If done correctly, patching can revive your tubes and save you tons of money!
Tools You'll need for the Job
Bicycle Tube Patch Kit (includes: sand paper, glue, and patches)
Pump or CO2 inflator
Time Required: 15 minutes
Most punctures are small enough to be quickly patched without too much headache. After removing the tube, if you follow these steps, it will be simple!
Step 1: Find the hole. Pump up the tube to the point where it is fairly inflated. Move your hand around the tube feeling and listening for air leakage. If you can't feel the air with your hand, try bringing the tube close to your lips. This sounds weird, but your lips are very sensitive and can feel small amounts of air easier than your fingers. If you still can't find where the air is leaking, you can submerge the tube under water looking for bubbles. Don't forget to close the valve before you submerge!
Step 2: Rough up the tube. This is an important step! Use the sandpaper to rough up the rubber of the tube around the puncture. I like to scrape the tube in a few multiple directions to make sure that it is sufficiently scraped. It's not like sanding woo,d where you only go with the grain. Scrub it up pretty good! Also, make sure you scuff up a surface area that is quite a bit bigger than the size of the patch. If you try to stick the patch onto a spot that hasn't been roughed up, it won't adhere correctly.
Step 3: Apply glue. Apply a thin, even layer of glue. Apply it to an area that is bigger than the patch so that you get good adhesion on the entire patch. Let the glue dry completely! Many people try to stick the patch on when the glue is wet, but this in wrong! Let the glue dry completely. That is how it is designed and how it adheres best!
Step 4: Apply the patch. Usually patches will come in between a piece of foil and clear plastic. The side of the patch that is supposed to touch the tube is the smooth side, which is the foil side. I like to remove the foil but not the plastic piece. So, with the patch still stuck to the plastic, press it onto the tube with the puncture hole directly in the middle of the patch. Put the tube on a table or hard surface and push down to ensure that it adheres in the middle and around the edges of the patch. After 20 seconds of pushing, slowly peel back the plastic wrapper and inspect the patch. None of the edges should be peeling back around the whole patch.
Step 5: Check the patch. When you're all done patching -- and you think you did a good job -- do this last step before re-mounting the tube and tire. Pump up your tube a little and look, listen or feel if any air is escaping from around your patch.
Trick of the Trade
I like to put a little bit of air in the tube right before I put the patch on. I put just enough air in the tube so that it gives it about the same amount of shape that the tube would have when inflated inside your tire. By doing this, your patch won't be stretched out when it is pumped up to full pressure.
If you're installing a new fork, the use of a threadless headset allows the steerer tube to be cut to a length that will fit several different frame sizes. With that said, the old adage of "measure twice, cut once" is still a great rule of thumb when cutting steerer tubes to fit frame/headset combinations. When cutting a steerer tube, it's a good idea to leave a little extra just in case you decide to use the fork on a different frame or swap out the stem for something that is a little taller.