How To Change a Flat

It Happens To Everyone
If you never get a flat tire while riding your bicycle, chances are; You have a Flat Tire Fairy who precedes you, making sure your tires are properly inflated before every ride, smoothing the edges of potholes and picking up bits of glass and other trash before you ride over them. Chances are you don't have a Flat Tire Fairy, so learning how to manage to change a flat tire is probably a good idea.

So What Do I Do?
First, knowing how to properly inflate (or re-inflate) a tire is critical. Secondly, know how to get the wheel with the flat tire off your bike. We have two Tech Tips sections that address this, How To Air A Tire and That Quick Release. If the wheel bolts onto your bicycle, you are going to need some tools not included in the section on That Quick Release. Bolt on wheels are found on kid's bikes, and less expensive department store bikes, as well as single speed bikes, or bikes with an internally geared hub like a 3 speed bike or a Breezer city bike. You need a pair of properly sized wrenches to remove the wheel nuts, not pliers, and adjustable wrenches are not recommended because they can round off the nuts if not used with extreme care. If you cannot remove the wheel nuts, changing the tire is impossible. Also, when replacing a rear bolt on, internally geared or single speed rear wheel, incorrect chain tension can cause other problems. If you read this and decide that removing the wheel is too complex for your comfort, please bring your bicycle by Bicycle South, we can take care of you!

But Before You Take The Wheel Off
Find out where the flat is first by visually inspecting the tire. If it is a small pinch type flat (when you fall into one of Atlanta's Famous Giant Potholes) when the tube gets pinched between the tire and the rim, you might see a scuff on the sidewall of the tire, but it is not likely you will see anything. What you are looking for are bits of glass, thorns, pieces of metal - anything that may pierce your replacement tube on installation and inflation OR has damaged the tire past repair. Look for tears in the tire. If the damage to the tire is great enough that the casing (material under the rubber) is damaged, your tire is not reliably repairable. Also, check out the rim. We've seen cracks near the spoke heads on very old wheels that can cause the rim to pinch the tube, even through the rim strip. If your tire or wheel is damaged beyond repair, you will want to know that before you try and replace the tube!

OK My Wheel is Off - What Next?
If you've gone ahead and gotten the rear wheel off, you will need some way to take the tire off the rim and you will need to replace the tube, or patch the existing tube. You will also need to inspect the rim and the tire from the inside as well (if you are putting the old tire back on) to make sure that you've eliminated the cause of the flat. Nothing is more frustrating than putting everything back together and having another flat tire - it happens!

Necessary Tools and Equipment

With a frame pump, tire levers, patch kit, and a spare tube, you're good to go!

Tire levers help you in getting that tire off the rim. Since tires and rims are not consistently, perfectly all sized you may not need tire levers and can just use your hands or you may wrestle with that tire and wheel trying to get them apart. It's helpful if the tire has been on and off the rim a few times, because the metal bead inside the tire will stretch a little, and it will be easier. However, sometimes tires are a really loose fit and can actually not seat correctly on inflation after replacement and blow entirely off the rim. A visual inspection is critical! Exceptionally tight tires that require the strength of 10 men to remove, or exceptionally loose ones that don't even look like the right size when you put them back on, are generally the exception, not the rule.

What's happening here is one bead of the tire is being removed from the rim. As you can see, one tire lever (tire levers come in pairs or threes) is being used to lift the bead of the tire off the rim, the other to pull one side of the tire off the rim. Remove one side of the tire at a time. Start removing the bead 180 degrees (on the other side) of the valve stem of the tube. Once you have one bead over the rim, the whole way, grasp and pull. The tire should come off with tube neatly in it, in your hand.

If you aren't sure why you flatted, or are on your second flat on the same wheel, it may be helpful to partially inflate the tube and see what is causing the flat. Note the orientation of the tube inside the tire before pulling the tube out. There is a trick to this on reinstallation we will point out, that can save you time in the future. Inflate the tube slightly (a hand pump is useful here) and note how quickly it deflates and/or listen for air rushing out. If you cannot replace your tube and have to resort to patching it, this operation is critical! Tubes can get punctured in more than one place, sometimes bits of things have worked their way into the inside of the tire and are lurking there waiting to cause another flat, or a spoke could have pierced the tube from the inside because it is broken on the rim strip is damaged or twisted. It all sounds terrible, but if you get used to thoroughly investigating the problem, you are more likely to successfully replace that tube and ride off happily into the sunset. Plus, you can impress your friends with your mechanical know how!

