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What Every Cyclist Should Know About Flat Tires

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Sheldon Brown photo
by Sheldon "Tsssssss..." Brown
revised by by John "Full Immersion" Allen
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What's Inside Your Tire?

People usually think that tires are made of rubber. This is understandable, because rubber is all that you can see, but it's a serious oversimplification.

A tire is actually made up of three parts:

  1. The beads are two hoops of strong steel cable (or, sometimes Kevlar ®.)
  2. The cords, cloth forming the body of the tire, woven between the two beads. Most modern tires use nylon cords.
  3. The rubber, which covers all the other parts. The rubber on the part that contacts the road is thicker, and is called the tread.
A bicycle tire is not airtight by itself, so it uses an inner tube, which is basically a doughnut-shaped rubber balloon. The inner tube has a valve to allow you to blow it up. (Tubeless tires are beginning to appear on bicycles. They require the rim to be airtight, adding complications -- especially on a spoked wheel).


There are three types of valves in common use for bicycle tires, and there are adapters --:

Schrader Woods
Schrader valve Woods valve
Presta-closed Presta-open Presta-adaptor
Presta valve
Presta valve
Presta valve
with Schrader adapter

Schrader and Presta or Woods valves require a different type of pump fitting, but you can get an inexpensive adapter to use a Schrader pump on a Presta or Woods valve. If your tires have Presta valves, a convenient way to avoid losing this small adapter is to leave it threaded onto a valve, and carry a Schrader pump. You will then be equipped to inflate anyone's tires.

Presta tubes may be used in rims that are drilled for Schrader or Woods valves, though it is advisable to install a rubber grommet in the valve hole. A Schrader or Woods valve won't fit through the valve hole on a rim drilled for Prestas. Presta-drilled rims (except the very narrowest) may be drilled or reamed to accommodate Schrader valves.

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Types of Flats

A tire goes flat because there is a hole in the inner tube. There may or may not be anything wrong with the tire itself.

Flat tires can be divided into four groups:

  1. Slow leaks take long enough to go flat that the bicycle may actually be ridden, but the tire will need to be pumped up more often than it should. It is normal for a tube to lose air over a period of weeks. If you use high-pressure tires, you should check the pressure at least once per week.

    If you put your bike away for the winter and come back in the spring, the tires will likely be soft or flat, but this doesn't necessarily mean that there is anything wrong with them: you may just need to pump them up. It is a good idea though to hang your bicycle up so it is not resting on flat tires for a long time. They will hold the flat shape, possibly making it hard to seat them evenly on the rims.

    Slow leaks that take more than an hour or so to go down can often only be repaired by replacing the inner tube, since it may be impossible to find the hole.

  2. Punctures are caused by running over sharp things which poke a hole through the tire and into the tube. Punctures may be caused by glass slivers, thorns, nails, bits of wire or other small, sharp objects.

    The typical puncture puts a small hole in the tire, which doesn't matter. Patching or replacing the inner tube is the fix for punctures...but don't forget to remove the pointy thing from the tire before you put it back on!

  3. Pinch Cuts result from hitting stones, curbs, or sharp edges of holes in the road surface. When the tire hits a sharp edge hard enough, it compresses so that it bottoms out. The inner tube can get pinched between the rock and the rim. Pinch cuts usually put two small holes in the tube. This type of damage is sometimes called a "snake bite" because the two holes look like the wound made by the fangs of a snake.

    Pinch cuts sometimes ruin tires as well as tubes, but usually the tire will not be damaged.

    The impact that causes a pinch cut can also make a dent or "blip" in your rim.

  4. Blowouts are sudden losses of air, usually accompanied by a loud BANG! Since the inner tube is just a rubber balloon, if you pump it up outside of a tire, it will stretch bigger and bigger the more air you put into it, until it pops. The inner tube will not take much pressure by itself, it needs to be held inside of a tire to get up to full pressure. If the tire doesn't hold the tube in all around, the tube will pop.
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Wheel Removal

Warning: dirty work. Tires pick up dust and dirt. Especially in winter, rim brakes scrape black particles off wet aluminum rims. For an on-road repair, it is not a bad idea to carry a pair of light garden gloves in your toolkit. Black tights, shorts or trousers also are advisable.

