How to change a bike inner tube, step by step

Changing an inner tube is a fifteen-minute job once you have done it a couple of times, and it is well worth learning before you actually need it at the side of a road.

The short version: let all the air out, take the wheel out of the frame, unseat one side of the tyre with levers, pull the old tube out, work out what caused the puncture, fit the new tube, push the bead back on by hand, then inflate in stages and check the bead is sitting evenly.

The step people skip is finding the cause. If the thorn, shard of glass or sharp spoke end is still in the tyre, the new tube will fail in exactly the same spot within a mile or two.

• Two or three plastic tyre levers
• A spare inner tube of the right size and valve type
• A pump — a track pump with a gauge at home, a mini pump or CO2 inflator on the road
• The right tool for your axles: quick-release levers need none, through-axles usually need a hex key, bolt-on hubs often a 15 mm spanner
• Something to wipe your hands, and a patch kit or tyre boot in case the tyre itself is damaged
• A bucket or bowl of water if you are working at home, for finding the hole in the old tube

Nearly every "new tube blew immediately" story is a tube trapped between the tyre bead and the rim, pinched as the last section goes over. A few habits prevent it:

• Keep the section of bead you have already fitted pushed into the deep centre of the rim. That slack is what lets the final few centimetres go over by hand.
• Push the valve up into the tyre slightly while you fit the second bead, so the tube cannot be caught under the bead at the valve.
• Roll the last bit over with the heel of your hand, working in short pushes rather than one big heave.
• If you genuinely cannot get it on by hand, use a lever gently — hook it under the tyre bead only, never under the tube — and then recheck the whole circumference for pinches before inflating.

• Bead line even all the way round on both sides
• No tube visible between tyre and rim, and the valve sitting straight
• Wheel fully seated in the dropouts, with the quick-release lever closed firmly (it should leave a mark in your palm, not spin freely)
• Brake quick-release closed
• Wheel spun to check for rubbing and to confirm it runs true
• Brake lever squeezed hard while stationary
• Tyre at the pressure you normally run

• Never exceed the maximum pressure on the sidewall. If the tyre will not seat, stop pumping and find out why — more air is not the answer.
• Metal tyre levers can scratch rims and pinch tubes; plastic is the safer default, and especially so on carbon rims.
• CO2 inflators discharge freezing cold. Hold the cartridge with a glove or a cloth, and inflate with a proper pump once you are home, as CO2 leaks out of butyl tubes faster than air.
• A cut sidewall is not a puncture. Fit a tyre boot between tube and tyre to get home, keep the pressure low and replace the tyre rather than riding on it long term.

A single clean puncture in the main body of the tube is a good candidate for a patch, provided you roughen the area, apply the solution, let it go tacky and press the patch on firmly. A patched tube is fine to ride.

Replace rather than repair when the hole sits right at the valve, the valve itself is torn, the tube has several holes in a cluster (a sign of pinch flats from low pressure), or it has already been patched repeatedly near the same spot. A patched tube also makes a sensible spare to carry, so the good tube stays on the bike.

• Check pressures weekly. Soft tyres are the main cause of pinch flats, where the tube is nipped against the rim.
• Wipe the tyres down after wet rides and pick out flints and glass while they are still on the surface.
• Replace rim tape when it looks thin, split or has been pushed off-centre by a spoke.
• Ride a little further out from the gutter, where debris collects after rain.
• Retire a tyre once the tread is squared off or the casing is cut — most stubborn repeated punctures trace back to a worn tyre.