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There is no bigger buzzkill than a sudden loss of tire pressure during a ride. Learning to remedy a flat tire on your own is absolutely the most important skill that every rider must learn in order to keep riding fun and safe. Here is everything you need to know to be prepared and confident when this situation inevitably deflates your pneumatic fun.
How Tires Hold (or don’t hold) Air
Your tire holds air pressure by either an inner tube or a sealed tubeless system. (I will cover tubeless specifics at the end of this article.) When something causes that system to rupture, the tire will lose air pressure, sometimes at an imperceptibly slow rate, or in a sudden, violent BLAM!
Continuing a ride on a flat or low-pressure tire is nearly impossible, and inadvisable as it will damage your rim. Fixing it on the fly is the only option that does not involve the indignity of walking home or calling a friend for a ride.
Preventing Flats
Give yourself a fighting chance at avoiding flat tires by preventing some of the leading causes:
Low Tire Pressure
Tubes are more susceptible to pinch-flats or “snake bikes” (see below) when under-inflated. A combination of your weight, the tire’s size, and the terrain you are riding will determine your ideal tire pressure.
In general, bigger tires and rougher terrain will require less pressure for the sake of traction, while harder surfaces and smaller tires require more pressure to favor faster rolling. For example, a 23mm road tire on smooth pavement should be pumped to around 100 psi (6.9 bar), while a fat bike being ridden in the snow will work best under 10 psi (0.7 bar).
Rim Strip
The outside of your rim where the tire sits should be lined with a sturdy bicycle-specific strip that covers all spoke ends and holes, as these irregularities can be sharp enough to bust a tube under pressure.
Tip: Gorilla brand tape sold in 1” wide “handy rolls” and works well as a rim tape, if you can’t get to a bike shop for rim tape.
Debris in Tire
Check the tire for embedded bits of glass, wire, or sharp rocks. If you have previously installed a tire, dirt might have been caught between the tire and tube.
Damaged/ Worn Tire
Tires that are worn thin or have slices or holes in the sidewall will not hold a tube for long, if at all.
Necessary Tools
Maintaining and repairing flat tires requires that you have the following tools at your disposal:
Floor pump – tall, T-handled pump used for at-home repairs and pressure top-offs. They are fast and efficient for pumping air, nearly always work with presta and schrader valves, and usually feature a gauge to monitor the amount of pressure in your tire. An air compressor works too.
Tire gauge – I have found that the tire gauge on most floor pumps is not accurate enough for my liking. Accurate tire pressure makes a huge difference in how your bike handles. A digital or dial gauge does the job for consistent results. Find a pressure that works for you and check it before every ride.
Portable inflation – a small, portable pump to fill your tires mid-ride when disaster strikes. Can include a mini-pump, frame pump, or CO2 inflator.
Note: CO2 inflators are a quick way to get a bike up and running, but the gas in the canister will leak out fast than regular air. Be sure to top off your tire after a ride when you used a CO2.
Tire levers – blunt prying tool for removing tires. Some tires can be easily removed by hand and some tight tires will require up to three levers at once. (Don’t use a screwdriver or other sharp object on your tires!). Some multi-tools come equipped with tire levers, making it simple to always have them on hand.
Patches, plugs, boots – various methods to mend a damaged tire or tube. Each style of bike and tire might require different combinations of tools. Any bicycle shop should have basic patch kits with glue and patches, boots, and tubeless tire plugs available.
Types of Flats
Contrary to your experience, there are no bicycle-hating gremlins sabotaging your bike. Flat tires always occur for a specific physical reason, so the first step to resolving a flat tire situation is to put on your diagnostician hat and figure out what caused your tire to lose pressure.
Puncture – This the is most common type of flat you’ll experience and there is little you can do to prevent it. A thorn, bit of glass or some other sharp piece of road debris infiltrates the layers of your tire and assassinates your tube. You will need to find the offending sharp bit by carefully running your fingers around the inside of the tire, taking care to not slice your fingers in the process. Tough tires and thick tubes can help, but the best course of action is to be prepared to patch it.
Pinch – Your rim hit the ground hard enough to damage the tube, usually leaving two parallel “snake bite” punctures in the tube. Sufficient tire pressure can help to prevent this, but sometimes it’s not enough. You might be able to patch this with a large patch, but replacement of the tube is preferred due to the large affected area.
Blow-out – a rupture in your tire or a hole in your rim has allowed the tube to burst out, leaving a slice or star-shaped hole in the tube. This would be difficult, but not impossible to patch. You will also need to repair the tire with a “boot” or cover the hole in the rim that allowed this to happen.
Blow-off – the tire slipped off the rim, allowing the tube to blow out between the rim and tire bead. This will usually appear as a long slit in the tube that will be nearly impossible to repair without replacing the tube.
How to Change a Flat Bike Tire
- Remove the wheel – Because axles and brakes will vary widely from one bike to another, you’ll need to be sure you can comfortably disengage the brake (if necessary) and remove/ reinstall your wheel on your particular bike.