It is possible to repair a flat by patching the inner tube without removing the wheel from the bicycle, and that may be faster if the hub has a brake reation arm or internal-hub gear. You then need only remove one side of the tire from the rim. The hardest part, if you leave the wheel on, is slipping the uninflated tube past the shoes of a rim brake if you can't loosen the brake.

If you are going to replace the inner tube, though, you must take the wheel off.

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Tire Removal

Before you remove the tire, take a quick look at it to see if the cause of the flat is obvious. There may be a nail sticking out, or a hole in the sidewall, or some other obvious problem. More often than not, the cause will not be obvious from the outside, but a quick look can sometimes save time.

If the tire is not completely flat, deflate it the rest of the way, by letting air out at the valve. Unscrew and remove the valve cap. Then:

Press the tire down against the ground as you do this, to let out as much air as possible.

To remove the tire, you need to pull the bead off the rim, one side at a time. The diameter of the bead is smaller than the outer diameter of the rim. As long as the tire is centered on the rim, it cannot come off. To remove one side of the tire, you need to put the bead off-center. One part of the bead needs to go down into the valley at the bottom of the rim, so that the opposite side of the bead can be pried over the edge of the rim. This can often be done by hand, but usually is much easier if you use tire levers (tire levers used to be called "tire irons", but nowadays, most of them are made of fiber-reinforced plastic.) Most tire levers have a rounded end and a hooked end.

Often, the bead will adhere to the rim. Push each bead toward the opposite side of the rim, all the way around, to make it easier to remove.

Tire levers commonly come in sets of three, because three is the most you ever need. If the rim is very narrow, the tire may not be able to sink down into the bottom of the rim at the valve, so, pull the tire out near the valve, and it will sink in opposite the valve. For a difficult tire, stick the rounded end of one tire lever under the bead, starting near the valve but not at it -- that only complicates matters.

Insert the lever right where one of the spokes lines up. Pry one side of the tire bead over the edge of the rim, then hook the end of the tire lever to the nearest spoke. Insert another tire lever two spokes away from the first, and repeat the process. The third lever goes two spokes away from either of the first two. When the third lever is in place, the middle one will fall out, and you can repeat the procedure. After some number of times, the tire will be loose enough that you can just run a tire lever around the rest of the rim to pull the whole side over.

This is the procedure for tight-fitting tires, particularly for narrow tires. Most tires will come off with less trouble.

After you have removed one side of the tire, reach in and pull out the inner tube. Remove the tube completely, while leaving the other side of the tire in place.

Inspection and Repair

Keep track of which way the tube was facing in the tire, and pump it up. You will usually be able to find the hole by the hissing sound as the air escapes. A slow leak may not make enough noise to hear, unless you pump the tube up enough to stretch it out. Tubes can commonly be inflated to twice their normal thickness or more without risk of popping them, and, as the tube stretches, the hole also gets bigger, making it easier to find. Your lips are very sensitive to touch, and if you hold the tube close to them, you can sometimes feel the air coming out. For very slow leaks, as a last resort, you can immerse the inflated tube in water and look for bubbles. Don't do this unless you need to: the tube must dry before you can patch it..

Sometimes the valve leaks, and with a Schrader valve, you can wipe spittle over the top of the valve and see whether it expands into a bubble.

When you find the hole, make note of where it is with respect to the valve hole, also whether it is on the inner or outer side of the tube.

Rim-tape failure at a recessed spoke hole, and resulting puncture
Rim tape failure with recessed spoke holes

Some rim tapes are simple strips of rubber, similar to the rubber used to make the inner tube, with a hole for the valve. These rim tapes are adequate for use in wider rims without recessed spoke holes, but must be stretched over the rim when installed. Narrow rubber rim tapes often break at the valve hole.

Better rim tapes are of fabric or plastic, and backed with an adhesive. This is especially important with a narrow rim and Schrader or Woods valve. Duct tape or glass-fiber reinforced strapping tape can be torn lengthwise to the needed width and works too. Use three or four layers. If adhesive-backed tape can't be wide enough to get past the valve, it can just stop at either side.

