These thin, vulcanizing bicycle tire repair patches are really the only kind of patches that create a reliable repair on a high-pressure tube. Don’t leave home without them!
For 22 years my husband and I led bicycle touring road trips. This is the only kind of patch kit that we found to be reliable. At that time they were made in Germany. (I believe they sold under the name Velox. You would think that I should be able to find one of those small green metal boxes around the house... we must have used hundreds of them, but I can’t.)
We suddenly found our situation changed, and neither one of us did much biking for several years. When I bought myself a new bike I asked for some accessories for Christmas, and my husband found basically the same patch kit from Genuine Innovations.
The kit contains an instruction sheet, glue, sandpaper, and eight vulcanizing patches: four 1" rounds, two 1/2" rounds, and two 3/4" x 1 1/4" rectangles. Vulcanizing means that the two layers of rubber actually melt together. If these are applied properly they will not leak around the edges.
First you need to find and mark the hole. If you placed the tube in water to do that, dry it off. The tube must be dry and clean. Then lightly rough up an area larger than the entire patch with the sandpaper. Don’t overdo this, but at the same time be sure that you have thoroughly roughened the area. Each patch is black with an orange edge. It’s that orange edge that is SO important, so be sure you’ve covered an area which includes that size.
Then apply a thin and even layer of glue over the entire roughened area, and slightly beyond the full size of the patch. LET IT DRY COMPLETELY. Don’t get impatient and move to the next step when there are still wet streaks.
Peel the foil backing off the patch you have chosen to use. Place the patch over the glue and stretch the tube with your thumb and fingers, working that orange edge “into” the tube. Generally “work it” from the center of the patch outwards. Keep stretching and working it until those edges have sealed right to the tube. Spend at least 30 seconds doing this. While you have been doing this the clear plastic layer that was on the top of the patch will probably have worked loose. If it is not completely off at this point, finish removing it.
Let it dry for another couple of minutes while you are checking your tire for what caused the flat in the first place, and check your rim for spokes which might be poking through. If you don't eliminate the cause of the flat, you'll be stopping again in 5 minutes. Overinflate the tube to make sure the patch is sealed. Then deflate to just enough pressure to make it hold its shape and remount your tube and tire.
If it is not sealed, it is your fault not the fault of the patch. I can make that accusation because I’ve been there, done that. Just rip it off and start over with a new patch. (No cussing, now... be nice.)
In our experience the large rectangular patches are a bit optimistic. You might want to use them for a set of holes side by side (read pinched tube while removing the tire, grr). But if you have a tear in the neighborhood of 1/4 inch or more, a patch is not going to fix it. Save your time and just install a new tube.
You don’t get a nice little hinged, green metal box, but the patches are still great. And these are made in Taiwan. I get memories of sitting under highway underpasses in the pouring rain, with water dripping off my hair onto the tube while I tried to dry it off enough to patch it. You might not miss those memories, but I kind of do!