PUNCTURE REPAIR - THE DEFINITIVE GUIDE TO FIXING A FLAT

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Stills taken from our 'puncture repair' instructional DVD which is available for £3.97 from our ebay store

INTRODUCTION

Fixing a puncture is not rocket science and i'm certainly not about to pretend otherwise, BUT, like most things there's still a right way a wrong way to do it….....

REMOVING THE WHEEL, TYRE, AND INNER TUBE

The first thing to do is support the bike with the wheels off the ground - a repair stand is great but if, like most people, you haven't got one or you happen to get a puncture out on a ride then its just as effective turning the bike upside down onto the handlebars and seat. DON'T do this like i used to which was to be clever and flip it over on the back wheel because every time you do this it scrapes the saddle and wears it through it in no time. Instead, lift the bike up and place it on the ground, and if you've got a cloth or towel to put it on - even better.

Now before you take the wheel out its worth having a quick look for obvious puncture culprits such as thorns, glass or nails -  if you do find anything obvious then mark the tyre and you'll be pretty sure where the puncture is before you even start. Whilst your in tyre checking mode it’s a good to time to inspect the other tyre as well – it may not have a puncture, but it could have a sliver of glass or wire working its way through the tyre ready to give you a puncture the next time you go for a ride. Keep an eye out for wear and damage as well, if you do find any rips or bulges, or the casing has frayed then don’t take any chances – replace the tyre.

Now sods law dictates that you will have a puncture on the rear wheel because it's a bit more hassle to fix - so if this is the case with yours change the derailleur to the smallest cog on the back and the biggest ring at the front and this will just make it easier to get the wheel in and out. Next make sure that the tyre is deflated completely. Most road bikes now have presta type valves like this so to let the air out unscrew the tiny valve nut a few turns then press it in to release the air. If you happen to have an old style schrader valve like the ones you find on car tyres press in the little central rod to release the air.

With the tyre fully deflated you can take off the wheel by undoing the quick release and easing it out if it's hanger. If your old trusty steed has still got axel nuts then undo them with a ring spanner rather than risk rounding them off by using an open ended spanner – and NEVER be tempted to try to undo them with pliers. On bikes with wider tyres you may need to undo the quick release on the brakes first, but with most road bikes the deflated tyre should pass through the brake blocks okay.

The bead of the tyre has a smaller diameter than the rim of your wheel - and this is great because it stops the tyre falling off the rim every time you go for a ride. However, it does make for varying degrees of difficulty when removing a tyre – so to make life a bit easier go round and push the tyre beads into the centre of the rim. This should then give you a little more slack at the point of removal. The best place to start levering the tyre off is a few spokes away from the valve so work round to that point. The ideal situation for getting the tyre off the rim is to lever it off with your hands because there is less chance of damaging the inner tube this way. However, this method only tends to work on wider mountain bike style tyres because they have a bit more give, and even then it won’t work every time. On the thinner, high pressure road tyres it's virtually impossible so you'll have to use tyre levers. I find the individual nylon levers work best - they are light, they have spoke hooks (which eliminates the need for you to have three hands), and they clip together so you don’t lose them. You can get single ‘quick release’ style tyre levers but to be honest i’ve never really got on with them.

Insert the first tyre lever rounded end first about 4 or 5 spokes away from the valve. Insert it in line with a spoke and make sure it’s the right way round so it hooks the tyre bead. Take care not to pinch the inner tube as you hook it under because this is a sure fire way of getting another puncture before you've even fixed the first. Lever the tyre off the rim and hook the lever onto the spoke to hold it in place. Move 2 or 3 three spokes away from the valve and do the same thing. The tyre may start to come off at this point, but if it doesn't then move along and put another lever in. The middle lever will now come out and the rest of the tyre should come off as you run a lever round between the bead and the rim. Now carefully push the valve out of the hole in the rim with your fingers, and don’t forget to remove the valve retaining nut first if you have one. Now you can pull the tube out of the tyre. Note - if you keep a track of which way round the tube went and leave the tyre exactly where it is on the rim then this will help when you come to finding the puncture culprit.