About Patching Tubes
We won't tell you that it's bad - but patching the tube has its drawbacks. Skinny, high pressure tires have narrow diameter tubes. Sometimes it's hard to get that patch to stick and seal on a narrow tube and if you are inflating a tire past 65 psi, sometimes that patch just won't hold. A big hole in a tube is impossible to patch. Tiny holes in tubes may be hard to find while sitting there on the side of the road trying to fix a flat. Bicycle South doesn't patch tubes, because we can't be sure we've fixed the leak. We replace them. If you are being thrifty, patch at home where you can use a water filled sink to look for leaks (bubbles come out of even the smallest holes in a slow leak when you inflate that tube and put it in the sink), the patch cement has time to cure (if you didn't use glueless patches) and you can inflate the tube overnight and make sure it's still full in the morning. If you are successful, you may still have a useful replacement tube, if not - well you didn't ruin your ride. Lastly, if the valve of the tire is damaged, or the valve is no longer properly affixed into the tube, patching will do you no good whatsoever! Carry a spare tube on the bike. Some people even carry two!

Inspection Passed!
OK, there isn't anything on the inside of the tire (you've run your fingers inside the whole thing, braving the possibility of a pricked finger to make sure you got everything out), your tire isn't damaged, the rim strip is still preventing the spokes from poking the inside of the tube, and you know where the hole in the tube is. So you are ready to put it all back together with a brand new tube.

A Little Puff…
So you take your neatly coiled, flat, tube out of the bag behind your seat, the box on the shelf in the garage, wherever you put it when you brought it home. It doesn't look like the one you just took out of the tire, but you know the size is right (because you read the box and matched it to the tire size, or you asked us!). How do you get it back in the tire? Its flat, its uncooperative and isn't a nice round shape like it needs to be. So put in a little puff of air, or Co2 or whatever you use to inflate a tire. Just a little - because that tube does not have a tire to constrain it's shape, add too much air, and it won't fit in the tire. A little bit of air and it orients nicely, with the valve located on the inside. Here is the first trick that will save you untold time playing detective with flat tires. When you are putting the tube in the tire, orient the valve right below the tire label.

Mounting The Tire
Done right, you are on your way. Done wrong and you can have all sorts of problems, some of them leading to a very large noise and a search for that second spare tube. It's easy if you follow these instructions. Everyone makes at least one mistake doing this, but mistakes are to be learned from right? Hopefully we can help you not make any of the common mistakes!

Put the valve in the hole first - BUT - don't pull it through all the way. If you have Presta style valves, do not put the threaded piece on the valve stem at this point. At all. Even if you are afraid of losing it. Pulling the valve stem down tightly through the hole will not help the tire seat properly on the rim. Chances are some bit of tube near the valve stem will get stuck between the bead of the tire and the rim and when you inflate it, will blow apart with an impressive bang (or just leak quietly). A tube with a big tear in it from being caught between the tire and the rim will never be repaired. Ever. So line the valve up nice and straight with the hole, but don't pull it through tightly. Mount one bead first. You should be able to do this with your fingers. It's the second bead that will be more of a wrestling match. You want to avoid the use of tools to get the beads on, because you are more likely to damage the tube. Since there isn't any tension on the tire, the first bead should go right on. Start at the valve stem. If you've puffed up the tube to get it to fit nicely in the tire, prepare to let that air, or some of that air out. It'll make getting the second bead of the tire on the rim much easier, ensure proper seating of the tire, and help avoid pinching the tube between the bead and the rim.

Once you've got one bead on, make sure the valve is still straight and start putting the second bead on. Start at the valve stem though! That's right, start at the valve stem and work the bead over the rim from both sides. Remember, don't pull the valve stem all the way through, just make sure it is straight! You may find it necessary to let all the air out of the tube at this point, but that's OK, if you got everything together, it's not going anywhere.

The Last Little Bit!
This last little bit can be a real bear if the tire is new and/or tight or you don't have a lot of hand strength. A couple of things to keep in mind. If the tire is the right size, it will go on. Another thing - you don't really want to use a tire lever to pop that bead over unless you really have to, cause it is likely to damage the new tube. If you really are struggling with this part, practice with a tire without the tube. It doesn't hurt it and it's a good thing to learn to do at home on your own time. It's less about having very strong hands, than about applying the force in the right place. Working that tire over that last little bit can be tough - and if you are very, very, careful you can use a tire lever - just know what can happen if you pinch that tube between the tire lever and the bead of the tire or rim.

