Mending a Puncture

Mending a Puncture

Tools required:

14 or 15mm Spanner (depending on the size of your bicycle wheel nuts, if applicable)

Pump

Tyre levers (min 3)

Patches and rubber solution

fine sandpaper and chalk

bucket of water

tweezers

STEP ONE: Removing the wheel from the bike

Position the bike to work on it, the ideal thing if you happen to have one is a workshop stand, these make life so much easier, but if you don't have one then you got two alternatives, first one is to get someone to hold the bike for you or turn it upside down, if you are going to turn it upside down just be aware of anything protruding on your handle bars and protect your seat, and don't for get you are working upside down.

You'll need to remove the wheel from the bike, generally there are two ways to do this depending on the type of wheel you have, if you have wheel nuts these can either be 14mm or 15mm and you'll need an appropriate spanner to loosed the nuts, normally it is not necessary to completely remove the nuts, just loosen them enough to allow the wheel to be removed, the less parts you take off and leave to roll around the better. The other type is a quick release lever, where you simply open the lever and undo a few threads.
If you are removing a front wheel this is relatively easy as the wheel normally just drops out of the fork. Depending on the type of brakes you have you may need to loosen these in order for the wheel to dropout. If you have cantilever, side pull, or V-brakes these are usually operated by a cable, however don't undo the cable, normally there is no need to do this and you will have to set your brakes back up afterwards which just makes the job longer, Cantilever and V-brakes usually have a connecting cable known as a straddle wire (Cantilever) or a cable pipe (V-brakes), simply squeeze the brakes together and pull out the cable, this will allow the brakes to open up wide enough for the wheel to be removed. If you have side pull brakes normally found on road bikes then some models do require the cable to be undone, however some have a special lever which allows the brakes to open up.

If you are removing a rear wheel it can be a little more complicated as you will have gears to contend with, normally derailleur gears are very easy to work with but a lot of people get flustered with them and it is usually down to how the chain sometimes tangles when you remove the wheel, if you take note on how you remove the rear wheel then you should have no problems putting it back.

If on the other hand you have a bike with internal gears then it can be a bit more tricky, first of all you'll need to undo the gear toggle chain, then undo the wheel nuts, sometimes there may be chain tensioners but just take particular note of how the wheel comes out then you should be ok.

STEP 2: Removing the Inner tube.

Assuming you now have the wheel removed and the tyre in completely flat then we can noe go ahead and remove the inner tube, generally there is no need to completly remove the tyre, you only have to put it back and you just make more work for yourself, so using your tyre levers start to lever off one side of the tyre, by using proper tyre levers they will hook around your spokes to enable you to work the tyre easier, so with one side of the tyre off the rim, remove the inner tube, if you are working on a road bike, childs bike or an older model you may have a presta or woods valve, before you can remove these tubes you need to undo the valve nut to allow the valve to go through the hole, mountain bikes, bmx and most hybrids usually use Schrader valves (or car type valves) which just push though the valve hole, might need a gentle tap to release them. Before you completely remove the tube make a note of the position of the tube and which way it is facing, the reason for this will be apparent in the next step.

STEP 3: repairing the puncture

Ok with the inner tube removed we need to find where the puncture is, by making a note of the position of the tube as it has come from the tyre, once we identify the puncture we then have a more accurate idea of where the puncture came from and can examine that part of the tyre.
Get you tube and inflate some air in to it, if you have a presta valve then remove the cap and undo the valve, which is a small knurled screw at the top of the valve, to release it just give it a gentle tap and then you can pump air into it.
listen carefully you may be able to hear the air hissing from the tube, if you can't hear it then get your bucket of water and submerge the tube into the water, moving it all around until you see the bubbles, then you know you have found your puncture.

If the bubbles are coming from the valve itself then you may be able to replace or tighten the valve of a woods or Scharder, but usually it will be best to replace the whole tube.
If the hole is a cut or slash then it is unlikely any patch repair will be successful, so I would recommend replace the tube, assuming the hole found away from the valve then place your finger on it and dry the area, then rough it up with some fine sandpaper, to allow the rubber solution/patch to adhere correctly, mark the hole with some chalk, now apply an even coat of rubber solution and allow it to semi dry for a few minutes, find a suitable patch then apply it to the area firmly pressing down, all around to remove any air bubbles and leave to set for about 10-15 mins, while you're waiting offer the tube up to the tyre in the same way it came out, find where you just put the patch on, now you know the area of the tyre where the puncture came in from , if the patch is at the bottom of the tube then it could be a protruding spoke head that caused the puncture internally, file spoke heads down and ensure the rim tape fully covers all spoke heads.

Generally most punctures are caused by thorns or pieces glass, so very carefully run your fingers around the inside of the tyre and look for anything sharp, this is where a pair of tweezers are handy as they are good at removing tiny fragments of glass or thorns, it is also worth running you're have all around the tyre in case anything else has penetrated the tyre, and also examine for any large cuts in the tyre.

Once the tube is ready to be fitted, inflate a little air in to it, not too much just enough to allow you to work a bit easier, then place the valve back through the valve hole of the rim, don't put on any valve nuts if your tube uses then just yet, work the tube back in to the tyre, never ever use the tyre levers to put the tube back in to the tyre as this could cause you to puncture it again.

Once the tube is in then work the tyre bead back on to the rim, ensure you don't pinch the tube, some tyres do fit very tightly and can need a bit of hand strength to get back on, however once you have the tyre back on take note of the fitting line around the tyre, as this will be your guide, you want this to be even all the way around, before you put more air in to the tube, push the valve up in to the tyre this will ensure the tube seats correctly and you don't get a budge here. Then gradually fill the tube with air, and check the fitting line in between pumps, it may be necessary to pull and push the tyre to get the fitting line even, once you have the fitting line even then go ahead and pump the tyre up to the recommended pressure which should be on the side wall of the tyre. Ensure the valve is straight and not at an angle, then you can if applicable fit the valve nut and put the dust cap back on.

And that's it, all you need to do now is replace the wheel back in to the bike. With rear wheels just test your gears and it should be a matter of reconnecting the brakes, if they are pulling to one side it could be possible that you have not centralised the wheel exactly as it was, so undo the wheel nuts or quick release, centre the wheel with the brakes pulled on and retighten.

To prevent punctures in the future there are a few things you can do, regularly check your tyres to ensure they are not worn or have any cuts, children's bikes can have a flat or worn spot in the tyre, where they have been skidding, this is a sure fire way of getting a puncture.

There are products available that can help prevent punctures, such as the Slime tyre liner, this fits in the tyre before you fit the inner tube, this create a barrier between the tyre and the inner tube, and can help prevent thorns and shards of glass from penetrating the tube causing a puncture, a regular inspection of the tyre and removal of offending items will prevent them going deeper.
Using tyres made of Kevlar or other puncture preventing material will also help.

Then there is also a solution know as slime tyre filler, it s a green substance then is inserted into the inner tube itself, it's important to note that this stuff does not prevent you getting a puncture but helps fill the hole as it happens which then prevents you from needing to mend it or walking home, you may need to put a little more air to replace any lost.
Whatever you use it's all down to checking your tyres regularly and don't forget to check your tyre pressure too, many people don't realise a tube will naturally loose air, so over a period of time you will need to top up your tyres to the recommended pressure, it will also help keep your tyres in good shape and make them last longer, and above all improve your riding experience.

Happy Riding