along with a spare tube, and with a frame-mounted pump, you're all set.

The first step is to take the wheel with the flat off your bike. Do this by loosening the nuts on the axle or by opening quick release mechanism that holds the wheel until it slides out of the slots on the front fork. You may need to loosen your brakes to get the wheel off. These often have a quick release mechanism too. If you are removing a rear wheel, it will have to be lifted clear of the chain.

02
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Remove the Tire from the Rim

Tire tool removing a bike tire.
Use a tire tool to remove the tire from your rim by wedging the tool underneath the tire and then lifting upward. (c) David Fiedler, licensed to About.com

Using tire levers, remove the tire by wedging the tire tool between the tire and rim, and then prying upward to lift the tire away from the rim.

Keeping the first tool in place under the tire, repeat this step about four inches away with the second tool to pull more of the tire over and off the rim. Repeat this step as you work your way around the rim. The one edge of the tire you’ve been working on should start to come free of the rim quite easily. You can finish this step by simply sliding the lever underneath the tire the rest of the way around the rim.

03
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Separate the Valve Stem from the Rim and Pull Out the Tube

Remove the valve stem from the rim.
Remove the valve stem from the rim. (c) David Fiedler, licensed to About.com

Next, you'll need to remove the valve stem from the rim. This is the metal valve that pokes through the rim used to inflate the tube. Locate the valve stem and push it up and through the hole in the rim so that it no longer protrudes through the rim.

Remove the tire and tube the rest of the way. You can usually do this easily by hand, but if you have trouble getting the edge of the tire completely over and off the rim you can use the tire levers again. Once the tire is off, pull the old tube out of the tire. You can then either discard the old tube, recycle the tube or attempt to patch it.

If your tire is flat because of a puncture, after you remove the old tube check the inside of the tire thoroughly to make sure whatever caused the flat is not still lodged in the tire (Here are a few easy ways to avoid more flat tires in the future.).

04
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Insert the New Tube into the Tire

Replace the tire on the rim.
Replace the tire on the rim, using tire tools when necessary. (c) David Fiedler, licensed to About.com

Take the new tube and work it into the tire, inserting it in preparation for remounting on the rim. Take care that the tube is not crimped or twisted at any point. Some people find that the tube is easier to work with if you put just a little bit of air in it, enough to hold it in the tire.

Put the tire and new tube back on the rim by first lining up the valve stem with the hole that it will need to go through on the rim. This is the reverse of what you did when removing the old tube in the previous step. Start by working the first edge of the tire back onto the rim where the valve comes out of the tube. As you seat the first edge of the tire onto the rim, use your fingers to carefully guide the valve stem back into its hole. Finish putting the first edge of the tire completely on the rim.

When you reinsert the valve stem of the new tube into the rim, be sure that it comes straight out of the hole and not be angled in any direction. Any tilt in the valve stem tells you that the tube is not centered over the hole. You can correct this by sliding the tube and tire around the rim just a bit in the proper direction to correct the tilt.

05
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Seat the Tire Snugly on Rim

Tire mounted on rim.
Here's the way the tire should look properly seated on the rim. (c) David Fiedler, licensed to About.com

Use your hands to work as much of the second edge of the tire onto the rim as you can. It will become more difficult as you go and you will most likely need to use the tire levers to put the last part of the tire onto the rim. Do this by wedging the tire tools against the rim below the edge of the tire that still needs to go on, and then working one lever and then another to bring the edge over the rim until the whole tire is seated snugly and comfortably once again inside the rim.

Once the new tube and tire are back on the rim, do a quick check with your eyes and fingers around both sides of the rim to make sure that the complete edge of the tire is inside the rim, and that at no point is the inner tube pinched between the tire and rim or protruding over the rim.

06
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Inflate The Tube

Inflate the tire.
Inflate the tire to proper pressure shown on side of tire. (c) David Fiedler, licensed to About.com

Using the pump, inflate the tire to the pressure recommended on the sidewall. Another option, particularly if you are out on the road (or out in the woods on your mountain bike) is to use a CO2 inflator with cartridges.  This is a slightly more advanced procedure.

As you put air into the new tube, make sure the tire is filling consistently. Any uneven inflation that you notice, such as a bubble or highly inflated portion of the tire while another part remains flat, tells you that your tube is pinched or twisted inside the tire and needs to be reset. Correct this by letting the air out of the tube and repeating Step Two, which allows you to look for the spot that is pinched or twisted. Many times you can fix this without removing the tire completely again. After fixing the twisted part, replace the tire and try inflating the tube again.

07
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Put the Wheel Back On Your Bike and then Go Ride!

Replace the wheel on the bike.
Replace the wheel on the bike. (c) David Fiedler, licensed to About.com

Put the wheel back on your bicycle, reattaching the nuts or quick release mechanism and resetting the brakes and replacing the chain as necessary. Check to make sure that the wheel is aligned properly, that it is held securely and that it spins cleanly. It should not rub against your brakes or your fork.

If you're clear of all these problems, now it's time to go off and ride your bike. A good final step is to do the quick five-point safety check to ensure your bike is is good working order right before you get on.