|There’s nothing difficult about fixing a flat tire on your bike. Yet many riders, especially in urban areas, turn over this simple repair to a bike shop. Print out this page — and gain a new level of biking independence.
|The best way to learn to fix a flat tire on your bike is by doing it with verbal assistance from someone with experience. But it’s a simple process, and can be learned by anyone who spends time on a bicycle simply by doing it.Because we’ve tried to explain each step in detail, taking into account variations that may occur, the process as described below may seem long. After you’ve done it a few times, you’ll change a flat tire almost as fast as you can read this description. Ask our guide to arrange a group lesson some evening if you’re interested.Practice before your next ride, if you can. Or just print out these instructions and take them with you, along with tire irons (usually made of plastic), a pump, and a spare tube or patch kit.
1. Prep the bike.Disconnect the brake; the brake pads may prevent the tire (when it’s inflated) from passing through. Squeeze the brake pads together, then slip out the wire that has a knob at the end, so that the brakes can open fully. (If it’s difficult to get the brake wire disconnected, you can skip this step. In that case, you may need to empty air from the tire before you re-mount it, if the inflated tube is too fat to go through the brakes.)It’s easiest to change a flat when the bike is upside down, or with someone holding it up.If your flat is on the back tire, also put the chain on the smallest gears, both front and back, to reduce tension on the chain. (Remember that you should only change gears while pedaling. In this situation, you can shift one gear at a time, raise the back tire and rotate the pedals forward until the change moves over, and continue, gear by gear, till you’re done.)
2. Remove the tire. Open the quick release lever. (If your bike doesn’t have quick-release tires, you’ll need a wrench to turn the nuts that hold it in place.) If necessary, also loosen the thumb nut on the other side from the quick release, so the wheel will come off. Front tires come off easily.Back tires are slightly trickier, but there’s no need to get your hands greasy. Note the two small gears in the derailleur that the chain passes through. Push the one that’s toward the back of the bike towards the front, and the other one toward the back, so that they roughly form a line from the wheel hub. (You’ll be making the chain follow a straight line, rather than an “S” shape.) Before removing the back tire, mentally note how it sits in relationship to the back derailleur gears. Now lift the wheel out. (If you were not able to turn the bike upside-down, do not rest it on the bare derailleur; lay in on its left side.)
3. Remove the tire from the rim. Start opposite the valve. Slip the cupped end of one tire iron between the metal rim and the tire. Catch the lip of the tire, then lever down, pulling the tire out of the rim. Try not to pinch the tube inside as you do this (easier said than done, since you can’t see what’s happening inside.) Hold this tire iron in place by hand, or use the hook at the other end to attach it to a spoke. Now repeat the process about two spokes over to the right, and again two spokes to the left. This should loosen the tire enough that you can remove it by hand. Make a note of which part of the tire was at the valve, before removing it entirely, to help you find the source of the problem..
4. Look for the source of the problem. Run a finger all through the inside of the tire, trying to find what caused the leak. Often you won’t find anything, but if you do, remove it. (You can also try to locate the hole in the tube. The distance between the hole and valve will tell you where to look in the tire. You did note which part of the tire was at the valve, didn’t you?)
5. Patch the tube. (Or pull out your spare.) To patch a tube, first find the hole. Put some air in the tube then listen or feel for the leak. (You’ll most readily feel it against your face.) Be sure the tube is clean, roughen it with sandpaper in the patch kit, then brush on a thin layer of rubber cement. Let it dry 5 minutes, then peel the foil backing from a patch, and press it firmly in place. Inflate the tube to be sure it’s fixed.
6. Slightly inflate the tube. Whether using a new or patched tube, you want just enough air in it to give the tube shape, but not enough to make it bigger than the tire. Put one edge of the tire back on the wheel. 7. Insert tube inside the tire. Put the tube inside the tire, working from the side of the tire that hangs over the rim. Start by pulling the valve through the hole, then work evenly from both sides of the valve. Be sure the valve is always coming straight through the hole, not at an angle. Continue around, working the tube in so that it’s completely inside the tire, and so that all of the tube is between the metal rims of the wheel. You should end up with the tube fully inside the tire. One side of the tire will be inside the rim, the other side will be just hanging over the rim.
8. Reseat the tire within the rim. Start at the valve again, and push the loose edge of the tire down inside the rim. Work evenly from both sides of the valve, again watching that the valve doesn’t get crooked. As you finish (opposite the valve), it will get harder. Continue until the tire is fully inside the rim, and seems equally seated all the way around. Do this by hand; using the tire irons could pinch the tube and create a new leak.
9. Work out any kinks. Pump a little more air into the tube, then work your way round the tire, kneading it a bit, peeking inside if possible to be sure the tube isn’t pinched anywhere. Your goal is to work out any twists or kinks that might have developed in the tube, which would lead to another flat.
10. Inflate. Fully inflate the tire, and pause to be sure it’s fixed.
11. Put the tire back on the bike. For a back tire, twist back the derailleur, as you did when removing the wheel. Be sure the axle is all the way back in the slot.
12. Tighten. Tighten the thumb nut, if you loosened it when removing the wheel. Then tighten the quick release lever. It should be quite snug when it’s parallel to the bike. Spin the wheel to see that it moves smoothly and evenly.
13. Reconnect the brake. Check for rubbing. If the brake or frame rubs the tire, chances are the axle is not fully seated and all the way back. You don’t need to remove the wheel to do this; just loosen the quick release lever and try again.If you put the chain onto the smallest gears (to fix a back tire), you don’t want to bike like that. Put it into the middle gears. Congratulations! You never again need to worry that a flat tire will ruin a day of biking.