The rim tape must be just wide enough to fit the bottom of the rim. Too narrow, and it doesn't cover what it needs to. Too wide, and it rides up on the bead seat of the rim as shown in the photo below, preventing the tire from seating correctly. The tire will be too far out where it rides on the rim tape, and too far in at another place. It will give a bumpy ride, and there is a risk of a blowout. .

Rim tape too wide
Rim tape too wide


Tire Inspection

While you have the tire off the rim, examine the inside of it carefully. Thorns and glass slivers can hide, and may be difficult to remove. I find that pushing them back out through the tread, using a sharp instrument, is often helpful.

In addition to looking for sharp pointy things poking through, look also for broken cords or cuts in the fabric of the tire. If you find such cuts that run more than a millimeter or two, you should replace the tire when possible.

Tire Repair

If you're on the road and have a tire with a bad cut that could allow the tube to bulge through, you can make a temporary repair by installing a "boot" on the inside of the tire. This can be made of any flexible but non-stretchy material. The ideal thing is a piece cut from an old tire, because this will have the correct curved shape to begin with. I usually like to carry a strip 2-3 inches (50-75 mm) long, cut from an old tubular tire or a high-pressure road clincher. Mountain bikers sometimes use dollar bills folded over, or Mylar food wrappers.

One thing that is often tried, but doesn't work too well, is the rubber patches made for inner tubes...they are too stretchy.

A boot doesn't need to be glued in place: it will stay put just from the pressure of the inner tube against the tire.

Even the best of boots should only be considered a temporary repair. The tire will be less reliable, and you will feel a bump every time the tire goes around.


Installing a spare inner tube isconvenient in cold or wet weather, and is faster if wheel removal and repalcement are easy. Inner-tube patching is a very old, well established technology, and is quite reliable if done properly. You can patch the punctured tube when you get home.

Some patch kits have thick patches and a grater. Don't use these on bicycle inner tubes. Patch kits made for bicycles contain thin patches with rounded contours and tapered margins, a small piece of sandpaper, and a special rubber cement. Here's how to patch an inner tube:

  1. Select a patch appropriate to the size of the hole(s). The patch should overlap by 1/2 inch (1 cm) or more on every side of the hole.
  2. Use the sandpaper provided in the patch kit to buff the surface of the tube for an area a bit larger than the patch. If you don't have sandpaper, you could sand the affected area of the inner tube on clean, dry pavement -- concrete is best. You need to buff the tube so that it is no longer shiny.

    If there is a molding line running along the area where the patch is to be applied, you must sand it down completely, or it will provide an air channel. Jobst Brandt suggests carrying a Bic razor blade in your patch kit to slice off mold lines. [I tried this and cut a hole in the tube -- back to sandpaper. John Allen]

    You could lightly sweep away the sanding dust with the heel of your hand., but avoid touching the buffed area with wet or greasy fingers.

  3. Apply a dab of rubber cement from the patch kit, then spread it into a thin coat, using your cleanest finger.

    Work quickly. You want a thin, smooth coat of cement; if you keep fiddling with it as it begins to dry, you'll risk making it lumpy. The thinner the cement, the faster it will dry.

  4. Allow the cement to dry completely. It will become less shiny as it dries.
  5. Make sure the cement has dried completely! You can check by tapping it with a knuckle.
  6. Peel the foil from the patch and press the patch onto the tube firmly.
  7. Squeeze the patch tightly onto the tube. You're done!
If you follow this procedure, and use good materials, your patched tube should be basically as good as new. (Unless you plan to ride down long mountain grades, using the brakes. If patches get very hot, they can come unglued).

Patch failure generally results from one of two errors:

The video below shows checking of the tube, tire and rim, and patching the tube.

For more technical detail, see Jobst Brandt's comments.

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Re-installing the Tire

Although you usually need tire levers or a similar tool to remove a tire from the rim, usually you should be able to re-install the tire with your bare hands.

If you try to pry the tire on using tools, you are very likely to wind up pinching the inner tube between the tool and the rim, puncturing it.

It is usually helpful to have a little bit of air in the tube: just enough to make it sort of round rather than flat. With Presta-valve tubes, I usually just blow air into the tube by mouth.

It sometimes helps to stretch a brand-new tube first. I do this by stepping into it and lifting away by hand.

