5

One of the things that I've noticed with the low-cost tube patch kit that I bought is that I'm able to catch an edge of the glued patch with my knife or fingernail and peel the patch off the tube like a bandaid. While handy for repatching, it doesn't give me a whole lot of confidence in this kit.

Shouldn't a glued patch be essentially so welded to the inner-tube that it's unable to come off through any normal means?

** This is a cheap kit with glued patches (ie, separate glue and patch, not a "glueless" patch)

  • 1
    Why are you using a cheap patch or pulling it off. A patch is to get you home and then you install a $4 new tube. – paparazzo Nov 8 '15 at 21:58
  • @Frisbee, that's one take. I find glued patches last as long as new tubes, and change the tube at the side of the road, patching in the warm and dry when I've saved a few tubes. What I think we will agree on is that good glued patches are the way to go. – Chris H Nov 9 '15 at 9:33
  • 1
    Personally i find that biggest problem I've had with glue not sticking was due to not giving enough time for the glue to dry before applying the patch, or that the glue has gone bad. Best to try these possibilities before looking for other problems. – Kibbee Nov 9 '15 at 13:49
  • @Frisbee, can I have your old tubes if you chuck them after one puncture? If you do it right a patched tube is as good as a new one. – stib Nov 12 '15 at 11:06
  • 1
    I bet you also use the old tube when replace a tire. Too right I do! I'm not allergic to money like some cyclists seem to be. – stib Nov 13 '15 at 3:00
6

No, you shouldn't be able to peel a patch off, regardless of if its a glued or glueless patch.

Confirming that this is a wet-glue patch that has failed to stick? Possible causes for failure of a patched tube

  • You didn't clean the tube properly
  • you didn't buff the tube properly
  • There is a ridge in the tube which is in the way, has left a tunnel of weakness under the patch
  • its a latex tube not a butyl rubber tube
  • The patch was cheap and/or nasty, or possibly old, or damaged by heat/sunlight.
  • The rubber cement was cheap (watered down or just not very good)
  • The cement was really just a glue (cheap again)
  • The cement was old, more-so if it had been sitting around open for a while since your previous puncture fix.
  • You didn't wait long enough for the cement to dry - 10 minutes is my normal wait time.
  • You didn't spread the cement out far enough on the tube. It should make a wet area bigger than the patch.
  • You stuck the patch on upside-down, so the wrong side was out
  • When unpeeling the patch backing you touched the surface, and left finger oil or other contaminants enough to interfere with bonding
  • You didn't press the patch on firmly to the tube. I use a tool as pictured below, but a round coin works well too. You have to roll it over the whole patch, back and forth over and along the edges
  • Did you inflate the tube outside the tyre? Without restraint, the tube will stretch, which causes extra strain on the cement.

These aren't likely to be the cause of the patch peeling off

  • You missed the hole completely, or far enough so that it was to the edge of the patch
  • The hole is too big to be patched. Cuts over 5 mm generally mean a new tube, and holes more than 2 mm in diameter tend to not patch so good.

EDIT: Other points I missed * patching in the rain or dampness - water/cold stops the cement from curing as quickly, and being wet makes you hurry.

Personally I'm not very good at punctures, I have a success rate of 2/3 repaired okay if I start patching a tube.

In a pinch, I've successfully cut a round piece of spare innertube, buffed and glued its innerside, waited 10 minutes and slapped it on the buffed and glued inner tube. It worked perfectly and is still on the bike today.

I know yours isn't a glueless patch, but for completeness:

By comparison, glueless patches are really glorified stickers. They don't bond to the rubber of the tube as well as one with vulcanising fluid/cement. But they're also a lot quicker to buff, slap on and ride more. Their maximum pressure seems to be lower too, so bad for roadies on 100psi, workable for MTB on 30psi.

  • This doesn't quite answer the question asked ("Should I be able to peel it off") but rather the followup ("Why isn't it sticking properly"). Can you add a preamble saying that a properly glued patch shouldn't be peelable (if that's indeed the case). – RoboKaren Nov 9 '15 at 2:25
  • @robokaren Fair call. Done. – Criggie Nov 9 '15 at 2:45
  • 1
    From that list of failure modes, I'd say most likely: Impatience with the glue; bad/old/not enough/uneven glue; not sanding the tube. I'd also add patching in the rain, as rain on the glue/patch/tube spoils the job, and sitting in the rain makes you rush. That's why I reckon on swapping tubes. – Chris H Nov 9 '15 at 9:36
  • @chrisH Good point - I've added that. – Criggie Nov 9 '15 at 20:53
3

This is normal behavior.

The reason why many regular patch kits (adhesive separate from the patch) work well is because they use a vulcanizing fluid to bond the patch to the tube. Glueless patch kits (i.e. ones which have the adhesive pre-applied) and some regular patch kits use normal adhesives, which aren't nearly as strong at bonding the patch.

That being said, some glueless patch kits are better than others. Try a different brand or go back to using old fashioned patches with vulcanizing fluid.

Also, it goes without saying that applying the patch properly (see manufacturer's instructions) normally gives the best strength as well.

  • 3
    Regular glue contains no "vulcanizing" components. Vulcanizing occurs under high pressure and temperature (normally, around 170 deg C., or about 350 deg F). Regular patches adhere well because the adhesive is better. If actual chemical vulcanization were occurring, the adhesive and patches used for latex tubes would be different from the adhesive and patches used for butyl tubes since latex and butyl are chemically different. – R. Chung Nov 8 '15 at 17:40
  • I'm using a patch kit with separate glue. I amended the question to be clearer. – RoboKaren Nov 9 '15 at 2:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.