Road bike maintenance - tyres
Time: Ten to twenty minutes
- Feather edged patches
- Tube of rubber cement
- Tyre levers
- Wheel nut spanner (if you do not have quick releases)
Check your tyre pressures every week using a proper gauge (Zefal make good ones) or good track pump with an integral gauge. Tyres inflated to the correct tyre pressure will suffer from fewer punctures and have a longer life. Find the recommended pressures are marked on the sidewall.
Inner tubes on road bikes are generally fitted with Presta valves. These have a narrow diameter stem with a small knurled nut on the end. To inflate a Presta valve tube, remove the dust cap (if fitted) and unscrew the valve stem nut a couple of turns. If you're having difficulty inflating the tyre, depress the knurled nut just to release the valve. You can use a screw on hose with your pump, or more likely, your pump will have a push-on adapter. It's easier if you sit the valve at the top of the wheel - just so that you don't have to bend over so far!
You can avoid many punctures by simply checking your tyres regularly for cuts or wear in the tread and bulges or damage to the sidewalls. Replace tyres if they are worn or damaged. Pick out any bits of grit or glass that may be embedded in the tread. Small cuts may be filled with Super Glue or patched from the inside.
Always carry a spare inner tube for use 'on the road' and use that to replace the punctured one. You can repair the puncture when you get home. Do ensure that you remove the cause of the puncture from the tyre before you fit the new tube! Besides, if you have a seriously damaged tube, it may not be repairable and repairing a puncture in the rain is very difficult, as the patch will not want to stick to the tube.
'Glueless', self-adhesive repair patches work reasonably well at lower pressures on the larger diameter, lower pressure MTB tubes but they are not so reliable when used on high-pressure road tyres. Only consider them as emergency repairs with road tyres. A good rim tape is essential to prevent punctures on the underside of the tube. The most reliable are the Velox cloth rim tapes - but do ensure that you buy the appropriate width for your rims.
Tyres with a Kevlar band under the tread will resist punctures better than those without a puncture resistant band. (Don't confuse Kevlar banded tyres with Kevlar beaded tyres. A Kevlar bead makes the tyre a little lighter and makes it easy to fold up and carry as a spare.
Repairing a puncture
Puncture cause checks
Removing the tyre
- Remove the wheel from the frame
- Before removing the tyre from the rim:
- Check the tyre carefully all the way around to see if you can spot the cause of the puncture.
- Use the valve or tyre label as a reference point.
- Remove any foreign objects that you find (glass, flint or thorns etc) - but continue checking the tyre for further until you get back to the valve.
- If the tyre is cut badly it will probably need replacing at the soonest opportunity.
- If the cut is very large and you are out on the road refer to Emergency Repairs.
Finding the hole in the tube
- Let out any remaining air from the tube and remove the valve-retaining ring.
- Push the valve up into the tyre.
- Opposite the valve, slip a tyre lever under the tyre's bead and a further tyre lever about 5cm to one side.
- Pivot the lever on the edge of the rim; push the free end down towards the hub, to lift the tyre's bead away from the edge of the rim.
- Repeat with the second lever.
- Remove the first lever and insert it another 5cm along the rim and continue until one side of the tyre is removed from the rim.
- Pull the tube out of the tyre and note which way round it sat in the wheel.
- It's not necessary to remove the tyre from the rim completely.
- Run your fingers along the inside of the tyre to check that nothing is still penetrating the casing.
Puncture on underside of tube
- If you found the likely cause of the puncture (as in stage 1 or stage 2) this will help you to locate the hole in the tube.
- Inflate the tube and listen for air escaping.
- Tip: Pass the surface of the tube over your face to feel the air escaping
- If this doesn't work, re-inflate the tube and pass it through a bowl of water.
- Bubbles will indicate the hole.
- Dry the tube before proceeding further to step 6.
- If you find the hole on the underside of the tube, this indicates that the puncture was caused probably by a misplaced rim tape or untrimmed spoke head.
- Check around the inside of the rim and make sure that the rim tape properly covers the spoke holes or that no spoke ends are protruding up above the inner surface of the rim.
- Any protruding spokes need filing down flat, beneath the rim's inner surface.
Repairing the tube
- A 'pinch puncture' or 'snake bite' is indicated by two small holes, fairly close together and is caused by the tube being trapped between the tyre and the rim when riding over a sharp object or edge.
- This is often an indication that the tyre was not inflated hard enough. Check that the tyre's sidewall is not cut - if so refer to Emergency Repairs.
- Check your rim for damage too.
- You may be able to straighten it with small adjustable spanner if necessary, or you may need new rim.
Refitting the tube
- Roughen the surface of the tube around the hole with sandpaper.
- Ensure that any moulding marks are flattened completely.
- Apply a drop of tyre cement over the hole and spread it thinly with your finger over a two-centimetre circle (or slightly larger than your repair patch) around the hole.
- Allow to it dry.
- Apply a second thin layer similarly.
- Once again allow to dry - the rubber cement will change from shiny to matt.
- Remove the backing foil from the patch and apply the patch firmly to the tube, making sure that the edges are stuck down well.
- A pinch puncture will probably need a large repair patch.
Final tyre fitting
- Thin cellophane backings can be left on the patch but thicker patch backings will need to be carefully removed.
- Tip: Fold the tube in half at the patch to tear the backing. Then remove the backing from the middle to the outside of the patch.
- Dust the repair with chalk dust or road dust to prevent it sticking the tyre casing. Refit one bead of the tyre to the rim leaving the other bead over the rim's edge.
- Inflate the tube slightly and refit it to the rim putting the valve through its hole first.
- Don't inflate the tube hard to check that the patch has adhered properly - this will simply lift it off.
Inflation and essential checks
- Start at the valve and use your thumbs to lift the tyre's bead over the rim.
- Work around the rim steadily until there's just one small section of tyre left to fit.
- 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.
- Avoid using tyre levers unless absolutely essential. You are quite likely to pinch the new tube with them!
- Check that the tube is not trapped anywhere between the rim and the tyre bead.
- Loosely refit the valve-retaining ring.
- Inflate the tyre to about 20 psi.
- 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.