Start by fitting the valve of the inner tube through the valve hole. You may need to lift a rubber rim strip up at the valve hole and slip it all the way onto the valve stem so the valve stem doesn't try to drag it into the valve hole. Loosely secure the valve using a valve cap or retaining ring so it won't fall back through the hole. If your valve is threaded for a retaining ring, don't tighten it down very far yet, just thread it on far enough that the valve can't fall out of the rim.

With the tube dangling down along one side of the wheel, install one edge of the tire onto the rim, so that the tube is hanging out of the open side. This is usually pretty easy.

Next, tuck the tube into the tire. It is best to start at the valve, work your way one third of the way around the tire, then go back to the valve and work around in the opposite direction.

Once the tube is in place, you're ready to install the second side of the tire. This is the hardest part of the whole process, and the hardest part of this is the very last segment.

If you start at the valve, it won't be a complicating factor when you are trying to lift the last bit of tire bead over the edge of the rim. With a very narrow rim, you may have to start opposite the valve -- just don't finish right at the valve.

As you install the second side of the tire, try to push it toward the middle of the rim channel, where the channel is deepest. This will give you more slack.

Make sure that the tire bead is not sitting on top of the base of the valve. If it is, push the valve almost back through the rim to raise the reinforced patch at the base of the valve, and push the tire down around it.

For the last few inches of tire bead, some considerable force may be needed to pop it over the edge of the rim. (Some rim/tire combinations are easier than others.) If it is giving you difficulty, resist the urge to press the middle part over. Instead, work alternately from each end of the section you're trying to lift over. Going back and forth from side to side will usually get it.

Most folks do this by holding the wheel horizontally, with the open side up. Wrap your fingers around over the tire to press on the bottom of the rim, while you push the tire either with your thumbs or with the heels of your hands.

If you just can't get it by hand, here are some things to check:

Some tire/rim combinations are just too tight a fit, and you may need to use a tool. The best tool for this is the "Kool Stop bead jack" because this tool lifts the edge of the tire without going inside of it, so it is less likely to damage the inner tube than a conventional tire lever is.

Inflating the Tire

Once the tire is fully installed on the rim, you can inflate it, but it may not be as round as it should be. If it isn't, it is usually because the tire needs to be "seated" so that it sits at the same depth in the rim all the way around.

You are less likely to have a problem seating your tire if you have the wheel off of the ground before you start. If the tire is completely flat and is sitting on the ground with the weight of the bike on it, the part that is at the bottom is likely to seat incorrectly.

Generally, if your bike has quick-release brakes, it's best to inflate the tire before putting the wheel back on the bike. If you don't have quick-release brakes, though, it's easier to install the wheel before pumping up the tire.

It's best to start by inflating the tire just enough that it takes shape, maybe 20-30 PSI, and to check that it is seated properly before full inflation. Check the seating by spinning the wheel and watching the tire.

Once you're sure the tire is properly seated, inflate it to full pressure.

Seating the Tire

If the tire is not seated properly, usually this will take the form of having most of the circumference of the tire in the correct place, but there will be one place where the tire either bulges out too far, or dips inward toward the rim. Note, it could be OK on one side of the tire but not the other.

Most tires have a "witness line" molded into each sidewall. This is a narrow ridge of rubber running around the side of the tire, just outside of the rim. Spinning the wheel and observing the witness line will help you locate the place where the seating might be off.

Seating A Bulging Tire

If one part of the tire bulges out farther than the rest, deflate it right away or it may explode with a loud BANG! Manually re-arrange the tire to get it centered on the rim before re-inflating it. Make sure the tire bead isn't sitting on top of part of the inner tube, or the rim strip. This can happen if the rim strip is too wide, or is installed off-center.

If the bulge is right at the valve, this usually indicates that the tire is sitting on the reinforcing patch at the base of the valve. Completely deflate the tire, and push the valve up into the tire with your thumb, while pressing the tire down around it, then pull the valve back down before inflating.

Seating a Tire that Dips Inward

If your tire dips inward at one spot, without bulging out at another, it is usually a sign of an unusually tight fit. This may make it a bit of a struggle to install the tire, but it also means that you can get away with considerable overinflation with no risk of blowing the tire off the rim. Indeed, the best way to seat a "dipping" tire is by temporarily overinflating it until it "pops" into position. A tire may also dip because a rim strip is raising it slightly, so check the rim strip.

