- Field Skills
The best way to avoid a flat tire is to keep your tires properly inflated and check for tread wear regularly. Despite these precautions, there is a good chance that at some point a road or trail hazard will cause you to have a flat tire. (You may want to print off these instructions and carry them with your tool kit in a bicycle bag.)
"Fixing a flat is easier than many riders think. With practice, it will become only a small inconvenience," says L.L.Bean bike expert Jackie Peppe. Here is how you make the repair:
- Find a safe place to change your tire. Move well off the road or trail, so you won't be in the way of motorists or other trail riders.
- Remove the wheel. If the rear wheel is flat, shift the rear derailleur until it is on the the smallest cog before removing it.
- Deflate the tire completely. For a Schrader valve, remove the valve stem cover and press the center pin. For a Presta valve, remove the valve stem cover, unscrew the valve pin part way and press down.
- Remove the tire and inner tube. Insert the spoon-like end of a tire iron between the tire bead (the reinforced edge of the tire) and the rim at the spot directly opposite the valve. Scoop the tire iron toward the tire and hook the other end around a spoke. Insert a second tire iron under the tire bead a short distance from the first. If the tire is a tight-fitting road tire, the second tire iron will have to be farther away from the first than when fixing a looser- fitting mountain bike tire. If the tire is still tight, hook the second iron to a spoke and insert a third iron a few inches from the second one. You should be able to slide one of the irons along the rim to loosen the entire bead. The bead on the other side of the tire does not need to be removed from the rim.
- Remove the tube from the tire. If you are replacing the tube, carefully remove the valve from the valve hole first. If you are patching the tube, leave the valve intact.
- Inspect the tube. Pump up the tube and locate the hole(s): Two holes, or a "snakebite," is probably from a pinched tire (generally caused by inadequate inflation). One hole on the inner circumference is usually caused by a spoke or spoke nipple puncturing the tube. Find the offending spoke and fix it (or pad it with duct tape) to protect the tube. A single hole in the outer circumference, is most likely caused by a puncture. Look in the tire casing to make sure the cause of the puncture is not still embedded in the tire. A slit of 1/2" or more or a star-shaped hole in the tube is probably beyond repair.
- Repair the tube. Choose a patch large enough to cover the hole. "Toughen" the area around the hole with sandpaper, making the abraded area slightly larger than the patch. Make sure that the abraded area is clean and dry. Spread a thin layer of glue over the entire area the patch will contact. (The most common cause of patch failure is not covering a large enough area with glue.) Wait for the glue to dry. Its appearance will go from shiny to dull. Peel the backing off the patch and apply it over the hole. Press the patch onto the tube carefully, especially on the edges. A glueless patch can also be quickly applied as a temporary solution.
- Reinstall the tire. Partially inflate the tube. Insert the valve stem through the hole in the rim. Stuff the tube into the tire all the way around, then insert the tire bead into the rim at the valve stem and continue along the rim in both directions until the bead is one-half to two-thirds on the rim. Continue to insert the tire bead into the rim all the way around. As you work, you may want to deflate the tube to make it easier to work with the tire. If the process becomes difficult, do not use your tire irons, a screwdriver or any other tool to make the last bit of bead fit over the rim, the likelihood of a pinched tube is too great. Instead, work the bead onto the rim with your hands. Examine the tire bead all the way around the wheel to be sure the tube is totally inside the tire and not caught between the bead and the rim. You should not be able to see any of the tube. If the tube is caught, roll the tire between the palms of your hands to work the tube into the tire.
- Partially inflate the tire. Inspect the bead to make sure it is engaging with the rim properly. (Don't forget to check both sides of the tire.) If there are any bulges or places where the bead dips, deflate the tire slightly and re-seat the bead as described above. Once the tire is properly seated, inflate it to the recommended pressure. Some frame pumps require a lot of strokes to get the tire full. Put as much air into the tire as you can, then top it off with a floor pump when you get home.
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