Bike Tube Repair





Introduction: Bike Tube Repair

About: I'm an Italian freelance structural engineer, graphic designer and photographer, and I'm teaching physics in Waldorf schools. I always investigate electronics, robotics and science in general, I'm a passiona...

Repairing a bike inner tube is not only simple and cheap, but it's also mandatory in respect for the environment. Indeed a punctured tube can be repaired many times before being thrown out. A different matter is when the tube is cut or the valve leaks, since it's more difficult repair the tube. Anyway most of the times the leak is caused by a nail or a thorn, and the hole is very tiny.
Although many of you already know this process, I'll explain how to easy add a patch to a pierced bike inner tube.

Step 1: The Necessary

All you need is a pump and a repairing kit. I take for granted you already know how to remove the wheel from the bike and the tube from the wheel, so I don't deal this topic here, ask in comments if you fall in some obstacle.
The repairing kit is composed by some patches (probably of different sizes), some scratch tools (sandpaper or a little metal grater), a little tube of mastic (a type of glue) and maybe some little rubber tubes to spread mastic.

Step 2: Inflate

First thing to do: find the hole. This could be simple or pretty long. If you're lucky the hole is big enough to listening the air flowing out when you inflate the tube. But many times the hole is so tiny that air comes out very slow and it's difficult to find, in this case go to next step.

Step 3: Blblblbbl

To find the tiny holes inflate the tube. Don't be scared to inflate the tube very much, it could also become double in dimensions without exploding, and this will help you find the hole, since some hole remain closed with low pressure. At this time dip the tube into water, a sector at a time, until you see the bubbles coming out.

Step 4: Mark

Mark the hole with a permanent marker, so you will not have to make the entire process a second time if you look away for an instant ;-)
Make the mark twice as big as the patch with an "X" through the center of the hole, it allows for spreading out glue if too much is applied.

Step 5: Scratch

With the help of sandpaper or grater scratch the rubber all around the hole, this will help the mastic to adhere to the tube. No reason to wash away the rubber powder when finished, just blow it away or clean with your hand.

Step 6: Mastic

Time to spread the right amount of mastic on a surface a little wider than the patch. Move the head of the mastic container from center to the border, as pizza maker does with the tomato sauce. 
Use a thin layer of glue. More isn't better and if it is cold will take much longer to cure. If too much comes out use the small rubber tubes in the repairing kit to spread it out.
The mastic will now dry in a few minutes. About 10 minutes will be probably a good time to wait before attaching the patch.
Don't touch the area that has been roughed up. Oil from your hand will contaminate the surface and impact glue adhesion.

Step 7: Patch

The patches have a metal cover on the glue side, and a plastic foil on the other one. When you remove the metal cover, the plastic transparent sheet should remain in place, you'll remove it after the gluing process.
Push the patch very hard over the dry mastic, you should use now an hard tool to make pressure, as the back of the pump. The more pressure you apply the more efficient the fixing will be.

Step 8: Strip

To remove the thin plastic sheet you have to keep down the patch red border with your nail. It's not a big problem if the border detaches, anyway try to leave it glued. If the plastic layer won't release from the top of the patch, leave it be, when 60+ psi push it against the inside of the tire, it isn't going to make any difference.
Now you could in theory assemble the tube on the wheel, inflate it and ride. So don't be afraid to do that, BUT...
Remember to check both the inside of the tire and the tube protector strip on the rim for what caused the hole! If you miss that step you'll probably incur in the same identical accident for the same reasons.

Step 9: Inflate Again

Otherwise this is probably your reserve tube, you are at home fixing it meanwhile you relax your limbs after an hard riding morning, and you can wait some more time before inflating the tube to check the good air detaining. Let's say ten minutes...
Inflate a lot the tube and hang it somewhere in your haven, if it's still inflated the next day your reparation is perfect, if not restart from step two ;-) Obviously you can test the tube into water right away.

Step 10: Deflate and Roll Up

Now deflate (this is the tedious part), roll up the tube and hold it with an elastic. If you predict to not use it in a few time, you probably should scatter it with talcum powder, so the rubber will last much more time.
Also pay attention keeping your reserve tubes in the little bag under the saddle, because continual rubbing can wear out the borders. A solution is to put the tube in an old sock, which makes a great rag and you can put it on your hand if you need to swing a derailleur out of the way to remove the rear wheel.
And remember, always bring at least a reserve inner tube with you, among with the necessary to change it, and to be safe bring also a repairing kit, it happens to get three or more blowouts in the same trip! I'm not speaking about city cycling ;-)



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    FYI: In the course of some reading/research, I found many comments on the reason for the thin plastic strip on the top of the patch. Many of which made no sense. I ended up calling the TEMA Tip Top patch company and speaking the product engineer. Common question (makes me wonder why the answer isn't on their web site) and the answer is: Nothing to do with using the patch. It's residue from the manufacturing process and they just leave it on. I assume that's cheaper than trying to remove it, and it does provide a small layer of protection over the patch.