In some cases it may be beneficial to lubricate the side of the tire. This can be done with soapy water, but I usually use spray window cleaner for this, because it doesn't leave a soapy residue on the braking surface of the rim.

A tight fit is safer because it will hold the tire in place if it blows out during a ride. A loose tire will flop around, making the bicycle impossible to balance, and can catch on a rim brake, locking the wheel. If it is the front wheel, this can result in a very sudden and serious crash.

Re-installing the Wheel

Re-installing the wheel is a critical task, and if you don't do it right, the wheel can fall out, leading to a serious crash. This is particularly important on the front wheel. If it falls out you will probably land on your face!

Quick-release Wheels

Hundreds of people suffer gruesome injuries every year as a result of improper use of front-wheel quick releases, but if you understand their operation, they're quite safe and secure.

Twist or Flip?

The quick release handle can move two ways: it can twist around like a wingnut, or it can flip 180 degrees outward and back, like a hinge.

The twisting motion adjusts the operating range of the quick release. You may have to hold onto the cone-shaped nut at the other end of the axle. You can't get the quick release tight enough by turning it.

The hinge-like flipping motion is the locking motion. In the "open" position, the quick release handle curves away from the bike. In the "locked" position, it curves toward the bike. (Very old levers are not curved, though -- but the tight position then is with the lever pointing clockwise at its base.) Never, ever ride with the lever in the open position, or partway closed!

If the quick release is too loose, the flipping motion will be easy, but it will not hold the wheel safely--flip it back, turn the adjusting nut clockwise some more, then try again. The front forks of many newer bicycles have retention tabs to keep the wheel from falling out if the quick release is loose. These require undoing the adjusting nut by several turns before the wheel can be removed. You must screw it back in and readjust it when reintalling the wheel.

If the handle is too hard to flip, and you cannot get it to flip far enough to lie flat, loosen the adjustment by turning the adjusting nut counterclockwise. There is a range of only a small fraction of a turn where the adjustment is correct, so you will probably have to repeat the adjustment.

It should take a good firm push to get the handle to lie flat. You will feel the resistance of the lever decrease for the last little bit before the lever lies flat; then it will come up hard against a stop. The decrease in resistance happens as the cam goes over center -- it actually loosens slightly as it reaches its closed position. Then vibration tends to tighten it rather than loosen it.

It is a good idea to set the quick release so that the handle points toward the rear when it is closed. This reduces the chance of getting it snagged on something. Flip the handle to the loose position, turn the handle and the cone-shaped nut together to align the handle once it has been adjusted -- then retighten.

It is customary for the quick release handle to be on the bicycle's left side, keeping the rear handle out of the way of the derailer.

Nutted or "Bolt-on" Wheels

Bicycles that don't use quick-release hubs normally have axles with nuts and washers that tighten against the fork ends of the bicycle. It is vitally important that these be securely tightened with a wrench.

Internal-gear hubs have tabbed or ridged anti-rotation washers which fit into the dropout slots, to keep the axle from turning. Generally, tabs should face the open ends of the slots. You will also have to reconnect and in some cases readjust the shifter cable.

When reinstalling the wheel, the chain on a non-derailer bicycle must be adjusted for minimum slack, so it won't fall off and doesn't bind. Instructions are here. If there is a brake reaction arm, attach it loosely, adjust the chain, then tighten the reaction arm. See advice here.

Newer derailer-equipped bicycles mostly have "vertical dropouts" for the rear wheel, so the wheel can only go in one spot. No adjustment is required with vertical dropouts.

Check the Brakes!

Make sure to check the brakes after you have re-installed the wheel, especially if you disconnected the cable or used a brake quick release to make it easier to remove the wheel.

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Many flat tires are avoidable, but some are not. Some people seem particularly prone to them. This is often caused by poor road position: people often get an unusual number of flats because they are riding in the gutter instead of the traffic lane.

The main travel lanes of most roads are kept fairly clear of glass and other dangerous debris by passing motor traffic. Cyclists who travel in the normal traffic areas of the roadway benefit from this.

Many cyclists, however, hug the curb out of timidity and an irrational fear of being struck from behind by a motorized vehicle. The area close to the curb is where all of the glass shards, sharp rocks and other junk winds up. If you ride too close to the curb, you greatly increase the risk of tire punctures.

