Fixing an inner tube is one of the most common bicycle repairs. Being able to fix an inner tube is a useful skill for anyone to have. This guide applies to all bicycles with inner tubes. It deals specifically with how to patch up a punctured inner tube. For a guide on how to replace an inner tube, see the following link. (See Replacing an inner tube)
Inner tubes have different valves. Your inner tubes may have one of the following:
The Dunlop valve (also Blitz or Wolf valve, Dutch valve, DU)
The Schrader valve (also auto valve, AV)
The Presta valve (also Sclaverand valve or French valve)
Each valve type works slightly differently. The Dunlop valve has a removable inner mechanism that is kept in place with a ring. To drain air from the inner tube, all you need to do is loosen this ring. The Schrader valve has a fixed inner mechanism. The pin inside can be pressed to let air out of the tube. The Presta valve has an inner mechanism with a small lock nut that can be loosened in order to release air.
Step 1 : Removing a tire
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Let any remaining air out of the inner tube through the valve and remove the bottom ring that keeps the valve in place.
Press the valve down as far as you can to create space to maneuver the bicycle tire.
There should now be enough space to work on the tire.
Insert one tire lever between the tire and the rim, opposite the valve hole, by pushing the tire aside. (1)
Make sure the tire lever is inserted deeply enough that you can use it to lever the tire bead over the edge of the rim flange.
Use the tire lever to lift the tire off of the rim and use a spoke to anchor the tire lever in place. (2)
Repeat this step about three spokes further along, using the second tire lever. (3)
Now that the tire is sufficiently separated from the rim, the first lever can be used to repeat the previous step a few spokes further along.
Once the tire is sufficiently “loosened”, you can manually remove the entire tire from the rim.
You should now be able to remove the inner tube from the tire manually.
The tire should be pushed aside a little by the valve, to create enough space to remove the valve from the rim.
Sometimes a puncture is so small that you can’t detect it by sight, hearing or touch. In those cases, using a tub of water or a leak detector can help.
Step 2 : Detecting the puncture/cause of a leak
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Once you’ve removed the inner tube from the tire completely, it’s time to find the leak.
Gently inflate the inner tube to create pressure. (1)
If the puncture is big enough, you will be able to hear and feel air escape through it.
Mark the puncture using a pen or marker and place the bicycle tire next to the inner tube, so the valve is next to the valve hole.
The puncture in the inner tube should now be right next to the one in the tire. (2)
Carefully feel along the inside of the tire while also checking the outside, until you’ve found the cause of the leak. (3)
Remove the cause of the puncture (a pebble, for example) from the tire and check the rest of the tire, just to be safe.
Failing rim tape can also cause a leak in your inner tube. If your rim tape is failing, the inner tube is no longer be protected from the sharp ends of the spokes. Should this be the case, replace the rim tape immediately.
Use talcum powder to make sure the solution doesn’t stick to the inside of the bicycle tire.
Step 3 : Fixing an inner tube
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Lightly sand the marked puncture with sanding paper and wipe it clean.
This removes any greasiness from the tire and helps the patch adhere to the inner tube better.
Apply a thin coat of solution to a slightly larger area than the patch will cover.
Let the solution dry for about 3 minutes, until it starts looking dull. (1)
Remove the foil from the patch and place it over the hole, with the hole in its center.
Firmly press the patch to the inner tube to get rid of any air bubbles under the patch. (2)
Let the patch dry for about 5 minutes.
Lightly inflate the tire to its original shape and check whether the patch remains in place on all sides. (3)
Step 4 : Putting an inner tube inside a tire
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Insert the valve back through the valve hole and screw the bottom ring back on until it’s about halfway down the valve stem, leaving enough space to push it further down into the tire. (1) Lightly inflate the inner tube, until the tire fold is almost invisible. (2)
Feed the inner tube into the bicycle tire completely and make sure that the tube fits evenly. (3)
Now you can start to put the tire bead back onto the rim.
Step 5 : Putting a bicycle tire on the rim
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Push the valve down into the tube as far you can to create space for the tire. (1)
Then put the tire bead back over the rim, starting opposite the valve hole.
Put the rest of the tire back on the rim and make sure that you end up at the valve for the last part of the tire. (2)
Make sure that the tire is pushed into the rim bed as far as possible, leaving enough space for the last part of the tire.
Let some air out of the inner tube, if necessary.
Try putting the last part of the tire on the rim by hand. (3)
Avoid using tire levers for this; chances are that you will end up puncturing the inner tube.
Gently inflate the tire to the right pressure and tighten the bottom lock nut until it is flush with the rim.
Make sure that the tire is evenly centered on the rim.
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Step 1 : Removing a tire
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