How to fix a puncture on the road: tools to carry, tubes, tubeless plugs and CO2 vs pump

TUREFF• •0

Every cyclist gets punctures, and the difference between a five-minute stop and a long walk home is what you carry and whether you have practised. Fix one at home first, in the warm, and the roadside version will be much less stressful.

What to carry

A spare inner tube in the right size and valve type, even if you run tubeless tyres
Two tyre levers
A mini pump or CO2 inflator (or both)
A patch kit as a backup for a second puncture
A tyre boot, or a folded bank note or energy bar wrapper in a pinch, for cuts in the tyre itself
Tubeless riders: a plug tool and plugs
A multi-tool, disposable gloves, and your phone

Check the spare tube now and then. Tubes rattling around in saddle bags for a year can wear through.

Removing the wheel

Pull over somewhere safe, well off the road.
Shift to the smallest rear sprocket if it is the back wheel; it makes the wheel much easier to remove and refit.
On rim brakes, open the brake quick release so the tyre clears the pads.
Open the quick release or undo the thru-axle and drop the wheel out. For the rear, pull the derailleur back gently to let the wheel come free.
With disc brakes, avoid squeezing the brake lever while the wheel is out, as the pads can close together.

Removing the tyre and finding the cause

Let out any remaining air. Push the tyre beads into the centre channel of the rim all the way round; this gives you slack. Hook a tyre lever under the bead opposite the valve, lever it over the rim, and run the second lever round. Before fitting a new tube, find what caused the puncture, or it will puncture again within minutes.

Pump a little air into the old tube and listen or feel for the hole. Its position tells you where to look on the tyre.
Run your fingers carefully round the inside of the tyre to find glass, thorns or wire, and pick it out.
Two small parallel slits close together are a "snakebite" pinch flat, usually from hitting an edge with low pressure. In that case there is nothing stuck in the tyre.
A large cut in the tyre needs a boot inside it, or the new tube will bulge through.

Fitting the new tube

Put just enough air in the new tube to give it shape. Push the valve through the rim, tuck the tube into the tyre, then work the bead back on with your thumbs, finishing at the valve. Try to avoid using levers to refit; that is how new tubes get pinched. Before inflating fully, check all the way round that no tube is trapped between tyre and rim.

Tubeless punctures

Small holes in tubeless tyres usually seal themselves with sealant; spin the wheel so the sealant reaches the hole. If it keeps hissing:

Rotate the hole to the bottom so sealant pools there.
Push a tubeless plug (often a sticky rubber strip) into the hole with the insertion tool, leaving the ends poking out, then pull the tool out.
Reinflate and spin the wheel to let the sealant work around the plug.

If the cut is too large to plug, remove the valve and fit an inner tube. Wipe away the sealant and check the tyre for anything still stuck in it first.

CO2 or pump?

CO2 inflates a tyre in seconds, which is welcome in the rain. But a cartridge is single use, can be wasted if you fumble it, and gets very cold, so hold it with gloves or a sleeve. Butyl inner tubes tend to lose CO2 faster than air, so let it out and refill with a pump when you get home.
A mini pump never runs out but takes effort to reach road pressure.

Many riders carry both: CO2 for speed, a pump as a backup. Whatever you use, try it at home first.

Before you ride off

Refit the wheel, close the brake quick release if you opened it, and spin the wheel to check it runs straight and the brakes work. Ride gently for the first few minutes, and replace a booted tyre as soon as you can. What is in your saddle bag, and what is the worst puncture you have had to fix by the roadside? Share your tips and questions in the comments below.