How to Fix a Flat Tire
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Okay, so now you have a flat. What to do? Check to see if the cause of the flat is obvious. If it’s a puncture flat, there may be something stuck in the tire that needs to be removed; a nail, thorn, piece of glass, etc. If this is the case, try to note where the tire the puncture occurred, to help find the corresponding place on the tube.
If the cause of the flat isn’t obvious, it may be a pinch flat, sometimes called a snakebite flat, which typically leave two small holes in the tube that are close together. This type of flat is caused by hitting something hard like a rock, when your tire is a little soft. The tube gets pinched between the object you hit and the rim, causing the flat. Keep you tires fully pumped up! It’s important!
Next, if the flat on in your rear wheel and you have a bike with a derailleur system, shift the chain onto the largest chain ring in the front, and the smallest sprocket in the rear. This setup is the easiest for getting the wheel on and off.
Since you read the Tire Repair Checklist, you have the tools to make the necessary to repair the flat! 😉
1. Wheel Removal
First, after taking out your tools, squeeze as much air out of the tire as possible.
1a. Releasing the Brake
If you have caliper brakes (where the brake pads press on the rim of the wheel to stop you), there is usually some mechanism to release the brake pads to their widest position. It may be necessary to do this to remove a wheel that doesn’t have a completely flat tire, and to put the wheel back on if you pump up the tire first. Don’t forget to re-tighten your brake mechanism before you begin riding again! Your brake will feel pretty mushy if you forget.
If you have coaster brakes, and you are removing your rear wheel, you will need to unbolt the brake arm from the frame to be able to remove the wheel. Put the bolt somewhere where you won’t lose it, such as back in the hole of the frame, and hand tighten the nut back on the bolt.
1b. Positioning the Bike
Position the bike so you can make the repair. Often the easiest thing to do is to flip the bike upside down, so it’s sitting on the handlebars and seat. If, however, you prefer to lay the bike down on it’s side, and your bike has a derailleur system, be sure to lay it on it’s right side so you don’t damage the derailleur. The derailleur is somewhat fragile from side to side, and you don’t want to get it out of alignment.
1c. Releasing the Wheel
Okay, now that you’ve done the preliminaries, go ahead and release the wheel by flipping the quick release lever, or loosening the wheel nuts, and remove the wheel. If it’s a rear wheel, use your gloves so you don’t get too greasy! Manually remove the chain from the rear sprocket to remove the wheel.
2. Inner Tube Removal
Bicycle tires have a “bead”, which is a wire or cord loop that is molded into the inner edge of the tire on both sides. This helps keep the tire on the rim, as the beads are slightly smaller than the rim of the wheel. To remove the tube, you have to pry one bead on one side of the tire over the rim, then remove the tube from the tire.
2a. Freeing the Tire Bead
To begin, press one side of the tire into the center of the rim working your way all the way around the wheel. This is to be sure the tire isn’t stuck to the rim. Then repeat the process on the other side of the rim. Now, sometimes the tire is loose enough that you can roll it off the rim without using any tire irons. On lightweight road bikes this isn’t usually the case, but it’s worth a try. More than likely, you’ll need to use tire irons to remove the tire.
2b. Using Tire Irons
Use the rounded end of one of the irons to pry the tire bead over the rim near the valve stem. Use the slot in the iron to hook it onto the nearest spoke. Repeat the process one spoke away from the first iron using the second iron to again pry the bead over the rim. Then repeat the process again with the third iron, again one spoke further away. Using the same technique, again use middle iron to pry the bead over the rim a little further around. Now use the middle iron to go along the edge of the rim and pull out the rest of bead.
Note: Don’t pull off the other side of the tire! Just leave it on the wheel, and remove the inner tube.
3. Locating the Hole(s)
(or replacing the tube if it can’t be patched)
First determine the type of flat you have, and where. If you kept track where the puncture is on the tire, you can skip this step: With the tube removed, pump a little air into it, until you hear a hissing sound. Hint: If you’re having trouble locating where it’s coming from, hold the tube near your face, and you can feel where the air is coming from.
4. Patching the Hole<(s)/h3>
Once you’ve located the hole, determine how big it is. If it’s a small puncture, or snakebite, it’s pretty easy to patch.
Rough the area around the hole with the pad of sandpaper in the patch kit to an area a little larger than the size of the patch, sanding down any “mold lines” (raised lines) that may be in the patch area. This exposes raw rubber for the patch glue to adhere to. Don’t skip this step! It’s important, and don’t touch the freshly sanded area with dirty or wet fingers!
Remove the backing from the pre-glued patch (or put glue on the tube over the area you cleaned and spread it into a thin layer with your finger). If you are using glue, let the glue dry and then press the patch firmly onto the tube. I like to continue pressing the patch on for about a minute. Be sure the edges of the patch are glued down.
5. Inspecting the Tire
Now check to see what happened, if you don’t already know. If you don’t see the problem visually, and it’s a puncture and not a snakebite, very carefully run your finger around the inside of the tube. Be careful, if it’s a glass shard, or piece of metal you could cut yourself. If the puncture is on the inside of the tube where it’s next to the rim, it could be coming from either (a) a burr on the rim, or (b) a spoke end protruding through the protective tape that runs in the base of the rim. If you find a spot where the tape is torn or misaligned, try to correct it. In a pinch, try to place a patch still in it’s package over the area, or something similar.
If the repair is for a snakebite puncture, there probably won’t be any problem found with the tire or rim; it’s usually caused by hitting a rock, concrete driveway edge, or some other hard object with too little tire pressure. The tube is deformed by the object, and gets pinched between the object and the rim, making the two little holes.
6. Reinstalling the Tube
With the tube repaired (or replaced) and the tire and rim free from defect, put a little air in the tube so it fills the tire when you put it back in; be sure to line up the valve stem with it’s hole in the rim. Push the valve stem all the way into it’s hole, and work the bead back over the edge of the rim by the valve stem with your hands. Repeat this process again about 6 inches away, while holding the first spot in place.
7. Pushing the Bead Back Onto the Rim
Be sure the bead isn’t on directly on top of the valve stem; if it is, push the stem into the tire a little. Now do the same thing about 6 inches from the first spot, in the other direction. Keep repeating this procedure, as long as the remaining bead can be pushed on by hand. If it’s really tight, you may have to use a tire iron to get the last little bit of the bead on. Be very careful not to pinch the tube with the tire iron!
8. Replacing the Wheel
Hard part is over! Go ahead and pump up the tire to riding pressure. Be sure to pump it up enough! It would be a real bummer to resume your ride and get a snakebite!! Replace the wheel in the reverse order of removing the wheel. One thing to watch out for: when tightening the tire, be sure it is centered in the frame at the top of the wheel. Otherwise, when you re-tighten the brake pads, the wheel may rub on one pad or the other. Also, Warning!! Be sure the wheel axle is completely properly seated in the dropout of the frame, or fork. The wheel could come off and cause a serious accident otherwise!