To repair a puncture you first need to remove the wheel from the bike so you need to release the brakes. V-brakes are released by pressing the top of the two brake arms together and disengaging the cable, allowing the arms to spring apart. Side-pull brakes often have switches that release the brake blocks from the wheel, or you may have to remove one of the brake blocks with an Allen key. If you have quick-release skewers, you simply open the quick-release lever and take the wheel off. If you don’t have quick release wheels you will need the right sized spanner (normally 15mm) to loosen the axle nuts, but otherwise the process is the same. If you are removing the rear wheel, make sure the chain is on the smallest outside cog (in top gear), making it easier to disengage from the chain.
Check to see if you can see where the tyre has been damaged. If it is obvious remember where the puncture is.
Using two tyre levers (1), carefully pull the tyre from the rim with one then 10-15 cm further along insert the next lever and pull that section off too. It will then be a simple case of pulling the bead off in either direction taking care not to rip the tyre or the delicate inner tube.
Take off the threaded collar nut and push the valve through then remove the inner tube.
Check the tyre (2) to see if the puncture was caused by a sharp object and if you find one remove it. There are two types of punctures, one caused by a sharp object and the other ‘pinch’ puncture caused by hitting a bump such as a kerbstone. If you keep your tyres inflated at the right pressure you can avoid these latter types of puncture.
Once you have found the hole (3) in the inner tube (you may need to submerge a semi-inflated tube to see where the air is escaping) rub down the area around the hole with sandpaper or a file (4).
Put a dab of rubber solution (5) on the hole, and gently spread it in a small circular area around the hole. Wait for the solution to dry, then apply the patch (6) ensuring that there are no air bubbles. When the patch is secure (7), grate some chalk on the area to prevent the inner tube sticking to the tyre when it is replaced.
Before replacing the tube check both the inside and outside of the tyre ensuring that all sharp objects have been removed.
Put the tube back inside the tyre which should still be hooked onto one side of the rim, then push the other side of the tyre on (8). Do this so the last section is at the valve making it easier for the tyre to grip into the hooks on the inside of the rim. Go as far as you can with your hands then simply push the tyre back on using your tyre lever (9).
Inflate the tyre (10) to around 20 PSI (1.4 Bar), check the tyre is seated correctly to ensure the inner tube isn’t pinched. Once you are happy, pump it all the way up to the manufacture specified pressure (11) and re-attach the nut and dust cap.