Patching Bicycle Tubes

By John Wente

There’s no reason to throw away a tube that has only a small puncture. With a little care and the advice given here, anyone can successfully patch a tube.

About Patches

  1. Get the right size patches. The patches that come in most patch kits are WAY too large for a road bike tube. Ideally, the patch should be no larger than a dime. If you find a particular brand of patch kit you like, be sure and let your bike shop know so they will keep them in stock.
  2. The cheap patch kits sold at Wal Mart (and other discount retailers) usually contain some very large round patches (possibly suitable for patching a tractor tire tube). Many of these kits also include some large rectangular pieces of patch material. Some have had success in cutting small circular patches from this material. It won’t have the nice tapered edges of a good bike patch, but once it’s inside the tire, that will make no difference. If small patches cannot be found, this may be the only remedy. It’s better than trying to use the big patches intended for mountain bike tubes. And you can cut to shapes other than round if that seems to be best for the situation at hand.
  3. A punch designed for making holes in automotive gaskets can be very handy for making small round patches from sheets of patch material (or larger round patches). These can be bought in various sizes at auto supply and tool stores. An 11/16″ (17mm) or 3/4″ (19mm) punch should be about right.

About Glue

  1. The glue in those little tubes that come with a patch kit will dry out fairly quickly once the tube is opened even if the cap is securely in place. If you carry a patch kit on the bike, carry a glue tube that has not been opened.
  2. Check the glue tube in your on-bike patch kit periodically to see if it has dried out (you can tell by squeezing the tube a little).
  3. The cheap patch kits sold at Wal Mart (and other discount retailers) have a much larger tube of glue than bike shop patch kits. Buy one of these cheap kits and use the glue for patching tubes at home. That way you can keep the unopened glue tube in the patch kit you carry on the bike. The glue in the cheap kits in many cases seems to be superior in sticking power to the glue found in many “high quality” patch kits.
  4. You may even be able to buy just the patch glue at auto supply stores if you don’t want the cheap patch kits, but chances are it will cost as much or more as a patch kit at Wal Mart.

How to Apply Patches

  1. When applying the patch, center it as nearly as possible over the puncture.
  2. It’s much easier to get a patch to stay on the tube if you clean the area with lacquer thinner, use the little piece of sandpaper that comes in the patch kit to rough up the surface of the tube just a little, then use the lacquer thinner again after the sandpaper.
  3. Apply glue to the tube in an area larger than the patch. Also apply glue to the patch and let it dry until it looks dull before applying the patch to the tube.
  4. Rub the patch area firmly and thoroughly with the bowl of a spoon or a tire lever.
  5. Clamping the patch to the tube is also a good method (optional). Use a small “C” clamp and a couple small pieces of wood you’ve sanded smooth (especially the edges). Clamp tightly for 5-10 minutes.
  6. Don’t inflate the tube outside the tire for at least an hour after applying the patch.
  7. Don’t even try to patch a tube when it’s raining or foggy out. The humidity makes it nearly impossible to get the glue to stick.
  8. After applying the patch, dust the area generously with baby powder so the tube won’t stick to the tire when it’s installed.

CAUTION: Lacquer thinner and rubber cement produce noxious fumes. Always work in a well ventilated area.

Testing Patches

  1. Wait at least an hour after applying the patch before inflating the tube outside the tire.
  2. Put about 2-3 inches of water in a sink or dish pan.
  3. Inflate the tube until it is about 3-4 times it’s uninflated diameter.
  4. Lower the tube slowly into the water so as not to cause a lot of disturbance in the water.
  5. Watch the patched area carefully for tiny bubbles escaping around the edges of the patch.
  6. After testing, dry the tube thoroughly and dust with baby powder before.storeing.
  7. If a patch is leaking, it can sometimes be removed and a new patch applied. However, in some cases, the old patch does not come cleanly away and it will be nearly impossible to get a new patch to stick and be leak-free. Time to discard that tube.