Getting a flat bike tire is one of those things that isn’t a matter of if, it’s a matter of when. If you’ve been lucky enough to avoid getting a flat tire, then you might think you don’t need to learn how to fix a flat. If you’ve had one before, and a friend or passerby has helped you out, consider yourself lucky and do the right thing by passing the favor along to someone else. Learning how to fix a flat bike tire is an essential skill that can be done correctly—you finish your ride and never think twice—or it can be done incorrectly, causing either another flat or a loss of control. We’re only going to go over learning how to fix a flat with a clincher tire, as tubeless and tubular tires are pretty different. Not sure what you’ve got? Then there’s a good chance you’ve got a clincher setup, as it’s the most common.
Before we break down the steps that’ll help you learn how to fix a flat, a few tips before you get started.
It doesn’t matter if you’re the most experienced mechanic in the world—if you don’t have the supplies you need to fix a flat tire out on the road while you’re riding, it won’t matter. Sure bringing a patch kit is a good last resort, but every triathlete should have a spare tube (WITH A VALVE STEM LONG ENOUGH FOR YOUR WHEELS! I can’t stress this enough), either a portable pump or a couple of CO2 cartridges and a valve head, and three good tire levers. If you get the flat, the first thing you do after fixing it when you get home is replenish your kit.
Learn How To Fix A Bike Flat At Home
Out on the side of a busy road is not the place to be reading this article and putting it into practice for the first time. You’ll be sweaty, dirty, frustrated, late for something, and possibly in a dangerous spot. Go through the steps below at home, at least once, with a tube that hasn’t gone flat. Don’t just pull out a good tube and put it back in; pull out the good tube, take out a brand new one, and do the steps below with the brand new tube. Trust me, it’s different.
Let’s do this!
How to Fix a Flat Bike Tire
Step 1: Find A Safe Place To Work
If you think you’re invisible to drivers while riding, imagine how hard it is to see you when you’re crouched over in a strange place. Get yourself entirely off the road, if possible, and leave your helmet on. You just never know.
Step 2: Remove The Wheel
First, open your brake calipers. If it’s the front wheel, undo your skewer (remember righty tighty, lefty loosey); if it’s the rear wheel, hold the seat, lift the rear wheel off the ground while still attached, and shift your rear gears into the smallest-toothed cog (the hardest one). Then loosen the skewer, push the wheel down or back—depending on the direction of the dropout openings—and loop the chain off the cassette and around the skewer. Place the bike on the ground, drive side up.
Step 3: Inspect The Outside of The Tire For Obvious Foreign Objects
If you can see or feel anything sticking out of your tire, now is a good time to pull it out. Be sure to take note of where you removed it on the wheel, so you can check that same spot inside the tire—just in case you didn’t get it all.
Step 4: Deflate The Tire Completely
If it’s a presta valve stem (the pointy kind), loosen the top and press down. If it’s a schrader valve stem (the kind you see on cars), use your tire lever to push inside the valve. Either way, while the valve is open, press the tire to remove as much air as you can.
Step 5: Unseat The Tire From The Rim
This can be a little tricky depending on your tire/rim combo: Holding the tire with one hand, use your thumb to push the tire off the rim—both upwards and off the side. With some rim/tire setups, you’ll be able to use two thumbs to push the tire and tube completely off and over the side of the rim; with most, you’ll need to slip a tire lever under the small gap between tire/tube and rim.
Step 6: Remove The Tire From The Rim
Either using your thumbs or the tire lever (or two), fold the tire/tube off and over the side of the rim in one spot, then either use your hands to continue moving it off the rim along the entire wheel or slide the lever across the length of the wheel, unseating one side of the tire/tube as you go. It’s not essential to remove both sides of the tire if you can get one side off and remove the tube. Just be sure you can do a thorough job of the step below.
Step 7: Inspect The Inside Of The Tire (IMPORTANT STEP!)
Take out the tube slowly, and see if you can find a hole as you go. If you find a hole, look at that corresponding spot in the tire (hence why we shouldn’t just rip it off in a fit of rage!). If you don’t, visually inspect the inside of the tire casing for any debris, no matter how small. You’d be surprised how little can create a hole in a fragile tube. If you still find nothing, very carefully and slowly run your finger along the inside of the tire. Be super careful here, as you’re looking for something sharp, so it can easily cut you. A gloved finger is best here, but work with what you’ve got. Remove anything you find, and know that nine out of 10 times, there is something that caused the flat lodged either in the tire or the tube. If you don’t remove it, you’ll get another flat almost immediately and have to go through the whole process again. You don’t want that, particularly if you don’t have another tube.
