During the war my grandfather worked as engineer at Gothersgade Elektricitetsværk, a power plant here in Copenhagen and located just beside my workplace (Known as “Turbinehallerne” today, being demolished right now), and his work hours were often such that he had to ride his bike during curfew to and from work. He had a permit of course, but he still ran into trouble a few times. Once a German soldier stopped him, pointed his MP 40 at him and told him in German he could not get through. My grandfather gently pushed the barrel aside and told him in Danish that he had to go to work, that it was important, and that he had a permit. Probably several times, before he was let through.
During the war it was impossible to get new bike tires and tubes, so people had to make do with what they had. Some people also tried to steal bikes for spare parts, and especially tires and tubes were highly sought after.
My grandfathers characteristically ingenous solution to the bike theft problem was to carry a rope and then hoist his bike into a tree while he was at work. He had found a tree where the bike would be completely hidden from sight when you walked by. He never had his bike stolen.
But I learned that patching a bike tube was a very important skill, and to this day I still patch inner tubes a few times rather than just throwing them out, even though they’re so cheap that I might as well buy new ones. It’s just wasteful and environmentally unfriendly to throw them out. Also, being frugal is something I could get better at.
I’m always surprised at how many people don’t know how to patch an inner tube well. Here’s how:
Find the hole. Most often you can hear where it’s leaking, then it’s easy. If the tire is completely flat then just pump some air in it until you can hear the leak or reach max pressure for the tire, whichever comes first.
Should you fail finding the leak you need to take out the tube and fill it with air with a little pressure, and then pass it one part at a time through water and look for bubbles.
If this too fails, then it might be the valve. Try and mount the tube in the tire and pump it up to near max pressure, let out some high pressure air through the valve and blow it clean that way. Pump the tire up to normal pressure again and leave it overnight and see if that helped. If it didn’t, throw out the tube, there’s probably nothing you can do.
If the leak is right next to the valve it can’t be patched either, get a new inner tube.
When you find the hole take note of the location on the tube relative to the valve and inspect the tire at that place. You will probably find the sharp object responsible for the flat still there, so remove it, lest you want another flat in minutes after you start riding again.
Take the wheel off and with your tire levers (the Specialized Prybaby ones are the best ever, if you can find them) get the tire off the rim on one side and pull the inner tube out, the valve last.
With the tube out and the hole found, start with the sandpaper, just to rough the rubber up a little. It also cleans the spot completely.
Then add some glue, just enough to cover the same area as the patch and centered on the hole, and let it dry until it no longer stick to your finger when you touch it. It can take a while, so just find something else to do in the meantime.
Pull the patch off the metal foil and press it onto the glued part, it should stick immediately, and you should be able to just pull the clear plastic film off.
Put the tube back into place inside the tire.
A great trick is to pump just a little air into the tube, making it a lot easier to get it back in, and you avoid getting the tube stuck between the tire and the rim when you mount the tire back on, which–unnoticed–will result in a new flat tire when you pump it up again.
And since you now have dirty hands and are working on your bike, check the tires for whatever little stones might lie buried in the rubber and remove it, and check for cuts. You can sometimes repair cuts by filling them with glue, but I’m not sure how effective it actually is.
I created Flickr set of the pictures with a few more pictures for illustration.