FrenchCyclist

Hi there,


I made a nasty split in my inner tube. I have been trying to patch it, without success.

The way the split was made is the following. I rode on a nail. It pierced the inner tube from the outside, but the problem is that I walked my bike home without removing it, because I thought I had a flat tire for another reason.

The nail thus made a very small hole on the outside of the inner tube, but two large rifts on the inside.

I have tried patching both sides by making patches from an old inner tube.

The small hole on the outside got patched perfectly, but I couldn't get the inside large rifts to heal at all.

Here's what I did:

• I rubbed the area around it well with sandpaper
• I cut a patch in the old inner tube, trying to make beveled edges with a box cutter
• I sanded the patch well, and sanded particularly well the edges, to try to make them thinner
• I cleaned both surfaces
• I applied rubber cement from a Zefal kit on both surfaces
• I let it dry for 5 minutes, as indicated on the Zefal kit's manual
• I applied the patch, pushed well on it with the tire removal tool
• I stepped on it for 2 minutes
• I reseated the inner tube, pumped it lightly so that it would press against the tire edges
• I waited till next morning

In some cases, the inner tube would still be inflated on the next day. I would then pump it to 3 bars, but then it would deflate within less than half an hour, without using the bike.

Alternatively, I also tried pumping directly to 3 bars right after stepping on the applied patch, but it wouldn't hold at all.

Sometimes, after deflating, I would take the inner tube out, submerge it in water, pump it a little, and it wouldn't leak at all. Surprisingly, I would have to reseat it and pump it to 3 bars for it to deflate again.

I tried some variants, for example smoothing the glue layer with my finger before letting it dry, no change. I also tried letting it dry for 15 minutes, no change. I also initially tried to just cut the patch without beveling the edges, no change.

I've been failing for about 10 times in a row now.

Each time it's pretty easy to peel the patch off, most of the time it even remains in one piece.

Could it be because I am making these patches myself? Would the result be any different with a bought patch?

Could it be because there might be remains of glue from my first and subsequent attempts, that prevent the patch from adhering well?

Any idea what I might be doing wrong, or how to fix my inner tube?

I am trying to upload pictures but the forum won't let me, you can check them out at drive <dot> google <dot> com/drive/folders/1ZUAiv8zLEL8nRBpdpWs4Qkd-F_1HX3YD.

Thanks a lot in advance for the help!

Kontact

Don't pump it up at all. Let it sit overnight.

The problem here is that you likely have a smallish tube volume, so when you air it up the patched area and surrounding tube stretch at different rates, which act like peeling tape off something at an angle. If the patch is large enough and the bond good enough, you may be able to inflate the tube without the bond failing all the way back to the tear.

Using the thinnest possible innertube as a patch will also help to minimize that difference in stretching.


Obviously, you could also just replace the tube. But it is an interesting problem.

Iride01 

I usually wouldn't try to repair a split or tear. Unless we are only talking a couple millimeters.

In fact, since I rarely ever get a flat, I just put in a new tube, even for a puncture.


Welcome to BF!

crn3371

Use actual patches, not homemade. Throw that tube away and get a new one.

FBinNY 

Yes, tubes are too cheap to dabble in unreliable complicated repairs. Patching simple punctures makes sense, but you need to be willing to quit.

Also, buy and use a proper patch kit. Patches use a 2 part bonding agent. Half is in the "glue" in the tube, and half on the prepared patch. While homemade patches can seem to work, they won't be as reliable.

HillRider

That was an awful lot of time and effort to save a $3 inner tube. I will patch a small thorn or wire puncture if it isn't on a molded seam or too near the valve base but any wider cut gets the tube pitched.

zandoval 

Your method and application appears sound but it did not work. Oh, Well...

Sure sounds like a problem with dissimilar materials in the components. Or a common failing of newer vulcanizing cement that does not contain Toluene. Toluene is a vital component of having a good bond in vulcanization. Of course like many things it has been found to be carcinogenic and therefore is on the Stigma List.

In my flat fix kit I keep a small tube of unopened Vulcanizing Cement and an unopened Tube of Super-Glue just in case the Cement has dried out.

Further note that over the years, although some people have, I have never had a successful seam rip repair on butyl tubes.

tFUnK

Inner tubes haven't been $3 in quite some years now. But I agree it's a lot of effort to save a tube. My rule is 2 attempts before I give up. I'm just as diligent as the OP but sometimes luck is just not on your side.

Crankycrank

I have made many attempts over the decades to make patches with old inner tube rubber and the results were iffy at best with too much time spent trying to make them work. Go for some Rema brand patches.

maddog34

tubes now cost $4 each if you buy 6 at once... $7 each as singles.... And that is for the cheapest ones. I won't buy the cheapest ones, too many seam splits and valve problems.

your pricing may vary by season and if you buy from a bicycle shop....