LOCATING THE PUNCTURE

To locate the puncture you will need to pump the tube up first and it's perfectly safe to inflate it to about double its normal size – just be a little careful if you use lightweight latex tubes as these can pop if you inflate them too much.

Now believe it or not there are three types of punctures:

1 – The slow leak - which can take hours or even a day or two to go down

2 – The faster leak - which goes down fast enough for you to watch it deflate

3 – The pinch flat or 'snakebite' - which deflates faster than it took you to read this sentence

.....and to see which type you've got just listen for the hissing as you go round the tube. A good trick here is to wet your top lip a little -it will go cold as soon as you go over the hole. Once you've found the puncture mark the hole with a big cross – you can use the crayon supplied in your puncture repair kit but i prefer to use a marker pen.

Finding a pinch flat should take about two seconds because air will be flying out of the tube faster than you can put it in. You get these types of punctures when you hit a kerb or rock hard enough to pinch the tube between the tyre and the rim, that’s why it leaves two holes side by side, and that's why it’s sometimes called a 'snakebite'. I always replace the tube if i get a snakebite but it’s personal preference so it you want to patch it mark the two holes again.

With a slow leak the first thing to check is whether the valve is leaking by submerging it in a bowl of water – no bubbles equals no leaks!  If it is leaking then it’s not worth messing around, for the price of a new tube, buy a new one. If the valve is okay then go round the rest of the tube to find the leak. I only use the water bowl method as a last resort because you can’t patch a tube unless it’s completely dry and ideally i don’t want to be faffing about drying it off. When you’ve found the hole, dry the tube and, and mark it’s location with a big cross

Now you’ve located the puncture you need to find what caused it, and just so long as you remembered which way round the tube was in the tyre then matching up to the tube to the tyre should point you to where the culprit is. Be very careful not to cut your fingers on the offending item as you feel for it! If you can’t find anything then go round and check the whole tyre – and this job is best done with the tyre off the rim completely. It should just pull off the rim with your hands but if it’s stubborn coax it off with a tyre lever.

Once you’ve found the offending article then you need to remove it, and because it probably went in pointy end first it’s gonna be easiest to remove it the reverse way it went in (i.e. push it from the inside out). Use whatever is best for the job – tweezers, long-nose pliers, etc but make sure you get it all out. If the puncture was on the inner diameter of the tube then it’s probably been caused by something sharp on the rim. The rim tape is there to prevent punctures from the rim so make sure that it’s in place correctly and in good condition. If your in any doubt then replace the rim tape. You have a choice of plastic tape (which comes in a ready made hoop), or cloth tape (which is adhesive backed, comes on a roll, and is a little easier to fit).

To fit plastic tape line up the valve hole and then feed it all the way round the rim. When you get to the end you need to stretch the last bit into place – use a tyre lever, and it should just snap on nicely. For fitting cloth tape start at the valve hole and then just work your way round - it should be cut to the right length so it just overlaps the end slightly.

FIXING THE PUNCTURE

For fixing a puncture you will need, unsurprisingly, your puncture repair kit and in there should be a little piece of sandpaper will you use to rough up the area around puncture. Before you get sanding squeeze all the air out of the tube and then screw up the valve nut to stop any getting air getting back in again – this will then give you a nice flat tube to work with. Place the tube on flat suface and start sanding the area where you intend the patch to go - this is where using a large cross for marking the puncture helps because it will still indicate where the hole is even if you have rubbed most of it out. Incidentally, the reason why you’re doing this is to provide a good, keyed surface so the glue sticks properly. If your patching over a seam line on the tube then make sure that you sand the line down otherwise it’s going to provide a route for the air to escape. Once your finished don’t be tempted to touch the area you have just sanded because the natural oils at the end of your fingers will contaminate the area. It all sounds a bit like overkill, but if you don’t do this bit properly then your likely to be rewarded with a patch that doesn’t stick.

Note - only patch holes smaller than about 3mm in diameter. If it's bigger than that there is a good chance that the patch will fail, and you will be back to square one.

