Life from an outsider's perspective…

How to patch an inner tube the right way.

The definitive guide to repairing a bicycle inner tube with a patch kit.A lot of people don’t patch bicycle inner tubes anymore, which I think is a little bit sad. Generally speaking, it’s better for the environment to repair rather than replace, so that’s reason enough for me to continue patching tubes. I am sure that the sale of a small patch kit along with extra patches more than offsets the environmental cost of yet another replacement innertube.

I have a strong hunch that most people who buy new tubes all the time do so partly because they don’t know the correct procedure to use when patching an innertube. Maybe what happened was that like me they tried to repair a tube when they were a kid & failed miserably. I’ll admit that despite 10 years of biking experience, I never really bothered with patching tubes until fairly recently either. It’s not that I lack time – it’s that they’ve never worked for me in the past, because no one taught me the proper technique. I have had limited success with glueless patches (park ones are the best by the way). But if you follow this detailed guide, you can repair your punctured bicycle tubes the old fashioned way (using glue and patches) so they behave just like new.

Before I get started, why did I suddenly become converted? Well, what happened was, I got one of my hire bikes back, and to my surprise, one of my clients had patched one of my butyl inner tubes that had punctured. It was the most amazing patch-job I’d ever seen! The edges of the patch were *completely* flat. This one paticular cyclist had reached what I’d call “punture repair perfection”. It was even better than those glueless patches I tell you. So ever since then, I reaslied it could work. After a fair amount of trial and error, I eventually found the right way to repair tubes using the traditional glue & patch method – I’m convinced that nothing beats it.

  • For the best inner tube repair, it’s best to wait until you get home. This is why you should always have at least one spare inner tube handy when you go on a ride.
  • Wash your hands. I don’t know about you, but whenever I’m in my workshop my hands & fingers are covered in dirt and grease.
  • Get all the air out of the tube. The aim is to get the inner tube as flat as possible. Suck on that valve if you have to (that’s also the best way to get inner tubes to fold up into a tiny package by the way)! Repairing tubes with air still in them is not the best way to do it… the patch usually crumples when the air is out.
  • Roughen the area with wet/dry paper. 320-600 grit is best. Too fine and you won’t abrade the surface enough, leading to adhesion problems. To course and you’ll scratch the tube, weakening it.
  • Clean the whole area of the tube with isopropyl alcohol (Isocol) to get the butyl rubber residue off. If you can’t get hold of that, use methylated spirits instead.
  • Most people use waaaaay too much glue. A rough guide is that one of those tiny tubes of rubber cement should last about 30-50 patches (depending on the size of the patch). If you are prone to getting punctures, and you’re repairing enough tubes correctly, you’ll end up with a major surplus of glue. To give you some idea, start with an amount equal to the size of a split pea.
  • Smear it over an area larger than the patch itself using your pinky finger (cause it’s always the cleanest one). This is easily the most critical step, so pay attention here. Apply 1-3 THIN coats of glue to the tube in this manner, and another THIN coat or two to the patch itself. Always wait until the glue is dry before applying another coat. Try and achieve the thinnest possible coats of glue, and you won’t have to bother waiting about the drying times involved. You’ll know if it’s thin enough, cause it’ll start to become tacky during the smearing operation. When you can feel the glue starting to become tacky, stop smearing.
  • If the layer of glue still looks wet after a few minutes then the coating is way too thick; it’s better at this stage to keep smearing it over a larger area until it’s thinner. A good way to check the thickness of your glue application if you’re not sure: if it becomes all misty & fogged up when you blow on it & the fog doesn’t disappear for a while, then it is too thick – so you need to wait for it to dry. Remember to apply less glue next time.
  • Be sure to evenly cover the entire surface of the patch, taking care not to omit the edge zones. Done that way, the patch should stick to the tube almost instantly. Having said that, resist the temptation to stick the two together.
  • Let the glue partially dry. Partially means just that – partially. If you wait too long, the glue will dry, it’ll get dusty and the thing will never bloody stick right. Too wet and it the patch will slide around and you won’t get good adhesion due to all the movement. You’re linking molecules together here, so this step is just as important as the others, if not the most.
  • Don’t touch either the glue or the patch when it’s drying, otherwise you’ll contaminate it. Contamination = weaker bonding.
  • Press the two surfaces together with considerable vertical force and zero horizontal movement. Time for an analogy. Think of the scale. From the perspective of a tiny molecule or atom (~nanometre size), one millimetre of lateral movement is equivalent to ~2000km for you and I (depending on how tall you are). How the hell can billions of people (atoms) hold hands (link together) if they’re flying past eachother at 7.2 million km/hr? Molecules move around and vibrate enough as it is without amplifying the problem further. So aim to keep everything still! If it slides around, you either haven’t let the glue dry enough, or most likely, you’re using too much glue in the first place. For the best results, put the inner tube onto the corner of a table & once it’s totally flat, place a heavy flat object on top.
  • Patience is the key to a perfect union between humble patch and bicycle inner tube. Let it sit as long as you can to permit those interlinked chemical bonds to form. At least 10 minutes is good. 30-60 minutes is better. Overnight is best. I know, I know, you’re eager to check and see how it went. That’s understandable. But if you don’t let the glue dry properly, you’ll botch the whole operation.
  • How do you know if you have done it well? There’s one simple final test: very carefully peel back the thin clear plastic layer. This is one task that all cyclists hate to do, because 9 times out of 10 one corner of the patch starts to peel off along with the protective plastic. Yes you can try to press it back with your thumb, but once it lifts, there’s no hope for a perfect patch prize mate. If you’ve followed the method I reccommend here, to the letter, this won’t happen.
  • Remember that all steps are equally important.

