Fix a flat tyre, step by step

Every cyclist gets a puncture sooner or later. It is one of the most common bicycle problems, and one of the easiest to fix. Learning to do it yourself saves time, money and stress, and gives you the confidence to ride further. Practise once at home, in daylight, before you ever need to do it by the roadside.

What you need

• Two or three tyre levers.
• A spare inner tube of the right size, or a patch kit. Glueless patches are the quickest for roadside repairs; patches with rubber cement are more permanent.
• A pump that fits your valve type.
• A spanner, if your wheel has nuts instead of a quick-release lever.
• A small cloth or gloves, and a light.

The size of the tyre is printed on its sidewall, for example 26 x 1.95 or 700 x 28C. Buy a tube that matches it, and check whether your valve is the thin “Presta” type or the wider “Schrader” type.

Step by step: replacing the tube

1. Move to a safe spot away from traffic. Turn the bicycle upside down on its saddle and handlebar, or lean it against a wall.
2. If you have rim brakes, open the brake quick-release so the wheel can pass. Release the wheel’s quick-release lever, or loosen the nuts with the spanner. For a back wheel, shift the chain onto the smallest cog first. Remove the wheel.
3. Let any remaining air out of the tube by pressing the valve.
4. Hook the rounded end of one tyre lever under the edge (the bead) of the tyre and pry it over the rim. Hook the lever onto a spoke to hold it in place.
5. Insert the second lever a few centimetres along, and push it around the rim until one side of the tyre is completely off. You rarely need to remove the whole tyre.
6. Pull the tube out. Start opposite the valve, and finally take out the valve from the rim hole.
7. Find the cause. Carefully run your fingers along the inside of the tyre and the rim, feeling for thorns, glass or sharp wire. Remove anything you find. Check that the rim tape covering the spoke holes is in place.
8. Put a little air into the new tube so it holds its shape. Insert the valve into the rim hole first, then tuck the tube into the tyre all around.
9. Push the tyre bead back onto the rim with your hands, starting at the valve and working both ways. Make sure the tube is not pinched between the tyre and the rim, because that causes a new puncture.
10. Inflate to the pressure printed on the sidewall of the tyre. Check that the tyre sits evenly on the rim.
11. Put the wheel back, with the chain on the right cog for the back wheel. Tighten the quick-release or nuts firmly, close the brake release, and spin the wheel to check it runs straight. Test the brakes.

Repairing the tube with a patch

If you are patching rather than replacing the tube:

1. Inflate the tube a little and find the hole by listening and feeling, or by dipping it in water and watching for bubbles.
2. Roughen the area around the hole with the sandpaper from the kit and wipe it clean.
3. Spread a thin layer of rubber cement over an area bigger than the patch. Let it dry completely, until it is no longer shiny.
4. Peel the backing from the patch, press it on firmly and squeeze it for a minute, working from the middle outwards.
5. Leave it for a few minutes, then re-inflate and check there are no bubbles.

Avoid punctures in the first place

• Keep the tyres properly inflated. Low pressure causes “pinch flats”, where the tube is squashed against the rim.
• Look at your tyres during your ABC check and remove small stones or glass.
• Avoid riding through broken glass, and watch out for potholes and sharp edges.
• Replace tyres that are cracked or worn smooth.

Carry a small kit

A small bag under the saddle with a spare tube, two levers, a patch kit and a mini pump weighs almost nothing, and can turn a long walk home into a five-minute stop.