How to correctly use a bike tube patch kit

A recurring theme in bicycle discussions is the use of patch kits to fix flat tires. Some people claim they work poorly and are unreliable, while others claim they are great and last forever. Who is right? I'll go ahead and agree with the latter, that they are very reliable and will last as long as the rest of the tube will, but only when used correctly. I think many people do not use patch kits correctly, which is the root of the problem! (Tuning up your bike and not sure if everything is being covered? See my tuneup checklist.)

Instead of just saying "follow the instructions in your kit" in an article on fixing flats, let's review a little more in depth with the most common type of patch kit, which uses vulcanizing glue (all the vulcanizing kits are pretty much the same, though I've heard good things about the Rema Tip Top TT-02).

It should include patches, glue, and sandpaper at the least. I also store spare valve caps and a presta-to-schrader valve adapter in the little box. The instructions often have just pictograms (if there even are any), but there are important nuances that shouldn't be glossed over!

1. Once the leak in the tube has been found, rough up the area with sandpaper (to expose fresh rubber) and blow away dust, doing your best to keep things clean
2. Apply a small amount of glue to the tube (not the patch or tire), spread a thin, even layer with a clean-ish finger, and then wait 5 minutes—I think the problem is that no one does this 
3. Now the area will no longer be tacky. Remove the foil backing, apply the patch, press firmly, and wait another few minutes before inflating. Don't put any glue on top of the patch or in the tire.

That should work! A botched patch job might need a new tube, though sometimes a second offset patch will work (haven't needed to do this in years). I find that most tubes can be patched at least five times by the time something irreparable happens, such as a hole next to the valve stem.

For extreme detail on preventing flats and finding root causes, look no further than Sheldon Brown's site.

-Mike