Patching Tubes

  If your tire doesn't hold air, but the tire itself looks fine you can try patching the inner tube. Generally a patch kit is cheaper than a new inner tube, and you usually get around 6 patches. If you have the traditional kit with glue you first scuff up the tube around the puncture. Clean the area with rubbing alcohol if it's dirty, then smear some rubber cement around the scuffed area. Let the glue dry first (wait like a minute or 2), then peel the patch off the foil and press it onto the center of the hole as hard as you can for 30 seconds. After a few more minutes you should be good to ride (although it's best to let the patch cure overnight if you're doing this at home). Always check the inside of the tire for debris, and the rim strip for exposed holes or spokes before replacing the tube.

   There are several different types of punctures, and knowing how they happen can help you avoid at least some of them. These are the most common kinds:
 - Debris Puncture - Not much you can do about these other than avoiding the very edge of the road where glass, thorns, and metal shards tend to collect. You can usually see these sticking through the inside of the tire, and these will create small holes in the middle of the tube on the outside. These are the most common, and easiest to patch.
 - Pinch Flat - These usually happen when you hit a hard bump without enough air in the tire. The rim itself will cut the tube on the inside of the tire, and there will usually be two small holes or slits in the tube near the rim's edge. These are common for dumb mountain bikers like me who ignore the minimum pressure on the tire's sidewall. Usually you'll need two patches to fix the tube.
 - Valve Tear - This happens when you install the tube with the valve sticking out at an angle and inflate to full pressure. The tube tends to tear at the base of the valve, and this is not patchable. Make sure your valve stems are straight.
 - Rim Strip Puncture - Sometimes you might see a single hole on the rim side of the tube. This happens when the rim strip or tape moves around and exposes one of the spoke holes. The tube will try to fill up the uncovered hole in the rim and then burst. This can also happen if the bare spokes are poking through the rim strip. For this case you must fill up the area around the spoke(s) before adding the rim strip. I usually make a small ball of duct tape and stick it on the spoke under the rim strip to protect the tube. In any case I recommend using adhesive cloth tape since it won't shift around as easily as a rubber strip.
 - Mystery Puncture - This happens when you can't find anything in the tire and the rim strip is fine. Sometimes it's a defective tube, other times its a tiny steel wire embedded in the tire (a cotton ball will snag on this). Or it could be a previous patch that opened up.

   In any case good luck, and hopefully you don't have to actually use any of this advice. Remember that the glue in those little bottles dries up after you open them, so a glueless patch kit (Park Tool brand works well) may be the way to go on the road.