I am aware that brand new tubes are cheap, but I want to practice my patching skill, which is quite essential on the road. I tried a few more times since my second, failed attempt until I used up all the patches in the kit and eventually ruined the tube, making it impossible to repair. While I am waiting for another punctured tube to become available so that I can refine my patching skill, here are some key takeaways.
- Two pinch cuts in the area with molding lines. We need to use sandpaper to remove the ridges so that the patch can stick to the tube without any gaps. These two pinch cuts are tricky to fix because the patches need to have a margin of 1 cm from every side of the hole.
- I ran out of big patches so I tried with the small ones. Apparently, it is not big enough and air leaks from one of the two holes.
- I experimented with patching on the leaking patch. I put too much glue there and ended up having to wait for more than 30 minutes for it to dry completely. One thin and even layer of glue should do the work. This patch on patch managed to keep the tube inflated after hanging for days. However, after putting it inside the wheel and pumping to 50psi for around 20 hours, it’s already showing signs of leakage (see the tiny bulges). In an emergency, this might be enough to bring you home.
- I cannot put this double patch to test on the road because I had some more pinch cuts. I failed to properly install the rim tape (the kind of tape with adhesive side to stick on the rim). Somehow one section of the tape did not cover the spoke nipple hole and failed to protect the tube. Sorry, no pictures to show here. I am too ashamed of myself to take one.
- This is how I ruined the tube. I tried to tear off a leaking patch and ended up tearing the hole and made it so much bigger that it became impossible to repair. That put an end to my experiment and struggle. According to Jobst Brant on Sheldonbrown.com, one should apply some heat with a hot iron or heated frying pan on the patch with a thumb until heat is felt. Maybe a hair dryer would do the trick, too.
- This metal scraper may be good enough to scuff the surface of the tube before applying the glue because one can even rub the rubber against the concrete pavement in emergency cases. However, I prefer a small piece of sandpaper because it would not scratch another hole on the tube even if we are getting impatient.