Punctures are just one of those things in life—they happen to everyone sooner or later. If you’re out for a ride, you need to be prepared for the worst by carrying a spare inner tube for your bike. However, if you haven’t got one along or someone in your group has different-sized tyres to you, you'll need to break out the puncture repair kit to fix the puncture and get going again.
If you’re cycling, keep your eyes peeled for broken bottles near the gutter, or for tell-tale leaves on the road where branches of bushes have been cut. If you’re cycling in the countryside where the hedgerows and ditches have been trimmed, try to steer clear of where the debris has fallen on the road, as it may contain thorns from whitethorn bushes or briars.
But if the worst does happen, you'll need the following to fix that puncture: a tyre lever, a bike wrench/universal tool, a bicycle pump (or a CO² cartridge), a new inner tube (if you’ve got one), or a standard puncture repair kit, which normally includes a selection of patches, a tube of vulcanising fluid, a square of sandpaper, and maybe a new valve. Oh, and just to make things easier, pop a toothpick into the kit as well…
Extracting the tube
The first step is to find a nice, clean paved area to fix your puncture: puncture repair under a tree sounds inviting, until you lose a valve in the grass. Also, keep away from storm drains—if your patches fall in there, you’re walking!
The next step is to take the punctured wheel off the bike—release the brake callipers (if necessary) and undo the quick release if it’s the front, or run the chain onto the smallest sprocket to take off the back wheel by pulling back the derailleur mechanism.
With a gentle pair of hands, insert the tyre-lever under the bead of the tyre on the side opposite the valve. Slide the tyre lever gently along the rim to pull the bead over the rim of the wheel—you need the tyre half-on and half-off the wheel to fix the puncture.
Pull the tube out with your fingers and, leaving the valve still stuck in the wheel, pump it up just enough so that it regains its shape. If you pump it hard enough, you should hear a whistling (and hopefully not a ‘whooshing’) sound that tells you where to look for the hole.
Finding the Puncture
If you’re really fortunate, you'll have something like a basin of water to dip sections of the tube into, with the escaping air bubbles helping you to find the puncture quickly. On the road, however, you’re unlikely to be so lucky. If your eyes aren’t the best, you can also find the puncture by passing your fingers over the tube and listening for that moment when your fingers block the hole and audibly alter the jet of air as it escapes. If the hole is really tiny (like for a very slow puncture), you can hold the tube close to your face to fell the tiny jet of escaping air (Tip: the skin around your eye is most sensitive).
Once you’ve found the hole, don’t lose it again—insert the toothpick (or a wooden matchstick) into the hole while you get the fluid and the patch ready, and loosen the valve to let the air out.
With some bicycles—and especially bikes that stand around a lot, or are handed down from one child to the next—a common problem can be that the rubber in both the tyre and tube perishes over time due to exposure to light and the environment. This can mean that the tyre and tube can develop weak spots, especially at points of extreme stress like around the valve. If you find that the tube has a crack or a cut around the rubber base of the valve, don’t bother trying to repair it—you'll definitely need a new tube. The same goes for long cuts or cracks in the tube—the tiny patches in your repair kit will never fix them.
Preparing the Ground
Prepare the area around the puncture by rubbing it with the sandpaper to provide a key for the vulcanising fluid, which sticks the patch to the tube. Lay down all the materials you'll need in one place, and sit down beside them. Remove the toothpick from the hole and roughen an area larger than the patch with the sandpaper, wrapping the tube around your knee to give yourself a surface to work on. Providing a key means that the vulcanising fluid can seep into the tiny scores you make in the rubber, forming a super-strong bond.
Next (and after reading the instructions on the tube of fluid carefully), apply a thin film of vulcanising fluid to the tube, and let it ‘go off’ or cure for at least one minute before applying the patch. If you don’t let the vulcanising fluid go off or you put on the patch too soon, the patch simply will not stick to the tube.
‘Vulcanisation’ is a bonding process for turning natural rubbers into more durable forms. The vulcanising fluid is a kind of miracle glue that bonds the patch so tightly to the tube that they effectively become one. A poorly applied patch, however, will pucker and peel off.
After applying the vulcanising fluid, replace the cap on the tube of fluid immediately to avoid it going off in the tube.
Applying the patch
Most patches come with a silver foil stuck to the sticky side and a clear cellophane foil on the back. After the vulcanising fluid has gone off, carefully peel back the silver foil, gently peeling the foil directly back over itself to avoid removing the cellophane foil. Never touch the sticky surface of the patch—the greases and oils on your skin would weaken the bond. Only pick up and hold the patch by the cellophane foil.
Round the puncture over your knee, and carefully apply the patch to the puncture with a rolling motion—the hole should be in the dead centre of the patch.
Starting at the centre, rub the patch into the tube from the centre of the patch to the outside, as hard as your fingers (and your knee) can take it. Pay special attention to the edges of the patch: ensure a large enough area is roughened, that it is coated with an even film of vulcanising fluid, and that the extreme edges of the patch are very firmly rubbed onto the tube.
Once the patch has been firmly rubbed onto the tube, you can carefully peel off the cellophane backing. Be careful not to pull the patch back off the tube, however, and if in doubt, just leave the cellophane on the patch.
Check the Tyre
Match the location of the puncture on the tube with the position on the tyre, and slowly run your fingers over the inside of the tyre to check for thorns. Move slowly and softly to avoid cutting your fingers, and when you find the cause of the puncture, push it back out with the heel of your tyre lever. Remove it from the surface of the tyre like you would a thorn from your finger. Check the tyre for other foreign bodies before lightly pumping and replacing the tube. Pumping the tube a little ensures it will sit right and not get pinched when you replace the tyre. Now, using your thumbs or the heel of your hand, push the bead of the tyre back over the rim of the wheel.
Once tube and tyre are in their correct positions, pump it as hard as you can before putting the wheel back on the bike. Gather up all fragments (and any rubbish, especially the silver foil from the patch) and hit the road again!
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