Riding too close to the curb also, paradoxically, increases your risk of being hit by a car! By cowering in the gutter, you reduce your visibility. You also encourage motorists to pass you even when there is insufficient room to do so safely. You also reduce your maneuvering room, and may have nowhere to go if evasive action is required.


Tire pressure is the hardness to which a tire is inflated. This is commonly measured in PSI (pounds per square inch), BAR, or kPa (kiloPascals.)

Tires commonly have a recommended inflation pressure range, or at least a maximum value molded into the sidewall. These values are only very approximate, and experienced cyclists rarely pay much attention to the rated pressure.

A major cause of "snake bite" flats is underinflation. Underinflated tires also have increased rolling resistance, making it harder to pedal.

Less well known is the downside of overinflation; this causes a harsh ride and can also cause poor traction on bumpy surfaces (overinflated tires tend to bounce, and a tire that is airborne, even for a moment, has no traction!)

A correctly inflated tire will have a slight bulge where it is in contact with the road. The correct inflation pressure is determined by the weight load, the tire width, and, to some extent, the riding surface.

For details on optimal tire pressure, see the "Pressure" section of my Tires Article.

Airless tires

Of all the inventions that came out of the bicycle industry, probably none is as important and useful as Dr. Dunlop's pneumatic tire.

Airless tires have been obsolete for over a century, but crackpot "inventors" keep trying to bring them back. They are heavy, slow and give a harsh ride. They are also likely to cause wheel damage, due to their poor cushioning ability. A bump can flatten a pneumatic tire almost all the way to the rim without any damage, and spread the load lengthwise along the rim; foam-type "airless" tires/tubes cannot compress nearly as far, and concentrate the load..

Airless tire schemes have also been used by con artists to gull unsuspecting investors.

Tire Choices

The fastest road tires have a thin tread and sidewalls, in the interest of low rolling resistance. Tires with deeper tread resist flats better. It's your choice to make!

Tire Liners

Aftermarket tire liners, such as the well-known Mr. Tuffy, are not necessary for most cyclists. They make your wheels heavy and sluggish, and, if incorrectly installed, they can actually cause flats!

In some regions, notably the Southwestern U.S., "goat-head" (tribulus terrestris) thorns are so common that such liners, or thornproof tubes, are a desirable option.

Kevlar ®

Kevlar ® is a very strong artificial fiber, used in bullet-proof vests and bicycle tires. Kevlar is used in tires two different ways, for two different purposes:

Thornproof Tubes

Special "thornproof" inner tubes protect against "goat-head" thorns and glass shards. These tubes are very thick on their outer circumference, so that a short thorn (or a small glass shard) may be embedded in the tube without being able to reach in far enough to let the air out.

Thornproof tubes are heavy, and add to rolling resistance, so they are a poor choice for cyclists who don't ride in conditions that require them. See also tire liners.

Tire Savers

Some punctures are caused by glass slivers or thorns gradually working their way through the tire tread. A small, sharp object may be picked up by the tire, then gradually work its way in over the course of several tire revolutions. The pointy thing is driven in like a nail into wood by repeated blows against the pavement. A formerly popular device called a "tire saver" or "flint snatcher" used a loosely-sprung piece of wire (generally made from a bicycle spoke) to brush the tire tread constantly in hope of dislodging glass slivers and the like before they could penetrate all the way to the inner tube.

These are of dubious value in practice, but may be of help in backward areas where throwaway beverage bottles are still legal, and glass slivers are a major problem.

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Pressure Gauges

Pressure gauges come in three types:

Valve Adaptors

Presta-adaptorIf you have Presta valves, it is a good idea to carry a Schrader/Presta adaptor. It is a small thing and easily lost, unless you leave it screwed onto the valve of one of your tires. You can add a Schrader valve cap.


You have 7 possible choices of tools to inflate your tires:


CO2 cartridge inflatorCO2 cartridges are small cylinders of carbon dioxide, originally made for seltzer siphons. With a suitable adaptor, they can be used to inflate bicycle tires. When everything goes well, this is the fastest way to inflate a tire. They're also the lightest and most portable inflation device available, so they're fairly popular among competitive cyclists.