With the area now meticulously prepared choose a suitable patch from your kit. Then grab the glue, break the seal with the cleverly designed top, and squeeze some on. Spread it around with a clean finger or even better a clean object that isn’t your finger – and your aiming for a fairly thin coat that is bigger than your patch. Leave it a few minutes to dry and you’ll know when it’s dry because it won’t look wet and shiny anymore. Don’t let impatience get the better of you and put the patch on when it’s still wet, and don’t touch the glue to ‘see how it’s doing’ because if you do, the patch just won't stick as well.

Peel off the foil from the patch but leave the top cellophane or paper layer in place for the moment, and be careful not the touch the patch surface. Place the patch squarely on the tube and press down firmly in the centre working out to the edges. Having the tube on a hard, flat surface make this a lot easier. Leave it a couple of minutes before touching it, then if you wish you can remove the plastic cellophane. The cellophane should be scored in the middle which will then allow you to peel it off from the centre out. If yours is not scored then don’t try to peel it from the outside as it’s likely to lift the patch off. Your better off just leaving it as it won’t do any harm being left on the tube.

To stop the patched area sticking to the tyre you need to give it a dusting of french chalk (found in the kit). Most puncture repair kits have a little grater on the bottom of the box for this chalking job but the're about as useful as a chocolate teapot, so you will be considerably older by time your done. A much quicker way is to get some talc or baby power and sprinkle some on the area, or even better put the inner tube in a bag with some talc give it a quick shake and you’ll have the whole tube covered which will ensure it’s not going to stick anywhere. If you are taking the talc bag approach just beware that some talc that is branded as 'baby powder' actually contains corn starch – don’t use this stuff because it tuns into a paste when it gets wet and will eventually rot your tube and tyre.

Note - You can get lightweight self-adhesive patches now that get rid of the need for any glueing. Although they may seem like a good idea they don't stick as good as traditional patches and therefore really aren’t a permanent fix. The only time i can see them having some merit is when you're fixing a puncture on a trail and you just need it fixed to get you back home.

REINSTALLING THER TUBE AND TYRE

Now your ready to reinstall the tyre and tube so if you took your tyre right off the rim put that back on first. Beware because alot of tyres are directional these days so if yours has an arrow on it showing the direction of rotation make sure you install the tyre right way round. Thread one side of the tyre onto the rim, leaving the other side open so you can get your tube in. The last bit should just pop on with your hands but if your struggling use a tyre lever. Next put a little bit of air in the tube - just enough to give it a bit of shape and then screw up the tiny valve nut. Place the valve into the hole in the rim, and if you have one screw on the retaining collar most of the way (this will stop the valve falling back out again or moving)
 
Now thread the inner tube into the tyre and your aim is to have the tube under even tension throughout the tyre so it’s not being stretched at all. If you do end up with too much tube flapping about at the end don’t be tempted to just stuff it in – instead, take the tube out and start again but this time push it towards the valve a little more as you insert it. Now you can push the second side of the tyre over the rim. Start at the valve end and work round using your hands. The last bit is gonna be a bit tough but you should be able to roll the bead over the rim with your thumbs. If you have a very tight fitting tyre or unusually weak thumbs then as a last resort use a tyre lever but be careful and use the back edge of the lever to reduce the chances of  pinching the tube. Check that the tyre wall is all seated properly and the tube is not trapped under the bead anywhere and then you can refit the wheel in the reverse order it came out.

Then its just a case of pumping the tyre back up to pressure. For road tyres that’s usually 85-100 psi, and for mountain bike style tyres it’ 35-50psi - but always check the maximum limit (which will be written on the tyre wall). Finally, with the tyre up to pressure spin the wheel and look for any glaring high and low spots on the tyre. If yours is obviously out of shape then deflate the tyre and make sure the tyre is seated properly where the high spots are. It's common for a high spot to be where the valve is so if this is the case with yours undo the valve retaining collar and push the valve up as you gently push the tyre walls down – this should sort the problem.

Pump the tyre back up to pressure and check how it runs. All that remains to do is to make sure that the valve retaining collar is screwed down fully, the tiny valve nut is closed, and the dust cap is on – and then your done!

I hope you found this guide useful. If you did, please take a couple of seconds to vote below. thanks!

You can also see exactly how it's all done in close-up detail with our easy to follow step by step DVD, which is available from our ebay store - just click on the link below.

ebay store

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