Step 8: Prepare Your Replacement Tube
Remove your spare tube from it’s home, unscrew the valve (presta), and allow air to enter it by pressing down on the valve one way or another—depending on its type. In the best case scenario, a pump or two from a hand pump should put in just enough air to give the tube some shape. If you’ve got CO2 and a presta valve, push in the valve, hold the stem with your fingers, and blow as much air into it as you can to help “de-flatten” your previously packed spare tube. This is actually pretty important. Once you’ve got some air to give the tube shape, close the valve back up so air can’t escape.
Step 9: Put One Side Of The Tire Back On The Rim
Assuming you’ve taken the tire completely off the rim (skip this if you still have one side of the tire on the rim), hook one side of the tire onto the rim, leaving the other side hanging off. This shouldn’t be particularly hard or require the use of a tire lever. If it’s really tough, make sure the tire isn’t mounted on both sides already somewhere else on the wheel.
Step 10: Pack The Tube Into The Tire
Start putting your VERY LIGHTLY inflated tube all along the inside of the half-mounted tire, putting the valve stem in first (you may need to pull back the tire to do this), and working along the whole tire. The tube should be as far as possible toward the part of the tire that contacts the road when you’re riding in a straight line—away from the rim.
Step 11: Begin To Reseat The Tire On The Rim
This can be very tricky based on your tire/rim combo. Starting just to the side of your valve stem, use your hands to seat the tire bead that’s loose onto the inside of the rim. Move away from the valve as you go, ending back on the other side of the valve—this’ll be the last section you seat. As you go, try to tuck the tube as deep into the tire as you can, and no matter what don’t let the tube get caught between the tire and the rim. If this happens, remove that section and try again. Think of tuck, then roll the tire, and seat the tire on the rim. The farther the tube from the rim inside the tire, the better.
Step 12: Finish Reseating The Tire On The Rim
This is where things can get really tough. As you get closer to where you began reseating the tire on the rim (the valve stem area), the tire will get tighter and tighter. At some point, you may need to start using a lever. Remember to keep the tube away from the rim at all costs, and never pinch the tube between the lever and the rim—you’ll immediately flatten the tube. Really focus on “tucking” that tube deep inside the tire as you go. When you get close to the valve (where you began), push the valve up, so the tube pushes against the inside of the tire away from the rim. If you need to use a tire lever (or two) to reseat the tire on the rim and “close” the tire, just be careful you don’t pinch that fragile tube. Using the valve to keep it clear and far away from the rim should help. If it’s really tight at the end, use two tire levers, one on either end of the “open” section, and flip the tire onto the rim—again, stay clear of that tube!
Step 13: Check The New Tire/Tube
This is so important, it’s got its own step. Be sure there is none of the tube sticking out from underneath the tire. If you see some, you’ve got to find a way to “tuck” it back in—even if that means unseating the tire and packing the tube back in. Lightly inflating the tube should help here, but if the tube is caught between the rim and tire, you’ll could get an immediate flat when you reinflate.
Step 14: Reinflate The Tire
First, be sure you reopen the valve (remember, you closed it earlier to keep air in the tube and give it some shape). Once open, press the valve down so it unsticks and lets air in and out. If you have a CO2 cartridge, follow the instructions that came with the inflation chuck, but either way rotate the wheel so the valve is at 12 o’clock. If you’ve got CO2 that can stop and start without exhausting the cartridge, inflate the tire halfway, inspect the tire/rim area to make sure the tube isn’t caught, then inflate fully. If you hear a loud, dull pang, that could be the tube/tire reseating, so don’t freak out. If you’ve got a hand pump, inflate halfway to the recommended PSI, stop, and check the same thing. If it’s all good, finish inflating to the recommended PSI.
Step 15: Replace The Wheel
If you had to open your brake calipers to remove the wheel, be sure to close them back up after putting it back on. Be sure your skewers are tight, and be sure your wheel is aligned correctly. If it was your rear wheel, pick the rear up by the seat and shift into a bigger (easier) gear.
Step 16: Ride Carefully!
For the first 15 minutes after fixing a flat, be sure not to go too fast or ride too aggressively. Very often it’s hard to find the culprit of a flat, and it’s possible that the tube could go again—even if you’re super careful and a seasoned vet at changing tires. Keep an eye on your tire hardness as you ride, and be careful as you finish your workout!