How to Repair a Bicycle

Everyone who's ever pedaled a bicycle has had a flat tire one time or another. Don't let flats put you out of commission -- mend the tire yourself.

Tools: adjustable wrench, chalk, two tire irons, bicycle pump, bucket, bicycle tire pressure gauge.

Materials: rags, bicycle tire patch kit, talcum powder.

Time: about 1/2 hour.

To give you access to the damaged tire, remove the wheel from the bike.

With an adjustable wrench, loosen the nuts that hold the wheel in place. For the rear tire of a single-, 3-, or 5-speed bike, remove the break band attached to the lower frame of the bike; unscrew the screw that holds the metal band and remove the band. Remove the wheel from the bike frame.

Carefully examine the wheel for nails, glass, or other sharp objects; pry out any sharp object wedged into the tread, and mark the damaged spot with chalk. Then remove the tire from the wheel. Pry the tire off by hand, if possible; press firmly with your thumbs to work the tire over the rim. If you can't remove the tire by hand, use bike tire irons. Don't try to use screwdrivers or any other sharp-bladed tool; you could damage your tires.

Starting at a spoke, insert the plain end of a tire iron carefully between the rim and the tire; make sure it's firmly held by the edge of the tire. Keeping that end of the tire iron in place, pull the slotted end down and behind the spoke, and hook the slot over the spoke to hold the tire iron firmly in place. Insert a second tire iron at the next spoke and repeat to pry more of the tire off the rim. Repeat, moving tire irons alternately around the rim, until you can work the tire off the rim by hand. Then carefully remove the tube from the tire, pushing the tube valve through the hole in the wheel rim and pulling the tube gently free of the wheel.

Use a bicycle pump to fill the tube until it's firm. Then, with a bucket of water, look for the leak in the tube. Hold a section of the inflated tube underwater and watch for air bubbles; turn the tube in the water until you locate the leak. Check the entire tube; there may be more than one leak. Remove the tube from the water, wipe it dry, and mark the bad spots with chalk.

Bike tire patch kits usually include a roughing device. With the roughing device or the top of the kit, scrape the damaged area of the tube to clean it and provide a rough surface for the patch to bond to. Apply a coat of adhesive to the scraped area of the tube, as directed by the instructions in the patch kit. Let the adhesive dry as directed.

Choose a patch of the appropriate size and peel off its protective backing; press it smoothly and carefully into place over the glued area. Press firmly to seal the patch in place, making sure the edges are entirely bonded. Let the patch dry for 5 minutes and then sprinkle it with talcum powder so it won't adhere to the inside of the tire.

Check the tire once more, inside and out, to be sure nothing sharp is still wedged in it; remove anything stuck in the rubber. Press the uninflated tube into place inside the tire. Carefully insert the valve stem of the tube into the hole in the rim, and push the tire into place over the rim with your thumbs. When it gets too hard to replace the tire by hand, carefully insert the plain end of a tire iron under the tire and pry the tire into place around the rim. Work gently, being careful not to pinch the tube between the tire and the rim or the rim and the tire iron. Use the tire irons only when necessary.

Finally, with the tire in place, inflate it to the correct pressure with the bicycle pump, as marked on the side of the tire. Wait a few minutes to make sure the tire is holding air; then replace the wheel in the bike frame and tighten the nuts that hold it in place. If necessary, replace the break band.

Tires aren't the only part of a bike that take a pounding. Bike chains often become damaged, too. We'll cover how to care for, clean, and replace a bike chain next.

For tips on caring for and repairing other types of sports equipment, try the following links: