Basic Man skill – you should have learnt this many years ago. Very simple and have a bike in bits and a bit of grease on your hands gives a great man look.
Find the puncture. If the tyre is blown out, or has a large hole, it will have to be replaced. If you rode it through a patch of thorns, or have been riding it whiles punctured (not a good look) for some time it may have many holes and not worth mending, but if it is a single small puncture it should be straight forward to fix.
Turn the bike upsidedown so it is placed on the seat and handlebars. (Make sure the weight is not on the brake levers or the gear shifter. Use a block of wood to support if need be.
Spin the tyre slowly. Look for anything stuck in the tyre, such as a thorn, a shard of glass, or any other object.
Let the remaining air out of the tube. If you have tyre valve great, otherwise a matchstick or pen can be used to depress the shrader valve and release the air. The valve stem is the small round piece of metal underneath the plastic cap where air is put into the tyre.
Pry the tyre off the rim. You should have a set of tyre levers with a decent puncture repair kit to help remove the tyre from the rim. Insert one between the rim and the tyre, push down on the lever to lift the tyre from the rim, insert the second tyre lever, and run it around the rim to remove the tyre. If you don’t have tyre levers a set of 3 spoons will work just as well: Push the end between the tyre bead and the rim, and pry the edge of the tyre off the rim. You will need to pry the tyre loose around the rim, about an inch or two (2.5 cm – 5 cm) apart, until the tyre becomes loose enough to pull free on one side.
Remove the innertube from the tyre. Remove the tyre being careful not to rip or damage the valve stem. The innertube should be hanging between the rim and the frame, so if it is a back wheel, don’t let it become entangled with the gears or chain.
Pump enough air into the innertube to inflate it sufficiently to find the leak. A bike tube will double or triple its original diameter, and the more air, the more the leaking hole will expand, making it easier to find it.
Look around the tube for the hole. Feel and listen for air escaping, you should be able to hear the hiss of the air escaping as you apply pressure to the innertube. If it is still difficult to find the hole, hold part of the tube under water, for example in a bucket, to see bubbles escaping from the hole.
Mark the location of the hole when you find the hole. Let the air out of the innertube once more.
Scratch up the area where you will install your patch. Most patch kits come with a small metal rasp to do this.
Spread a thin layer of glue around the puncture site. Allow it to dry until the liquid gloss disappears (or follow the instructions on the puncture repair kit). If you do not have any patches or patch glue, it is possible to use normal super glue without a patch. Let as much air as possible out of the tube. Spread a thin layer of glue around the puncture site. Again allow the glue to dry until the liquid gloss disappears. If using super glue it is best to leave it stand overnight.
Peel the plastic backing from the patch. Being careful not to touch the surface of the adhesive, place the sticky side of the patch on the tube, pressing it firmly into place. You will need to use one hand to hold the back of the tube and with the other apply enough pressure to get the patch to seal.
Now, a few moments after the patch has been applied, the tyre should be ready to re inflate and ride on.