How to Fix a Bike Flat
The open road, miles away from home (and cell coverage), is no place to discover that you don’t know how to repair a flat tire.
Let me be honest. I am considered not-so-bright in the realm of doing things without serious trial and error, and this category includes making bike repairs. But I am committed to making progress, however slowly. To that end, I have taken a bike mechanic class in which I replaced a tube on my road bike, which theoretically gives me the know-how to fix a flat.
Since then, I have struggled and then triumphed with fixing a flattened tire. Yay! As a result, my knowledge of wacky things that can go wrong is relatively high. Here are the basic instructions as well as what might go wrong during the process.
How to Fix a Bike Flat
1. You'll need to carry these items with you:
- Tire levers (2), also known as tools
- Pump (tire inflator and CO2 cartridges or small hand pump)
- Optional (more items are shown below; these may be helpful to those who know how to use them)
2. Remove the wheel.
- Change gears so that the chain rests on the gear closest to the outside of the bike.
- Release the brake mechanism (I've noticed that some brakes have quick release mechanisms and some require maneuvering).
- Take off the wheel by using the quick release mechanism (if you don't have a quick release, loosen the bolts that hold the wheel in place; and you'll need special tools for this step).
- Have someone hold the bike while you fix the flat or flip the bike so that the seat is on the ground.
3. Check the outside tire.
- Make sure that there are no obvious problems with the tire tread like a nail stuck in the tire.
4. Remove the tube inside of the tire.
- Using the tire lever, lift the lip of the tire over the rim on one side (note: many bike mechanics like to remove the entire tire; however, my cyclist friends recommend removing one side of the tire only in order to make a quick fix when on a ride).
- Move the tire lever a few inches along the rim and use the lever to hold the tire in place over the rim.
- Take the second tire lever and continue lifting the tire over the rim until an entire side of a tire is off the rim.
- Remove the cap on the tube valve, let out any remaining air, and then remove the entire tube. (My tubes have always been completely flat but some may have contain some air.)
- Run your fingers along the inside of the tire to check for any sharp items that may have punctured the flattened tube and may cause problems with the replacement tube.
5. Replace the tube.
- Give the replacement tube some shape by blowing air or pumping a small amount of air into the tube.
- Position the tube valve in the rim.
- Push the tube inside the tire.
- Put the tire back inside the wheel (both sides) by pressing the beaded part of the tire under the rim, move along all sides of the rim until the entire tire is snug. The last part of this process can be tricky so you may need to apply extra pressure and finesse to getting the last few inches of the tire under the rim.
- Inflate the tube to the right pressure.
6. Replace the wheel.
- Place the wheel so that the chain engages with the sprocket on the wheel.
- Re-engage the brake.
- Check to make sure the wheel is firmly attached.
When you get home, discard the old tube and put a new tube in your bike bag. If you used a C02 inflator, put another cartridge in your bag.
To see how a bike mechanic changes a flat tire, see this video:
What Can Go Wrong
If it's not working, here are some reasons why.
- You have a tube but it’s the wrong size. Identical-looking bikes may require different sizes. Problem solved: Ask your bike shop to sell you the right size of tube. And, check the dimensions printed on the flattened tube before you begin installing a new one.
- You only have one tire lever, and you need two. Problem solved: Levers are cheap so get at least a couple, maybe more to have around. If you are on the road or out on the trail, don’t despair: use nimble fingers or borrow a friend’s tool.
- Your bike pump doesn’t work properly; or, in my case, you have difficulty in using the pump properly. Problem solved: Practice inflating your tires using your pumps: a large one that you keep in your house or car and a small one that you carry on your bike (either a small hand pump or a CO2 inflator).
- In your rush to begin repairing the flat, you forgot to move the chain to the outside position by changing the gears (applicable to your rear tire). Problem solved: Be patient and remember that you have to replace the wheel at some point. But if you forget to change gears, then don’t worry; just be extra diligent when putting the wheel back on and take a test ride.
- The tire won’t settle back into the wheel. Problem solved: If you’re having trouble getting the tire tucked in after replacing the tube, start over. Take out the tube. Put one side of the tire back in the rim. Replace the tube (again) and push the tube into the tire cavity, not next to the wheel. Then put the other side of the tire back in the rim.
How to Avoid a Flat
Of course it's best to avoid the flat altogether. Here are some tips to prevent a flat.
- Before riding, pump your tires to the correct PSI (pressure per square inch), which is printed as a number range on your tire. If you have questions, ask your bike mechanic to recommend a precise PSI setting.
- Match bike tires with surface conditions.
- While riding, avoid hazards such as loose gravel and potholes that can cause flats or damage to your bike.
Do you have tips on avoiding or quickly fixing flat tires?