The downsides of CO2 cartridges are that they are expensive and wasteful, and that each cartridge is normally only good for inflating one tire one time. While a few of the cartridge systems do permit controlled release of CO2, most of them are "all or nothing" designs, so you can't use them for topping off a slightly soft tire. If you carry only one cartridge and get two flats on the same ride, you may be in for a long walk. I advise against relying on CO2 cartridges except in competition.


Compressors are a popular alternative, when available. Most gas stations will have a compressor available, either for free or coin operated. While these are convenient, they can also be dangerous. If you use a gas-station compressor, you risk blowing the tire off the rim, so you need to be extra-careful, and use a separate, hand-held pressure gauge, too. The problem with using gas-station compressors for bicycle tires is that the volume of a bicycle tire is so much smaller than that of a car tire, so the bicycle tire inflates too quickly.

Many gas stations have a hose connected directly to the compressor, which is typically set at 120 PSI. You can only avoid overinflating your bicycle tire with this kind of hose by holding the head against the valve for a tiny fraction of a second at a time, then checking with your pressure gauge.

The head on the gas station hose may have a gauge and a handle. These make it somewhat easier to use, because you can press the handle down momentarily to add air to the tire, then check the gauge.

A gas-station compressor may have a head with a crank on it. You turn the crank to set the display to the desired pressure value in PSI. As air flows into the tire a bell rings. Each time the bell rings, the gauge checks to see if the pressure in the tire is more or less than the desired pressure. If it is more, the flow is stopped.

With a small-volume bicycle tire, the difference from one "ding" to the next can be 20 PSI or so. If you set the dial to 100, the air will go "ding...ding...ding..." then there's, say, 99 PSI in the tire. This is under 100, so it'll give it another blast and check again, and your tire could well be close to 120 PSI This assumes that the gauge is accurately calibrated for pressures in this range, which is a big assumption. The bottom line is that you really can't trust these gauges for bicycle tires. Instead, you should use a separate, hand-held gauge.

Floor ("Track") Pumps

The most effective human-powered inflation tool is the "floor" or "track" pump. Floor pumpThis has a long vertical cylinder, with a "T"-shaped handle that you raise and lower with both hands. This type of pump has some sort of footrest to keep the bottom held in place, and a hose that connects to the valve. Floor pumps get most of their action from the user's back, and with an assist from gravity, as the actual pumping occurs on the downstroke.

A floor pump for bicycle use should have a barrel about an inch in diameter; a thicker barrel will make it too hard to pump up a high-pressure tire. The better floor pumps have built-in gauges and holding tanks, so you can see just how much pressure you've got, while you're pumping. This makes them very fast and convenient to use. They also provide a bit of upper-body exercise to balance out all the leg exercise which bicyclists get!

Foot Pumps

An less-common type of pump, similar to a floor pump, also sits on the ground, but is operated by pressing with the foot. These are fast, but mechanically complex due to the extra linkages required. They also tend to be designed more for delivering volume than for pressure, so they don't generally pump up to high enough pressure for narrow road-type tires.

Frame Pumps

frame pump"Frame" pumps are portable pumps designed to be carried on the bicycle's frame. They are typically about as long as one of the frame tubes, and have a spring-loaded handle that holds the pump in place along one of the frame tubes. Older bikes often had two brazed-on "pump pegs" to secure the ends of a frame pump. Many newer bikes have a single peg just below the top tube on the back of the head tube, for a pump running below the top tube.

Frame pumps are the best thing to carry on the bike for emergency, on-the-road use. They take a fair amount of work to get up to full pressure, but it beats walking! They pump fairly easily at first, but they can require a fair amount of strength as the pressure gets high.

Frame Pump Technique

Older frame pumps have a hose that screws onto the tire valve. This works poorly with a Schrader valve because air escapes when the hose is being unscrewed. Newer pumps have a clamp-on head that holds pressure better.

It is possible to cut the spring off a long-type Schrader valve core as shown in the photo below, and to remove the pusher pin from the pump hose. Air pressure will then close the valve as the pump is removed. The seal inside the valve is not as good without the spring: a metal valve cap with a rubber seal should be used. You also then can't inflate a tire with a normal Schrader valve unless you carry two hoses, one with and another without the pusher pin. Is all this worth the trouble so you can use a retro pump? Decide for yourself!

