Understanding how to change a flat tire is an important skill to practice. Not only can this skill allow you to finish your ride, but it is also a crucial component to keeping yourself safe while riding.
Depending on how your tire loses air on a ride you’ll use a few different methods to fix the puncture.
First, your decision for how to manage a puncture depends on if you have your tires set up tubeless or if you have a tube in your tires.
If you have a tubeless setup, your tire should have a few ounces of sealant fluid inside it and no tube. It is important to check if you still have wet sealant in your tires every few months.
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In order to check if you have wet sealant, you can remove the valve core from your valve stem, place the valve stem at the bottom of the wheel, and stick a tool like a small allen key in the valve core to see if it comes out dry or wet.
If your tool comes out wet, you likely do not need to add sealant. However, if your tool comes out dry, it is time to add sealant.
Once you know your tires are set up properly, you’ll need to have some specific tools to help you change a flat.
It is important to carry these tools with you on every ride. Many riders prefer a saddle bag or a frame bag where they can permanently keep their tools to ensure they never ride without them.
Recommended tools include a pump, a CO2 cartridge and nozzle, one or two tire levers, a set of plugs, a tube and a patch kit.
While this list may seem intensive, having each of these tools at your disposal will certainly come in handy when changing a flat. Often missing just one of these can make the difference in finishing your ride or walking your bike out to the trailhead.
If you’re riding and you experience a puncture, first move to the side of the trail to inspect your tire. Hop off your bike and listen to where the air is coming from.
Since you should have liquid sealant in your tire, the first step is to move the puncture to the bottom of the tire to help sealant fill the hole. Often, you’ll start to see white sealant start oozing out of the puncture.
Ideally, the sealant will close the puncture and you can continue riding after adding a bit of air to your tire, if needed.
If the sealant is not enough to seal the puncture, you’ll need to start utilizing the tools you brought.
First, we can try to use the plugs. Plugs work to help fill the space of the puncture in order to allow the sealant to finish the job.
There are numerous types of plugs, but each one acts as an additional space filler. You’ll want to identify precisely where the puncture is and use the plug applicator to shove the plug into the tire where the puncture is.
Once you’ve utilized a plug, move the puncture to the bottom of the wheel so the sealant can once again work to seal the puncture. At this point, you may need to add some air to the tire.
Choosing the right inflation tool can be tricky. CO2 cartridges are a one-time use tool that can blast a large volume of air into a tire.
Typically, we can use a pump to inflate a tire and save our CO2 cartridge for another day.
If your plugged puncture is at the bottom of the wheel, begin pumping up the tire to see if the plug and sealant will fill in the hole.
You’ll want to listen closely for any other air leaking out of the tire. If no air is leaking and the plug has held, you can inflate your tire and continue riding!
However, if the air is still leaking, you have two options.
The first option is to try to use the CO2 cartridge to inflate the tire. Sometimes, the blast of air will move enough sealant into the hole to seal it.
Typically though, if a pump will not seal the hole, neither will a CO2 cartridge and it is best to put a tube into your tire in order to finish your ride.
There is one exception to this rule. If you have air leaking out of the sidewalls where the tire seats onto the wheel, using a CO2 cartridge can re-seat the tire on the rim.
Sometimes, when the tire loses pressure from the puncture it will also un-seat from the rim which will cause air leaks in multiple places. If this is the case and your plug has sealed the puncture, you can try to use a CO2 cartridge to re-seat the tire.
All CO2 nozzles are different it is important to learn how yours works so you release the air into the tire successfully.
If the hole in your tire is too large to fill with a plug, it’s time to use a tube. This is the same process you will use if you do not have a tubeless tire setup.
The first step is to remove your wheel and deflate the tire. Unscrew the valve core and hold it down until all the air has leaked out.
Next, you’ll unseat the tire from the rim. One easy way to do this is to squeeze the tire towards the middle so that it pops off of the rim.
Using your tire levers or your hands, pull the tire off of the rim on one side of the tire. There will be some sealant in your tire still which you can leave there for the time being.
At this point, you can look at the inside of the tire where your tire was punctured to remove any sharp objects that may have punctured your tire. You can keep the plug in your tire if you have used one earlier.
Next, remove the valve stem by unscrewing the nut on the outside of the rim and popping the valve stem through the rim. Same this valve stem and each of the seals and nuts for later.
Using your pump or your mouth, add a small amount of air to your tube. Put the valve stem of the tube into the hole in the rim of the wheel and walk your hands around the rim to move the tube into the tire.
Carefully, push the tire back into place inside the rim, making sure no small parts of the tube are puckered into the tire. If any part of the tube is caught, you’ll likely puncture your tube as well.
You may need to use tire levers to pull the tire back onto the rim after you removed it. Using the levers you can squeeze them between the tire and rim, then bend them up towards the tire to pop the tire back into the rim.
Slowly start to pump up your tire, checking for any leaks or parts of the tube outside the tire as you go.
If you’ve been riding tubeless, you may want to add more air to your tire than you were using before. Airing on the cautious side and reinflating with a little too much air is typically better after changing a flat.
At this point, you can put your wheel back on your bike and continue riding.
When you get home, you’ll want to again remove your wheel and take the tube out.
Sometimes you can use a tire with a puncture if it will seal with some additional sealant added and perhaps a bigger floor pump.
If your tire will not seal because the puncture is too big, you may need to replace it or continue riding with a tube.
If you have been riding with a tube instead of a tubeless setup, you have two options for fixing a flat.
The first is to put a new tube in your tire and the second is to use a patch kit.
A patch kit is an easy way to patch a hole in your tube if it is small enough and easy to find in your tube.
When you are looking for a puncture in a tube, it can be helpful to inflate the tube slightly in order to listen or feel for the leaking air. Once you find the hole, deflate the tube and follow the instructions in your patch kit to fix the hole.
While many riders who have a tubeless setup do not use patch kits often, it is possible to get more than one flat in a ride, and having a patch kit can be a saving grace.
If you’ve put a tube in a tire that originally set up tubeless and you get a puncture in that tube, that’s the perfect time to pull out your patch kit.
There are a few other circumstances that require specific tricks for fixing a flat.
One circumstance is if you slice your sidewall and the slice is more than half an inch long. If you are concerned that using a tube will risk the tube emerging from the tire or puncturing easily because it is exposed, there is one fun trick that can save the day.
If you find yourself with a big sidewall puncture and you have a food bar or gel, go ahead and eat it and use the wrapper as a buffer between the tube and the tire. While unconventional, this trick has helped riders out of some sticky situations.
Another specific circumstance is if you do not have plugs but feel a plug is the right tool for the job. Sometimes, it can be possible to use a small bendy stick in the place of a plug.
If you can easily find the leak, shove a small bendy stick in the puncture and this may provide enough filler for the sealant to work.
Flats are inevitable, but if you’re prepared and understand what your tools are for, you’ll be sure to make it back to the trailhead. Good luck out there!
Emily Schaldach is a professional cyclist from Colorado. She grew up racing mountain bikes and competed at the University of Colorado, Boulder where she expanded disciplines to race downhill, road, and cyclocross. Emily is currently on the Firefly Bitchstix Cycling team, also known as Team BitchnGrit, and competes primarily in cyclocross and gravel events.