- Remove the tire – This is where tire levers come in. Completely deflate the tire if it’s still holding air and wedge a tire lever between the rim and the tire bead; where the rubber meets the metal.
- Pivot the lever down over the edge of the rim, toward the center of the wheel. If you have a loose-fitting tire, you can slide the lever around the rim and pop the tire right off. If your tire is too tight-fitting for that, use two levers spaced a few inches apart and push them down simultaneously.
- Slide the lever(s) around the circumference of the rim until one side of the tire is completely off. If the valve of the tube has a ring threaded onto it, simply unthread the ring with your fingertips. Pull the tube out for inspection and carefully probe the inside of the tire for embedded objects.
- Pump up the exposed tube so it’s inflated enough to plump up. Look, listen, and feel for air escaping from the tube. Now you know where the hole is on both the tube and the tire, what kind of flat you have (see taxonomy of flats above), and how to proceed!
- If you don’t have the time or tools to repair the tube, stow the damaged tube and pull out your spare tube.
- Partially inflate the new or repaired tube with your mouth (for presta valves, kinda gross, but it works) or your pump so it has a round shape. This is easier than dealing with a flacid ribbon of a tube.
- Reinstalling the tire – once everything is buttoned up, you can start by fitting one side of the tire onto the rim, if you removed it completely in the first place. Be sure to orient the tire your preferred direction if the tread direction matters. Line up a logo on the tire with the valve hole, as this will look “pro” when you’re done and help you locate an embedded puncture object in the future.
- Now comes the tricky part: fit one segment of the second tire bead onto the rim and push the tire onto the rim, working in opposite directions toward the other end of the wheel with your thumbs.It will likely become more difficult as you progress. Keep pressing with your thumbs, allowing no part of the tire bead to escape the inside of the rim.
- If you have a loose-fitting tire/ rim combo, this will be a breeze. If it becomes extremely difficult, hunker down and give that tire the business! Resist the urge to pry the tire on with a tire lever, as that will likely puncture tube, sending you back to the beginning.
- If you have reached the end of what effort you can bear to pushing the last few inches of tire back onto the rim, switch to using your fingertips. If that does not work, reach to the other end of the tire and push the already-fitted tire bead up into the center of the rim channel and work your fingers back up the the unfitted bit of bead. You’ll gain some precious millimeters this way and lit the last bit of tire bead onto the rim without resorting to using tools.
- If all else fails, carefully use the tip of your tire lever to wedge the tire back onto the rim. Do so care to not pinch the tube!
Tire Reinflation Considerations
Start slowly when re-inflating a tube. It is possible that the tube will get caught between the rim and the tire bead, which will lead to a blow-out.
After you’ve gotten a few pumps of air into the tube, check the tire/rim interface on both sides, all the way around the wheel, checking for aberrations – spots where the tube might start to bulge out. If you see one, stop! Deflate tube and it work it back into the tire and reinflate. Repeat as needed until the tube inflates such that the tire is even and centered on the rim.
A loose-fitting tire can be just as troublesome as a tight one. As you start to pump, watch that the tire stays centered on the rim. If it looks uneven or the tire bead start to come off the rim, deflate immediately and push the tire back onto the rim and start again.
How to Repair a Tube
Simply replacing a tube is often necessary, but can be wasteful, expensive, and might not be an option in the middle of a ride. Repair your tubes, if possible, with a patch.
Patch – If you have a small hole in the tube, or at least a hole smaller than your largest patch, you can proceed with patching. Locate the center of the hole and buff an area slightly larger than the hole with the “roughing tool” that came in the form of a square of sandpaper or a metal scratchy pad in the patch kit. This will help the glue adhere to the tube.
Pop open the tube of glue and smear a thin layer of it around the hole.
Here’s where most people get patches wrong: you have to let the glue dry for two to five minutes. Peel the foil backing off a patch after the glue has dried and press it on the area firmly. You’ll probably get glue on your fingers. That’s OK. press the patch over the hole and hold it there for another minute or two before stuffing the tube back in the tire.
Boot – If the tire casing has a slice or hole, putting a new tube in there is not going to be enough, as the new tube is just going to blast out of the hole again in short order. You can “boot” the inside of the tire with a bona fide bicycle tire boot found at a bike shop, or improvise one with a protein bar wrapper, a folded dollar bill, or whatever else you can find that has enough strength and density to keep the tube from rupturing out of the tire again. If a tire is damaged badly enough to require a boot, it’s probably time to replace the tire, so consider a boot to be a temporary fix to get you home.