Cutting a Schrader valve core
Cutting a Schrader valve core

As you pump your tire up closer and closer to full inflation, the pump gets harder and harder to push. This is particularly an issue with narrow tires that need to be pumped up to high pressures.

Your arms may not be strong enough by themselves to get such a tire up to adequate pressure. Assuming you're right-handed, it can help to brace your left hand on the pump head. If there's a convenient tree, I'll often lean the pump head against the tree, so my left arm doesn't actually need to do any work. If there's no suitable tree or other solid object handy, or if I'm topping off a tire without removing the wheel from the bike, I'll kneel on my right knee and brace my left wrist against the inside of my left knee.

As I approach full inflation, and the pump gets harder to push full-stroke, I will start each stroke with my right arm free, then brace my right wrist against my chest for the final, hard part of the stroke, and use my back to complete the stroke.

It is very important that any type of pump be pushed all the way to the end of its travel on each stroke, otherwise you're wasting most of your effort. Air only goes into the tire once the pressure in the pump is higher than in the tire. You can feel the transition near the bottom of the pump stroke, when it stops getting harder to push.

Be careful that you do not bend or twist the valve stem when using a frame pump with an integral head. Bracing the pump against a tree, or a rock, can help to hold the valve stem straight, so you don't risk breaking it off or tearing the inner tube. A pump with a hose avoids this problem.

One Is Not Enough

A frame pump is not a substitute for a good floor pump; the well-equipped cyclist will own both. The floor pump is for routine pressure topping off at home, and the frame pump is for fixing flats that occur while you're out's too hard to use for non-emergencies.

Mini Pumps

mini pumpThe most popular type of pump these days is the "mini" pump, a shorter version of a frame pump. A clip may attach a mini pump to water-bottle cage bosses or directly to a frame tube, or the pump may even be pocket-sized. Mini pumps are small and easy to carry, but they take much longer to use than full-sized frame pumps. I generally advise against buying mini pumps unless you have particular issues with theft. Their main advantage is that they are small enough to be carried in a bike bag that you can remove when parking in high-risk locations. They also are lighter than than full-sized frame pumps. Some newer mini pumps engage the pressure chamber on both the push and pull stroke; these are faster than others. Topeak Morph ™ series pumps have some floor-pump features including a footpad and hose.

Tire Levers

Traditional tire levers, a.k.a. "tire irons" came in sets of 3, tire leverswith a rounded business end, and a bent, hooked end for hooking onto a spoke. Newer ones are of fiber-reinforced plastic. I have an assortment of them for different tires. For very tight-fitting tires, you need tire levers with thin ends, able to get underneath tight beads. For less difficult tires, a single tire lever with a rounded, grooved end can be faster. I particularly like the "Quick Stick."

A similar unit, the Crank Brothers "Speed Lever" incorporates a telescoping extension that snaps onto the axle. This works very much like the power tools used in garages for mounting/dismounting automobile tires. This doesn't work too well on very tight tires, but on average tires, it is quite fast and easy to use.

The Kool Stop "bead jack" is an articulated tool for installing really tight tires. It has a comfortable handle and two ends, one of which is on a hinge. The rigid end uses the edge of the rim as a fulcrum, while the hinged end lifts the bead up and over the opposite edge of the rim. This is a very nice tool for dealing with really difficult tires.

Kool Stop Bead Jack

Patch Kits

Patch kits are available in any bike shop. A patch kit is usually a small plastic box containing a few patches, a tube of rubber cement, and a bit of sandpaper or a metal scraper for preparing the tube surface. The metal scraper is not advisable for use on bicycle inner tubes -- it cuts too deep. The best patch kit is the Rema "Tip Top" from Germany.

Make sure to follow the instructions.

Glueless Patches

Glueless (peel & stick) patches are available, and they are slightly more convenient than conventional patches. Unfortunately, they don't have a very good reliability record, and I can't recommend them--you're much better off with a standard patch kit.


Unless your wheels have quick release hubs, you'll need a wrench or two to remove the wheels. (The term "wrench" is not common in British usage, where the the term "spanner" or "key" is generally preferred.)

Wrenches are divided into two families:

Spoke Divider

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