Bicycle Repair Fixing a flat

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How to fix a puncture on a bicycle tire

What tools are needed?

A puncture repair kit containing:

You might also need:

Note: Pre-glued patches are recently available in all good bike shops. They are preferable in case of rain or other dampness because it is not necessary to wait for glue to dry. However, some sources claim that they are much less reliable than cemented patches.

How to do it

Step 1 (the easy way). Leave the wheel on the frame. Put the bike upside down or on some sort of stand. Go to Step 2 below, except do not completely remove the tube from the wheel. Most of the tube will come out and the patching can be done while the remainder stays in. If the hole is unfixable and the tube needs to be replaced, or if the hole is so small that it requires putting the tube underwater to search for bubbles, then go to Step 1 (traditional). Working around the wheel parts can be annoying, but it is often easier than wrestling off a wheel and fussing with brakes and gears.

Step 1 (traditional). Remove the wheel from the frame. On some bikes you need to detach the brakes to do this. If your bike has Quick release wheels (skewers), the wheel can be removed by loosening and unscrewing the quick-release bolts. If you wheel is attached to the frame by ordinary nuts they will have to be undone with a spanner.

If you have to take off the back wheel it is usually a bit more complicated, because you need to get the wheel past the chain. If your bike has multiple gears Derailleur gears, change into the very top gear to make it easier to get the wheel off past the chain. It is best to put the bike upside down when removing wheels, although it is possible to do it with the bike upright.

Step 2. When you have got the wheel off you need to lever open a gap in the outer tyre and remove the innertube. This is usually quite tricky because it means you have to squeeze the tyre out past the wheel rim, and this needs the tyre levers. If the tire is not fully deflated by now, open the valve and make sure it is, as any residual air will make it difficult to get the tire off and the tube out.

First, push the outer tyre as far in towards the wheel as possible. Do this by squeezing the edges of the tyre inwards and forwards and continue to do this right around the tyre. This is necessary because it reduces the diameter of the tyre and makes it easier to remove.

Then insert a tyre lever between the wheel rim and the tyre, and lever the edge of the tyre up over the rim. The tyre lever usually has a little hook at its non-levering end; use this to hook to a spoke and hold the tyre in place.

Now get another tyre lever and a bit further up the tyre, lever another bit of tyre past the rim. This can sometimes be quite difficult and often requires a lot of force.

After you have a fairly large section of tyre up over the rim, get a third tyre lever and start to lever the rest of the tyre over the rim, working your way around until the whole of one side of the tyre is over the rim.

Now you will be able to remove the innertube: carefully push the tyre valve through the hole in the wheel where it sits and with your fingers (do not use anything sharp) gently ease the innertube out from between the wheel and the outer tyre,

Step 3. Now that you have the innertube out you need to locate the puncture. The usual method of doing this is to pump up the innertube and put your ear to it: if you hear a hissing noise locate it and then use the crayon supplied with your puncture repair kit to mark the location of the puncture. If this dosn't work get a bowl of water and pump up the inner tube. Put it under water and then watch for bubbles, which indicate a puncture.

Step 4. After you have located the puncture, you need to patch it. To do this, first scratch the tube -lightly- with the sandpaper around the hole to give the glue a place to grip. Then apply a film (not too thick) of rubber vulcanising solution, supplied with your puncture repair kit, several centimetres around the puncture.

Wait for several minutes until the solution becomes dry and tacky. Now get a patch, peel off the plastic coating on its back, and stick it squarely over the puncture. Hold it down and press it firmly for a minute or so until it is firmly stuck. It is usually a good idea to pump up the inner tube to check that it has stuck properly and seals the puncture. Patches often have a clear fragile plastic layer on their top sides. This can be peeled off or left there indefinitely.

If you have a talcum block you should make some powder by rubbing it on the sandpaper, preferably a separate piece kept for this purpose. Rub the powder over the patch and the glued area to prevent either sticking to the inside of the tyre when pumped up.

Step 5. Now you need to get the innertube back into the outer tyre and refit the outer tyre. Before you do this, feel with your fingers the inside edge of the outer tyre to make sure that no sharp objects are still pointing through.

Now carefully with your fingers ease the innertube back into the gap between the wheel rim and the outer tyre, making sure that it is the right way around and isn't twisted. It is helpful if the tube has a very small pressure in it at this point to help it maintain its shape but still remain flexible; particularly if it is a new tube which is shipped with no air at all. You have to get the tyre valve back into the hole in the wheel where it sits, as well. Make sure the valve is correctly located and fully seated, as if it is tilted or offset the tube will bulge into the hole and spring another leak when inflated, which will be unfixable because of its location.

Now you need to lever the outer tyre back over the wheel rim with the tyre levers, which is usually easier than getting it off. You usually just need to gradually lever the tyre edge over the rim until the whole tyre is over it. While you are doing this try to make sure you don't get the innertube caught between the outer tyre and the rim.

You then need to reattach the wheel to the frame and make sure it is firmly attached, and pump the wheel up.

Notes

Keep in mind the following:

 

 

 

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