Fixing a Flat Fast
Punctures are an inevitable part of sportive training; if you can’t fix them properly, you won’t get very far. Use our step-by-step guide to perfect puncture repair and you’ll be on your way again in no time.
Kit yourself out
Your puncture repair kit should include the following essential items: some feather edge patches, rubber solution, a pair of plastic tyre levers (strong and not too bendy), a piece of fine emery paper, a small, adjustable spanner if using wheels with hex nuts, an Allen key if using Allen bolt fitting wheels and, most importantly, a reliable pump.
A keyring LED is also useful if you’re riding in the dark with a dynamo. For Presta valve tubes a Schrader converter can be useful – you can then use a garage airline or car pump to inflate your tyres, but be very careful. You should always carry a spare tube too. Aside from the pump, all this should pack in an underseat bag.
Check your tyres for cuts in the tread, swelling in the sidewall, or serious wear. Tyres with cuts or swelling must be replaced. Remove any grit or glass embedded in the tread. Check your tyre pressures with a proper gauge. Tyres inflated to the correct tyre pressure will have fewer punctures and a longer life. The recommended pressures are normally marked on the tyre’s sidewall.
Use your spare
Repairing a puncture is very difficult in the rain as the patch will not stick to the tube. Fit the spare tube that you always carry! The spare tube is also essential if a tyre blows off a rim, or if the tube is cut by the valve hole.
Bands and beads
Kevlar banded tyres will resist punctures better than those without a puncture resistant band. But don’t confuse Kevlar banded tyres with Kevlar beaded tyres, which can easily be folded.
1 Find the puncture
Starting at the valve, check all the way around the tyre’s tread to find the cause of the puncture. Remove any glass or grit that you spot. Even if you find one possible cause, continue checking the tyre until you get back to the valve. Use this information when checking the tube.
Tip: When taking the tube out of the tyre, note which way the tube was around in the wheel – this will help identify the position of the hole in the tube once the position of the object in the tyre causing the puncture has been found.
2 Removing the tube
Let the air out and remove the valve, retaining the ring if fitted. Push the valve up into the tyre. On the side of the wheel opposite the valve, slip a tyre lever under the tyre’s bead and a further tyre lever about 5cm away. Pull the nearer tyre lever towards you, lifting the tyre’s bead over the edge of the rim. Continue until the one bead of the tyre is completely free of the rim. Pull the tube out. Remove the tyre completely from the rim. In most tyres this can be done by hand unless the tyre is exceptionally tight.
3 Inflating the tube
Inflate the tube and listen for air escaping. Passing the surface of the tube over the lips is a favourite trick. If the hole still cannot be found, re-inflate the tube and pass it through a bowl of water until you spot escaping bubbles. Then dry the tube before proceeding to the next step. Take care not to twist a push-fit pump on the valve – the pump should be pushed on straight and pulled off with a single straight pull. The stem nut can easily be broken off if the pump is twisted sideways.
4 Preparing the tube
Select the correct size of patch – use a bigger rather than smaller patch if in doubt. Roughen the surface of the tube around the hole with emery paper. Ensure that any moulding marks are flattened completely. Apply one drop of tyre cement and spread it thinly with your finger over a 2cm circle around the hole. Allow to dry.
5 Patching the tube
Apply a second thin layer in the same way. Once again, allow this to dry – the rubber cement will change from shiny to matt. Inflate the tube slightly – this will help to highlight the position of the hole. Firmly press the patch into place after removing the backing foil. If there’s a thin cellophane backing on the patch, it can be left on. Dust the repair with chalk, talcum powder or road dust to prevent it sticking to the tyre casing.
6 Check the casing
Before refitting the tube, double check the tyre casing from inside for the cause of your puncture. Placing the tube over the tyre will help you to discover the position of the puncture. Run your fingertips carefully around the inside of the tyre to feel for the cause of the puncture and remove.
7 Refitting the tyre
After repairing the tube and checking the tyre for glass/thorns, refit one bead to the rim. Slightly inflate the tube and refit it to the rim, putting the valve through its hole first. Starting at the opposite side of the rim to the valve, use your thumbs to lift the tyre’s bead over the rim. Work around the rim until there’s just one small section of tyre left. Push the valve up into the tyre and then, using your thumbs, ease the remaining section of the tyre’s bead over the edge of the rim.
8 Making final checks
Check that the tube is not trapped between the rim and the tyre bead. Inflate to about 20psi. Check that the moulding mark around the tyre follows the rim evenly all the way around. If not, deflate a little and ease any high spots down and pull low spots up until the bead is fitted evenly. Inflate to the recommended pressure and check once again that the tyre’s bead is still seated evenly and that the tyre is not lifting off the rim at any point. Finally, check that the tread is running reasonably straight by spinning the wheel. If not, deflate the tyre and start again from the beginning of this step.
|Discover more great features on every aspect of cycling and get ahead of the pack with a subscription to Cycling Plus magazine. Prudential RideLondon participants can click here for an exclusive offer.