Techniques for patching a tube [closed]

Question

I asked this question and got very good answers, but now I have a related question.

Do you have any special techniques for patching a tube outside of the generic instructions that are supplied with patch kits, if so feel free to post them, this can include how to locate the leak, buff and clean the area, how to mark the position as to center the patch, etc.

We can assume this is patching done at home and not on while we are on a ride, but you can post techniques for that also, but please make a note about a repair while on a ride.

Comments on types and brands of patches welcomed if they are not already covered in my original question linked above.

Let the Patching advice begin!

Answer 1

Generally you should use a patch kit similar to this , which consists of patches with rounded corners & feathered edges, a small tube of glue, and a bit of coarse sandpaper.

Usually you can locate the leak by over-inflating the tube (to about twice normal diameter) and then either moving your hand along it or moving it around near your face (your face skin is quite sensitive to air movement) to feel the leak. Sometimes it helps to move it around near your ear to hear the leak. As a last resort, fill a basin with water and use that to detect the bubbles.

Discard any tube with a leak within two inches of the stem, or with a leak within an inch or two of an existing patch. And of course discard any tube with a slit or blowout (except in extreme emergency).

Marking is tricky. Often the leak is near enough to the center of the tread area that you can simply center on the tread area and only need to mark the position around the circumference. Other times the leak is more on the sidewall, and you need to mark both X and Y (so to speak) positions. (Or you can wing it and try to remember where the leak is.)

But remember that you need to abrade the area of the patch (plus at least a half inch beyond its margins) and then spread glue on this area. This will obliterate any nearby marks, so you need to mark farther away than that. It's often best to mark on both sides, so you can conceptually draw a line between the marks.

Chalk, a soft pencil, or a fine-tipped felt pen can be used for marking. (Be sure to test marking first and be sure you can see the mark.) Avoid using a grease pen, since the grease may get onto the patch area.

Abrade the area of the patch. If the patch will fall on top of the mold sprue (seam) on the centerline of the tube, you need to abrade that pretty well -- not necessarily enough to remove the "seam", but enough to make it lay flat.

Spread on the glue, going about 1/2" beyond the patch margins. You don't need a lot, but enough to make the whole area shiny and smooth. (Note, you WILL get glue on your fingers, especially since the finger is the best way to spread the glue. Be prepared with some sort of towel to wipe your hands, and don't do any of this on your wife's new hardwood diningroom table, nor should you wipe your hands on the upholstery of the new couch.)

Allow the glue to dry. Here I may diverge from "conventional wisdom" and the instructions in the patch kit, since I like the glue to be not quite totally dry before applying the patch. Others like it thoroughly dry, but I find I get better adhesion my way.

Apply the patch. It comes with a clear plastic top cover and a foil backing. The trick is to remove the foil without removing the clear plastic, so that you can use the plastic to cover some of the glue while pressing. After the patch is in place, press it thoroughly, by, eg, rubbing your fingernail back and forth across it. (The smooth, rounded end of a plastic tire "iron" is useful for this function.) It's important to do this pressing well, crossing the patch first one direction, then another, applying considerable pressure.

If the patch is on the sidewall where you will fold it while folding up the tube for stowage, allow the patch to "set" for at least another 15 minutes, preferably a couple of hours. And, before folding for stowage, place a bit of tissue over the glued area (even if the clear plastic is still covering it) since the glue, over time, will want to stick to parts of the tube it touches when folded. (Another option is to thoroughly dust the area with talc.) You need the same consideration when installing the tube back in the tire, to prevent the patch from sticking to the inside of the tire. (In a pinch, when you need to put the tube back in a tire and ride immediately, roadside dust is a good stand-in for talc.)

Answer 2

After having done this way too many times....and especially on the road....and assuming that an extra tube is unavailable.

1. Remove tube.
2. Find the leak.* This is easier if you have a pump since you can pump up the tube and go by feel. If you have CO2 cartridges, you don't want to pump up the tube, since you'll waste the CO2. So it's basically, a visual inspection.
3. Rub the sandpaper or other abrasive around the leak. (Not an extreme process, just rough up the rubber around the leak site a little bit)
4. Apply rubber cement around the leaky spot in an amount that goes slightly beyond the patch size. Use your fingers to smear it around a bit.
5. Wait a few minutes. 2 - 5 minutes or so.
6. Remove the foil from the foil side of the patch. Then, press the appropriately sized patch onto the tube with your fingers. (You can't be too delicate, just push the patch into the rubber of the tube)
7. Put the tire back together. Pump it up. And go.

Now, finding the leak can be a problem... One method is to carefully run your fingers around the inside of the tire. If it's a nail, bit of wire, a thorn, etc, you'll feel it and identify the tube leak location. -- With a pump, you can pump up the tube...on the road you can feel the leakage location*; at home, you can immerse the tube in water and see it. -- On the road with only CO2, you'll need to learn to identify leaks visually.

**Find, the leak location on "the tire". If it's a bit of wire, or a nail, or a thorn, etc...you'll immediately get another flat. So, check the tire. And this applies whether or not you have a spare tube.

Answer 3

Park Tool Co. sells a kit of pre-glued patches, i.e., http://www.parktool.com/product/super-patch-kit-gp-2

They are a bit more expensive than regular patches, but you don't have to bring the rubber cement with you and you don't have to wait for the time that the cement gets dry.