Replace an inner tube or a tyre

For the rear wheel, first shift the chain onto the smallest cog: the wheel will come out far more easily. With rim brakes, open the caliper's quick-release lever or unhook the V-brake noodle, otherwise the tyre will not pass between the blocks.

Open the quick release, or unscrew the thru-axle, and take the wheel out. At the back, pull the derailleur rearwards to free the cassette from the chain. With disc brakes, do not touch the brake lever while the wheel is out: the pistons would close up and stop the rotor from going back in.

Let out any remaining air. On a thin Presta valve, unscrew the small nut at the tip and press it. On a Schrader valve, like a car's, press the central pin. Also undo the nut that holds the valve against the rim, if there is one.

Then pinch the tyre all the way round the wheel, on both sides, to free its edges, the beads, from the rim and push them into the well in the middle of the rim. This makes the whole removal easier: the beads then have enough slack to pass over the rim edge.

Opposite the valve, slide the rounded end of a Tyre levers under the bead, lever the tyre over the edge of the rim, and hook the lever onto a spoke. Slide the second one in about ten centimetres further along, lever it over, then run it along the rim: one side of the tyre comes off completely.

Pull the inner tube out of the tyre, finishing with the valve, which you push out through the rim. To replace the tyre itself, pull the second side off by hand in one movement. Never use a screwdriver: it damages the rim and punctures the new tube.

A new tube will puncture again if the cause is still in the tyre. Pump a little air into the old tube and find the leak by ear, or in a bowl of water. Hold it against the tyre with the valve at the valve hole: the position of the hole tells you where to look.

Slowly run a rag, then your fingertips, around the inside of the tyre: a shard of glass, a thorn or a wire strand will catch. Remove it. Two small holes side by side mean a pinch flat, from riding with too little pressure. Finally, check that the rim tape covers every spoke hole.

Pump just enough air into the tube to make it round. If the tyre came off completely, first fit one side back onto the rim, following the rotation arrow on the sidewall. Push the valve through its hole, then tuck the tube into the tyre all the way round, with no twists.

Refit the second side by hand starting at the valve, a little at a time, working both ways at once. The end is hard: push the beads already fitted into the central well of the rim to gain slack, then roll the last section on with your palms. Avoid tyre levers here: they pinch the tube.

Pump up to about 1 bar, then look at the thin moulded line just above the rim, on both sides: it should sit at the same height all the way round. If it dips somewhere, let the air out, massage the tyre there and pump up again. Push the valve in, then pull it back out straight.

Then pump up to your pressure, between the minimum and maximum printed on the sidewall, and screw the Presta valve nut back down. Refit the wheel, tighten the axle, then close the rim brake's quick-release lever. Spin the wheel and squeeze each brake before you ride.