How To: Patch a flat tube
Don't toss those popped tubes! Patch 'em! A good patch becomes the strongest part of the tube. In fact, you can patch a tube many times and keep right on using it. Knowing how to patch comes in handy, too, when you're on a ride and discover that your spare tube has a hole in it.
You'll need a patch kit, pen, pump and, of course, your punctured tube!
Find the hole:
Inflate the tube listening for a hissing sound and follow it to find the hole. If you can't hear a hiss, hold the tube next to your face (or lips; they're especially sensitive) as you search for the hole, and you should feel the escaping air. If you can't find the hole, try adding more air. Still no luck? It's probably a really slow leak. To find it, submerge the tube in water and look for bubbles. Can't inflate the tube? There's probably a hole in it so large that the air leaks out immediately. Look for it or have a friend listen and look while you pump.
Tip: If the tube has a tear 1/2-inch long or longer, has several holes in it or has a hole next to the valve, it'll be difficult to impossible to patch. Time to buy a new tube. Use the old one to make a water-balloon slingshot.
Mark the hole:
Tip: Be gentle when marking the tube by tearing, especially on lightweight tubes, which are fragile.
Sand the tube:
Tip: You can also blow the dust off the tube but your breath is moist and you don't want to wet the tube. So blow carefully.
Apply the glue:
Tip: It may seem counterintuitive, but the glue must be dry before applying the patch. You can wait as long as you want -- even weeks As long as the dried glue remains clean and free of dust and dirt, the patch will stick to the tube perfectly when you get around to applying it..
Patch the tube:
Tip: To ensure that the repaired tube won't let you down, it's best to give it a final check by inflating and listening for leaks or submerging the tube and looking for bubbles. If you find another hole, patch it, too!
About "glueless" patches:
Tip: A glueless patch doesn't become a permanent part of the tube the way glued patches do. So glueless ones work best as temporary repairs. It'll get you home, but you may find that the tube slowly leaks air. No problem. Simply replace it with a new tube before your next ride.