Inevitably, we've all been out on a bike ride and gotten a flat tire. If this hasn't happened to you yet, count yourself lucky. If you still haven't repaired a flat because you're SO new to this you haven't gotten one yet, I'm here to share all of my heard-earned knowledge.
To Fix a Flat:
1. Stop riding your bike. Now.
The second you notice that something is amiss with the amount of air in your tire, quit riding the bike. Even if there is still "some" air in the tire, don't ride unless you REALLY want to replace the wheel. If that is your goal, feel free to keep riding!
2. Empty the tire/tube of air.
If there is any air left in the tube, release is by pressing on the air valve.
3. Remove the wheel.
Turn the bike upside down (it's easier this way, trust me) and remove the tire. If your bike isn't quick release, get out your crescent wrench and loosen the bolts. It might be necessary to release the brake pads to get the wheel through the brake pads so go ahead and do that if you think it's a problem. Don't break the brake.
* It is possible to patch the tire without removing the wheel but that's a more advanced trick. Maybe you could try after you've mastered the basic steps?
4. Remove the tire from the wheel using a plastic tire lever.
5. Remove the tube from the tire.
Before doing this, be sure to mark the place on the tire where the valve was. This will make it easier to go back through the tire to attempt to remove the culprit if it's still in there. That's actually a really important step. If the culprit isn't removed from the tire, it will just give you another flat. That's no fun.
6. To patch or to replace, that is the question.
Any hole except for a blowout can be either patched or replaced. A blowout has to be replaced. Tubes and patch kits are cheap at bike shops. When buying your patch kit, don't buy the glueless assortment because they don't actually work very well.
7. Find the leak in the tube.
Do this by pumping the tube up to a little overinflated. The leak will be obvious. Mark the spot with a circle and an X.
8. Prep the tube.
Release all of the air again. Use sandpaper or a metal file to scrape the area really well. This helps the glue bond to the rubber better.
9. Apply the glue in a well-ventilated area.
The well-ventilated area is the key. Breathing in the fumes from the glue is bad for you. The glue needs to be applied to a larger area than the patch in size. After applying it, allow the glue to dry.
10. Apply the patch.
Don't remove the clear plastic cover until AFTER the patch is on the tire solidly. This will let it bond better. Also, if your patch moves or comes up when the clear plastic is removed, you need to do one of the steps better in the future.