RubeRad

Sorry, this is kind of elementary. Last night I was helping my son patch a tube (goathead puncture). It would have been faster (and apparently better) if I just did it myself, but I want him to learn so he can become self-sufficient on the road.

Anyways, he found the hole, roughed up the area, put the vulcanizing glue on (Park VP-1), and then when he put the patch on, he missed the hole. So we quick ripped it back off, put some more glue on, and slapped another patch on. Seemed to hold. So he put the tube&tire back together and pumped it up, 35psi (mtb front tire), seemed ok.

This morning, flat.

OK, so, any advice on how to recover from a patch fail like that? If the patch goes onto the vulcanizing fluid and then gets ripped off, is the area just unpatchable afterwards? Is this tube trashed now?

More generally, something I've always wondered. When you find a hole (which is usually hard enough to find and see when air is coming out, but completely invisible when deflated) how can you mark the location of the hole, in a way that will remain visible even through abrasion and applying glue, so you can confidently center the patch on the hole?

My two ideas (probably bad) are: white chalk -- but you have to make a fairly big bullseye and aim for the center. Or: use scissors to embiggen the hole to like 1-2mm diameter, so it's obvious.

Any other handy tips?

Booger1

Blow up tube,find hole,sand tube while inflated,cover sanded area with patch when deflated.

Make sure glue is dry before applying patch.....If patch was installed correctly,you wouldn't be able to pull it off.

Glue should be dry to the touch....But try not to touch it.....You get 1 shot at applying patch when glue is set.

If your doing this at home,I use a pen to make a circle around the hole about the size of the patch,sand the tube good,no shiny spots,apply glue,let dry about 5 min at least,apply patch.

RubeRad

We did that; except we glued and patched while still semi-inflated -- and even then we couldn't find the hole. You can't only sand exactly the area the patch will go on. So how do you mark the hole to not lose it? Even to make sure you're sanding in the right area (just near the hole)?

yah, we probably should have let the glue dry, especially the 2nd application. But the patch wasn't merely pulled off, I had to forcibly tear it off. I've read here at BF that vulcanization does take some time; well-applied patches do stick securely within seconds, but they continue to cure over a few days or so.

Booger1

If your doing this at home,use a pen or marker.....On the road,spit and finger...

If you look real close when you add the glue,it will show you the hole.

You let the glue dry before the patch,you'll have a hard time taking it back off.

Don't know if you have ever used laminates on wood with contact cement,same thing....You get one shot,it better be in the correct position.

SBinNYC

0. Note type of hole. Indicates whether it was puncture, blowout or pinch flat.

1. Put a toothpick in the hole to mark it.
2. I use a Rema patch kit box that's plastic.
2a. Place line lengthwise on mid-way box with crayon. Does not need to be accurate
3. Take tube and place it flat on marked box. Center hole laterally side-to-side on tube. Center hole lengthwise on line. You now have a bullseye where flat is.
4. Clamp tube using clothespin or other clamp so tube won't move.
5. Remove toothpick.

6. Use sandpaper to thoroughly clean tube. Sandpaper area is larger than patch.
7. Place drop of vulcanizing solution on tube but offset from hole.
8. Use finger to spread vulcanizing solution in THIN layer on tube. Spread beyond sanded area.
9. WAIT for vulcanizing solution to dry. DON'T blow on tube to hasten drying.

10. Get proper sized patch, while waiting for solution to dry.
10a. Rema 25mm (F1) patches suitable for 28mm and wider tubes. Rema 16mm (F0) patches suitable for narrower tubes. Patch must be narrower than width of flat tube on box.
10b. For Rema patches start cellophane slit by folding patch towards foil side. Note slit direction.

11. When applied vulcanizing solution is dry, remove foil backing from patch.
12. Center patch on hole - you have 1 shot to do this. Hole is in center of tube laterally and lines up with crayon mark on box.
12a. Orient slit laterally (short dimension of tube), if using Rema patches.
13. Burnish patch on tube. I use rounded corner of 2nd Rema patch kit box. Move from patch center to outside. First box provides backing, so I'm pushing patch onto tube. Air does not make a good bond - no need to be gentle.
13a. For Rema patches look for orange layer dissolving into tube.

14. Remove tube from box.
14a. For Rema patch enlarge slit by increasing fold. Also stretch patch by holding thumbs on both sides of slit. Object is to have slit completely separate cellophane into two halves.
14b. Remove cellophane from inside center to outside. Object is to remove cellophane without lifting side of patch. Sometimes folding tube along slit will be sufficient to start removal.