Another Inspection
It never hurts to look and make sure there is no tube sticking out under the bead. Push back, like the picture, on both beads, on both sides of the tire, all the way around. It only takes a second and prevents the possibility of flatting again before you even get going because you got everything together - but the tube got stuck under the bead!

Fill Slowly And Check
Since this is your bike and you aren't likely to have tons of spare tubes lying around, take your time and make sure the tire is seated properly on both sides of the rim during the inflation process. If a big chunk of tire is sticking up unevenly, you need to let the air out quickly before the tube works it's way out under the tire, and over the rim and explodes with a deafening bang. You can pull a little bit more valve stem through the rim at this point, but there should be enough of the valve sticking through to get the pump head on for inflation (this is your second trick to guarantee success!). We'd like to make a few observations about the blowing-the-tire-off-the-rim phenomenon. It happens, even to us at the shop. It's more likely to happen when you use an air compressor that fills the tire very quickly before you make sure it is evenly seated on the rim. Pay attention! If you change a lot of flats at a bicycle shop, you may not be concentrating as much as you would if it is on your own bike, on your own tire, on your own time. If you use Co2 on the road - but a Co2 charger with a trigger on it, so you can control how much Co2 gets put in at once. When we use a floor pump to air up a suspect tire, we take plenty of opportunity to make sure that the tire evenly seats along some reference point on the tire as we are inflating. Removing some air and manipulating the tire often puts it right. Sometimes tires will even themselves out as they are inflating. If you think it's not going to, better to let the air out, pull on a low point of the tire and tube assembly with your hands and try again.

(Picture of properly orientated tire and tube on rim)

What About That Valve Stem?
Remember what we told you about the valve stem? Well if it was lined up straight, it should have put itself through the tire properly once the tire is completely inflated. You might have had to pull it a little bit through to air the tire, but it should be nice and straight and properly stuck through. If you have the little threaded nut that goes on the Presta valve, you can put it on now.

You should be able to put the wheel back on and ride off into that sunset now.

When To Not Just Change A Flat
Most people can follow the procedure above and ride away happily. The interesting thing is, the more you ride, the more you will have a chance to get a flat tire, the more opportunities you have to learn how to change it. You don't have to be a mechanic, competent or otherwise to change a flat. It's nice when we do it for you, but it's not that hard, and knowing how to change a flat could save you or someone else a very long walk home. Bicycle shops tend not be always open when you need them, so have what you need to change the flat before you need to!

There are some extenuating circumstances though, where you may need More Knowledgeable Help. The first is damaged or worn tires. If you ran over something big and nasty and that tire is badly damaged, you should replace it! We mentioned damaged tire casings. A tire casing can be damaged by something that doesn't create a small puncture through the tire, but by a tear in the tire, or a really large nail. This can happen from road hazards like the aforementioned potholes as well as a piece of glass or rock. If it happens to you when riding, don't just replace the tube and hope. Chances are that tire will develop something like a hernia, with the tube poking out of the cut or tear in the casing. You can temporarily repair the tire by "booting" it from the inside. Duct tape, road trash, power bar wrappers, a piece of patch. Be imaginative. Tires rot. Tires are made of rubber, which is attached to a fabric casing. Even if you keep your bike inside, rubber is natural and eventually gets dry and deteriorates, therefore comes off the casing. A tire with dry rot can be perfectly new, but once you've got rubber coming off the casing, that tire will no longer be reliable. We see tubes herniated through sidewalls and beads that separate from the tire. You need a new tire! No roadside repair will get you home on a rotted tire that has self destructed.

Rim strips sometimes wear. Rim strips on a lot of bikes are simply a rubber liner that fits over the spoke heads on the inside of the rim and prevents the tube from being punctured. Since we've already established that Rubber Is Not Forever, check the rim strip, make sure it is not twisted, broken, punctured or has lost it's resiliency. If you have a fabric rim strip, make sure the adhesive hasn't dried up and the rim strip is still stuck where it needs to be. Now, not all bicycles have wheels with rim strips. Some of the high end wheel sets that come stock on expensive bikes do not. Ask us if you have a question!

Lastly, rims can get damaged. Rims are simply a welded or tacked hoop of metal held to the hub by spokes and they take a lot of beating. Sometimes the seams can crack, sometimes the tension of the spoke can cause the rim to crack where the spoke goes through. Age and impact related wear can cause a rim to fail. Sometimes it's a sneaky thing, a little crack on the inside that pinches the tube. Inspect the wheel to make sure a broken spoke isn't puncturing the tube from the inside as well.