Tubeless Tire Considerations
Tubeless tires are all but ubiquitous on mountain bikes these days, and approaching domination on most other bicycle phyla. While many of the same concepts apply to tubeless tires, and will apply in an emergency, the following additions must be made:
Risky business – it is possible to use tires and rims that were not designed to be tubeless in a tubeless configuration, but it is generally not advisable. Just because the bead on a tire seals in the shop does not mean it’s going to stay that way under riding conditions. Having a tire blow right off the rim during a ride is a risk not worth taking. If the rim you are using was not designed for tubeless applications, there are rim strips made specifically for this conversion that offer the best compromise. Research and test your tubeless kludge carefully before riding.
Tape it up right the first time – badly taped rims can allow air to escape through the rim. Use a tubeless-specific tape that is wide enough to fully seal the inside of the rim.
When you install new tape, install the tire dry, with a tube, and let the tire sit for several hours, allowing the tube to really mash the tape adhesive down onto the rim. Cut a clean, round valve hole in the tape by melting a hot screwdriver into the tape. (I heat mine over a gas stove before easing it through the tape.) Crank the valve down to really tight to create a solid seal between the valve and tape, which is a common source of leakage.
Reliable setup – When setting up a tubeless wheel, avoid combinations that require heroic efforts involving straps and long sessions with an air compressor to work at all. I have found that tire and rim combinations that can be pumped up using a floor pump or a quick burst of compressed air fit tighter and are less likely to burp air under stress.
Opening the airway – If you can’t get enough air into a tubeless tire to make the bead pop onto the rim, try removing the valve core to open up the flow. Some four-sided spoke wrenches have one opening large enough to grip the flats on a tubeless valve stem core to remove it. Blast air into the tire until you hear the last pop of the tire on the rim shelf, then reinstall the core and re-inflate. You will lose most of the air when you pull the pump off of the core-less valve, but once you have the tire bead secured onto the rim, it does not matter.
Soap it up – the seal between the tire bead and the rim should be a tight fit and might require a little lubrication to make it slide into place. Some mechanics will use some fresh, wet sealant and a lube, but most will use some dish soap and water. You can get a small bucket of the soapy mix and bush it on your tire before inflation. Then use the soapy water to clean your bike while you’re at it. Bonus hack- fill a small spray bottle with tap water and a drop of dish soap. Spray it on your tire near the rim before inflating.
Top off your sealant – the fluidity of tubeless sealant will vary with brand, humidity, tire condition, and the quality of the seal you achieved between your tire and rim. If you can take your wheel off your bike, shake your wheel around and NOT hear liquid sealant sloshing around, you probably need to add more sealant. Check it every few rides, as sealant usually does not last more than a few months before drying out or being used up in plugging holes.
Carry a spare tube – tubeless is great, until it’s not. Then it’s a liability. Any tubeless system can be retrofitted with a tube when you can’t get a tire to seal up.
Learn how to patch a tubeless tire – common wisdom states that a tire that has been sliced beyond what sealant can plug up is as good as dead, but you can prolong the life of a slashed tubeless tire by:
- Plugs – just like a car tire, you can shove a bicycle-specific plug into the tire damage area to make the hole effectively smaller, and therefore, more likely to seal up.
- Patches – you can glue a patch to the inside of a damaged tire in a pinch, by the same method you would patch a tube. A radial patch, like that used to repair car tires, works even better.
- Sewing – a sewing needle and tough thread, like dental floss, can be used to hold a sliced tire together. This solution is often a temporary one, and is best reserved for sidewall cuts rather than tread cuts.
Ask the Bike Mechanic (just be sure to drop off a six pack)
Can I repair a damaged tire or tube, or should I just throw them away?
Sometimes. Tubes can be patched, tires can be sewn or booted. Tubeless tires can be plugged or patched.
Can I use a non-tubeless tire and rim as a tubeless setup?
Probably not. Some can be converted but these conversions are usually not as safe and reliable as a dedicated tubeless system.
Can I put a tube in my tubeless tire?
Absolutely! Most tubeless riders carry a spare tube to use in a pinch if the tubeless system fails, which will happen rarely if the system is set up well. Just remove the tire, remove and pocket the valve, and install the tube like normal.
How much pressure should I pump into a bike tire?
Tire Pressure depends on the size of the tire, the rider’s weight, and the terrain.
High pressure Low pressure
Hard, smooth terrain soft, rough terrain
Narrow, slick tire fat knobby tires
Lightweight rider heavy rider
Consult with the rim and tire manufacturer for high-pressure limits and check with riders on similar bikes and terrain for low limits.
What tools do I need to fix a flat?
Tire levers (usually plastic), tire inflator (floor pump, mini pump, CO2 inflator, or air compressor), sturdy fingers. Never use a screwdriver to remove a tire.
Do I need an air compressor to install a tubeless tire?
Getting a tubeless tire to seal up on the rim can be difficult, and an air compressor helps. Try it with a floor pump first, employing soapy water and removing the valve core if needed. Many manufacturers are now making “tubeless” floor pumps that allow you to charge them up with a high-pressure burst of air to seat a tubeless tire, a wise purchase if you’ve gone tubeless.
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