15. SEARCH for and PATCH additional punctures.

16. Neutralize vulcanizing solution residue by placing talc on patched area. Dunlop patch kits had a handy applicator for this.

17. Line up patches on tube with tire/wheel. Find and remove cause of flat.

It takes more time to write this out than to do it.

Retro Grouch 

I mark the hole with a Sharpie.

RubeRad

It took me a while to understand what you were getting at here, but clamping the tube to a rigid object so that the hole remains centered wrt to the object, that's a good idea. A 4x4cm piece of cardboard or fiberboard and two clothespins or binder clips would be a good seatbag-stashable way to achieve this.

Leebo

One dot on the hole, a small 1/2" circle around it. Can see it after the sandpaper.

AnkleWork

That was a bad idea. Why not just follow known-good instructions? [shrug]

Bill Kapaun

I put a couple "dots" of whiteout, spaced just a bit wider than the patch diameter on opposite sides of the hole.
That's enough to center and align the patch.
These old eyes just don't see the Sharpie lines that well anymore, but yours may.

jyl

Vulcanizing "glue" needs to be dry or nearly so, tire needs to be deflated, mark hole w/ sharpie if you need to, make sure the edges of the patch are glued down. Easiest is to train him to swap a fresh tube when on the road, rather than patching.

RubeRad

Because if the tube is deflated, usually the hole is invisible. At least with some air I can hope to see or hear or feel where it's coming out so I can center the patch.

RubeRad

That was my concern, I'm surprised you can still see it after the sandpaper.

Although I guess, sharpie could be (re)applied between sandpaper and glue if necessary.

Number400

When you said it seemed to hold, did you pump it up a little to test the patch before putting into the tire and back on the rim? If so, that's a bad idea (it stretches the tube around the patch and it can pucker and fail). Find the hole, rough up the area, lay down the glue and wait 5 minutes, then put the patch on (hopefully in the right spot) and then squeeze it and press it and make sure it is on there good. Then immediately put into the tire and back on the rim and pump it up to %80 or so of what you normally run it. Putting it back into the tire before inflating will often make a patch adhere better, even if you put in on with a wrinkle, or if you were roadside and there was dirt/dust mixed in. If it holds at %80 for a few, then pump up to to full pressure and you are good to go!

andr0id

Actually a 1-1/2 - 2" or so dowel works great for this too. then the patch edges can be smoothed out completely.

Put a line straight down the side of the dowel.


Blow it up, mark hole with a ball point pen.

Now hold tube around the dowel with the hole over the line, sand, glue, let it dry, stick on patch, rub it down, hold a few more minutes, it's ready to go.

RubeRad

Yes. You are probably correct, that's a bad idea, but I don't know if I have enough faith to remount the tire&tube before a pump test.

RubeRad

That's an interesting concept too, although a big chunk of dowel would be less convenient to carry around than a credit-card-sized piece of cardboard (or hey, how about just use A CREDIT CARD?). Short length of PVC could work the same, and it would be easier to use clothespins to hold the tube still.

Number400

I have been there. I recently grabbed an old pinch flatted tube to put on my Wife's bike and after carefully patching both holes, I mounted it up just to hear the hiss from yet another hole. I patched that one too and all three patches are going strong!

andr0id

Carrying it around would violate the first rule of patching tubes which is: NEVER patch tubes on the side of the road, no good can come from it, only frustration.

It's best to carry spare good tubes and swap them on the road then patch at home.

I just wait til I get a handful of tubes with holes and triage and patch them while watching Netflix.

cvcman

i dont even bother patching them anymore,,,new tubes are only like 4 or 5 bucks...not worth to to me to try and patch them

RoadTire 

Silver or Gold Sharpie. All the black component on our bikes, including tubes, doesn't work for me and black sharpies. Can't see s**t either.

MichaelW

this is your mistake. You need to prep the surface again, remove all dry cement.
I mark the hole with a circle/crosshairs of sharpie after sanding.
Make sure glue is tacky rather than totally dry before applying patch
try some test areas to feel the correct level of tackyness

scroca

For some odd reason, I like having tubes with lots of patches. It's kind of like the feeling you have when you get away with something.

Who can look at a tube with six patches and not feel good about it? It always makes me smile.

RubeRad

I'm with you; I'm cheap and proud of it.

noglider 

I used to circle the hole with a pen, but I would still lose it in the glue. Now I mark it with a CROSS! The cross can be much bigger than a circle. A 12 year old gave me the idea years ago, and I am grateful for it eternally.