RCMoeur

I patch several hundred tubes a year for four different nonprofits. Doing it in bulk saves a lot of money for these organizations with now that wholesale tube prices are up above $5 each.

I agree that proper surface prep and the correct tools & parts are very important for success. When working in bulk, I use a battery powered dremel with a sanding drum to get a clean roughened patch area (going 20-40% larger to be safe) in seconds, with all bumps, seams, and ridges obliterated. Now this isn't typically an option on tour (the tool doesn't weigh much at all, but it's bulky), but for shop or home patching it's a huge timesaver & greatly improves the likelihood for success.

I also only use genuine Rema cement and typically use only Rema patches. I've tried off-brand cement & patches with much lower success rates, as the cheap cements just don't create as good a bond and can stay "not set" for a while, allowing peel-off. I have successfully used non-Rema patches with Rema cement when a Rema patch won't cover the hole properly, but I prefer the Tip Top whenever practical. I've encountered tubes patched with old butyl tube casing instead of a patch, and all too often it's an easy task to peel that patch away with bare fingers, let alone what air pressure can do with much greater force.

All this being said, patching a slit or tear is tough even when the prep, patch, and cement are exactly right - the tube still really wants to continue separating along that plane of weakness. Sometimes it holds together great with a good Rema oval patch... and sometimes it doesn't. The only patch locations with lower success rates are ones where the hole is less than 1/2 patch diameter away from the valve.

cyccommute 

The only critique I have is with using non-Rema patches with Rema vulcanizing fluid. There is no reason to do that. Rema patches need Rema vulcanizing fluid to make the patch. It’s a two component system that works when both components are there. When one component is missing…like using non-Rema patches…you might as well be using rubber cement which is cheaper. Not as good, but cheaper.

cyccommute 

Photo assist







It looks a bit like the tube is past its prime. Patching it with anything is going to be dicey.

That said, go buy some Rema TipTop patches. They are cheap. Amazon has a kit for less than $3 each. Buy a couple or more. Your time is worth something and life is too short to try and reinvent something that already exists. Chemists use something called the Donem Principle which states “if someone has already done ‘em, don’t do it again”.

Bill Kapaun

I've ran into a couple bicycle tubes that seemed like that. Kind of like it was part vinyl ???? (also a friend's wheelbarrow tube from a China-mart)
My REMA patches just peeled off instead of fusing. Ditto for a vinyl patch. (air mattress) IIRC, they took about the same effort to peel.

RCMoeur

I suppose I could have been clearer - if a Rema patch will work, I use a Rema patch (small, standard, or oval - I buy them in the 100-count boxes). I only use large off-brand patches if the hole or blowout is too big for any Rema I have. And with proper prep and Rema cement, I've had decent success - not as completely reliable as Rema, but a good enough success ratio to justify doing it where there's no other option.

RCMoeur

Those are sometimes a challenge. With thorough surface roughening and Rema cement, I've been able to get a Rema patch to stay permanently. But they can be tricky.

maddog34

dude.. buy a new tube and admit that you ruined a tube. That thing is thrashed. a large area has been softened by the repeated chemical attacks on the material. wow.

and order a decent patch kit too. Remo and Park work fine. Quit spending HOURS to only find that you've ruined what you tried to salvage.

and a "patch" that big will make flat spot on the tire due to that double-thick area NOT STRETCHING when you inflate the tire/tube.... if it had held..

seriously.

the "holes" on the opposite side look like Tire Iron Marks, for the record... AKA: "Pinch Flat"

tFUnK

Lately I've been doing this instead of traditional patches. Seems to hold up pretty well.
​​​​​​ Working great so far on TPU tubes; time will tell how well they hold up on butyl tubes.

Racing Dan

Im sure you were already told, But

-cutting patches from old innertubes just doesn't work.-

Get at patch kit and follow the instructions. Especially the part about letting the solvent in the glue evaporate for 5 minutes before applying the patch, and you be fine.

JohnDThompson 

And use the Rema cold-vulcanizing fluid, not rubber cement. As @FBinNY noted above, an effective patch is a two-part process involving a chemical reaction between the tube, the patch, and the vulcanizing fluid.

cyccommute 

That sounds like the tube was a thermoplastic polyurethane or TPU tube. Rema cold vulcanizing patches aren’t going to work on those nor would rubber cement. Different chemistry.

maddog34

pretty sure those are the tubes i've seen seam-split when first aired up, too.. and one had the stem blow out.

they feel rather greasy and slippery to the touch.... at first i thought the feel was due to a new release agent during Mfg. but then i tried patching one... that was a waste of two good patches!