    One more hint: Use the abrasion pad to mark the hole. And I've found the more complete the abrasion, the better the glue will stick to the inner-tube. The latest Tip Top patch kits stipulate that after putting on the patch, no pressure period is required.

    1 reply

    Woow that's interesting, specially the info about the thin transparent layer! Thanks!

    Nice! I teach basic bicycle maintenance at a bicycle coop including hands on tube patching. I use a kit that has instructions to show students the benefit of reading them (former aircraft mechanic where everything was done by the book). To your great 'struable I would like to offer: 
    • Make the mark of the hole twice as big as the patch with an "X" through the center of the hole. Allows for spreading out glue if too much is applied.
    • Don't touch the area that has been roughed up. Oil from your hand will contaminate the surface and impact glue adhesion. 
    • Use a thin layer of glue. More isn't better and if it is cold will take much longer to cure. If too much gets glopped on (technical term :-) ) use the end of the tube to spread it out.
    • If the thin plastic won't release from the top of the patch, leave it be. When 60+ psi push it against the inside of the tire, it isn't going to make any difference.
    • Don't forget to check both the inside of the tire and the tube protector strip on the rim for what caused the hole.
    6 replies

    Meant to add a suggestion I read but can't remember where:
    Put the tube in an old sock. Makes a great rag and you can put it on your hand if you need to swing a derailleur out of the way to remove the rear wheel.

    Carbon copied to the ible this tip too ;-)

    Hey, discovered something to add to this. A lot of patch kits come with a VERY small tube of glue that just won't do all the patches included. Well, turns out that if you heat the patch while it's on, the orange part will melt and adhere to the tube even better than with the glue alone. Throwback from when patch kits included a box of matches for vulcanising, I guess. Anyway, by running a lighter gently over the patch then pressing down hard, I got a better bond than by glue alone and needed just a tiny drop to hold the patch in place. I even experimented with NO glue - just the heat method. The tube is still holding air perfectly, so if you're stuck for glue, find a smoker!

    I'm glad you found my suggestions helpful. Looking forward to your next posting.

    that's very useful and funny :-)

    Ouch!! I FORGOT to mention to check the inner of the tire!! Thanks for remembering me that! It's extremely important!
    I agree with all your notes and I'll take the opportunity to add them into my instructable. Thanks again.

    Great 'ible. May i add that you can detect a leak not only by sound but also by rotating the tube past your nose or corner of the eye, more sensitive to a tiny squirt of air. I've also found it helps the patch stick if you spread the newly patched spot out on a hard surface, then tap it with a hammer, staccato like. My biggest woe has been unreliable or stale glue, so i inflate the repaired tube and let it stand overnight to ensure that the patch bonded.

    Don't forget to rub the little block of chalk on the sandpaper over the repair and rub the chalk dust into the excess glue areas around the patch. This stops the tube potentially sticking to the tyre.....

    1 reply

    Well explained and well illustrated! It's been a long time since I've patched a tire, but surely my luck will run out eventually. Thanks, Andrea!

    One question, though: when I was a kid it was common to light the adhesive with a match before applying the patch. What was that about? Do people still do that?

    5 replies

    ... Back in the ' Day ', we used to light the glue on the patch to pre-cure or ' vulcanize ' it. They are now self-vulcanizing and need no fire ...

    At the bike COOP where I teach basic maintenance, including a hands on tube patch), I offer this opinion:
    Chemical engineers are paid a lot to create the adhesive at the lowest cost. I doubt burning off the violates is part of their product engineering or else it would be in the directions. Better, IMHO, to follow the directions.

    Also, I suspect some confused the old Camel and Victor hot patches that were lit on fire with glue on patches.

    As I remember, the instructions said something to the effect of ' Apply glue to patch, let the glue dry until tacky ( allowing the VOCs ( Volatile Organic Compounds ) to evaporate ), apply to prepared tube over puncture, apply pressure to seal .
    An older person than I, would set fire to the glue on the patch to speed up the evaporation of aforementioned VOCs. I assume they currently use a faster ' flashing ( evaporation of VOCs ) ' adhesive.

    We always lit the glue even though they were supposed to be OK done cold. I still use the same process when patching the tubes on my motorcycles. No sense in buying a new tube if a simple repair can do the job.

    I don't know... I've to ask to my father... how old are you, uncle? ;-)