There are several “patching a tube” tutorial videos floating around the internet and I’ve watched a few of them. One of the better videos can be seen on www.bicycletutor.com. I can tell that this guy never bothers to patch tubes because he doesn’t know what he’s doing. You can see that his patch doesn’t even stick! Why don’t people actually video the entire process including removing the clear plastic film (the most crucial step to determine if you’ve made a good job of it)? Because the corners of the patch will peel, revealing their flawed methods, that’s why. If you look at his video, the patch simply is not sticking. Here is yet another video attempt to patch a BMX inner tube. 10 points for this spur of the moment effort. No one apart from this young man actually goes to the effort of fixing a real punctured tube either.

10 Responses to “How to patch an inner tube the right way.”

  1. Good job describing how to reach ‘Patch Zen’

  2. Thanks! This guide definitely helped. It may also be helpful to note that one should peel off the aluminum from the patch (leaving the plastic), then coat the tire and patch with a bit of glue, and after mostly drying, stick together.

    Most of that was covered, but the part with peeling off the aluminum while leaving the plastic was left out.

  3. Excellent description. My dad was a patch master. When we kids would get a flat riding around the house, he’d patch it, and within an hour would be riding again. The patches never gave out and the corners didn’t lift up on them either. My dad even had the really old kind of patches that sit on top of a metal casing that held a material that burned. If we were out of the modern patches, he’d use one of them. After clamping the metal cartdidge onto the tube, he lit the material and let the thing burn heating the patch and bonding it to the tube.

    Lately, I’ve been wishing I had paid more attention to how my dad patched his tubes. So I really appreciate this post and look forward to applying the technique to my own inner tubes.

  4. this was really helpful and it worked fine thank you whoever made this. my bike is running again.

  5. I just wanted to drop you a note thanking you for the blog post about repairing inner tubes. I recently had a generator cart tire failure, and the inner tube was not locally available. Of course, the cart was ABSOLUTELY needed the next day. To make matters worse, the tube
    failure was not a simple puncture, but rather the rubber around the valve stem base had broken down. I thought I would have to lift the 700 lb. generator off the cart, and then manoeuvre it onto a trailer.
    But I had a couple of old (different size) inner tubes with the same angled stem, and as luck would have it, one of the valve circles was mostly separated from the tube. With nothing to lose, I shaved down the remaining stem rubber, made a fixture to slip over the stem and followed your procedure. After a couple of hours I came back and checked the patch. Success!

    So, thank you sir!

    Doug Herring

  6. A hair dryer will help heat things up and heat always enhances chemical action and that’s what patching is all about, getting the patch to bond with the tire. I heat the tube right after scuffing the leak area and include the patch.

  7. When I was younger (only 35 years ago), a new inner tube was a major investment. Punctures had to be fixed on the side of the road, and were so common that I had a 6″ square of “patch” rubber and some scissors to cut a piece the right size – plus some rubber solution to stick them on with and some French chalk to grate over the area to stop the rubber solution sticking to the tyre. Actually, I still do it this way but with pre-made individual patches with chamfered edges. They’re are better than the old ones. Modern tyres are also a lot more thorn-proof!

    The point is that you don’t need to be so prissy about bunging on a patch. None of mine blew using the cruder methods by the side of the road. It has the advantage that you don’t always need to remove the wheel/tyre – just pull out the section of tube if the source of the puncture is obvious (e.g. a nail or thorn).

    One thing no one as mentioned is the need to identify the source of the puncture of the tyre itself. If the thorn is still there you’ll get a new puncture as soon as you put the tube back! Obvious, but possible to overlook unless you’ve done it yourself.

    I suspect the reason a lot of “crude” patches don’t work is that people inflate the tube OUTSIDE the tyre. Inside the tyre the pressure keeps the patch firmly in place against the inside of the tyre, and limits the stretch of the tube. Using modern patches your tube was be “as good as new”, but inflating just the tube with unchamfered patches imperfectly applied will cause the underlying rubber to stretch and the patch to part company. Resist the temptation! This might be why people reckon patching is difficult.

    These days I normally swap the tube and fix it at the end of the day – marginally quicker when you’re on the road. I carry a spare tube anyway because occasionally you get the kind of puncture that there’s no coming back from!

    This brings me back to the question, why am I reading this blog? I was hoping to find someone who knew how to fix a valve back if it’s been ripped out of the tube. I wouldn’t normally bother, but this is 14″ wheel and I need to get the bike on the road NOW and don’t have a spare :-(

  8. Thanks for this excellent tutorial, I am practising your method now. Putting glue on the patch was a revelation to me,. It really works better. I look forward to creating patch perfection in the future.

  9. Thanks for this article. After patching inner tube for my road bike, it inflates unevenly (fat bits, thin bits). It seems that the patch is pinching the inner tube. Is this normal?

  10. I followed some tutorial videos on Youtube, and they all suck! After I applied your technique I successfully fixed the puncture on my tire and rode my bike to school.

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