You got a flat tire, probably on the trail, you put in a new tube and finished your day. Now what? Are you gonna throw that tube out or are you gonna fix it?
Learn how and why about tube repair with the right tips to do it well.
Have you ever patch a tube? Or do you just replace it with a new one?
In this article we discuss, why, when, and how being able to repair a tube is an important skill to master when you venture far from the beaten path.
Why knowing how to patch a tube is an important skill
Let's face it, the break down most likely to happen when riding any bikes and even more so a DR650 ;-) is getting a flat tire. As we all know that this bike is not orange and isn't a Known Teutonic Mistake!
Let's assume you are comfortable to take your tires off the wheels to access the tubes when you have a flat. If you aren't already, it's time to practice!
As most people do, we encourage you to carry at least the front 21" tube with you at all times.
The front tube can also be used in a pinch for the back before putting the proper 17" when you can get one, either back at home or further down the road.
But what if you don't have any tubes or if you want to go light an save space or simply take an extra 20min for repair? Then you could simply fix the tube on the trail with a few grams of gear.
And even back home, fixing the tube will save you money or make you more independent on a long journey.
Most of the time, you can repair it easily to make it as good as new.
That's right when properly done, a patched tube is as strong as new. It can be repaired multiple times too!
When NOT to patch a tube
As long as the puncture is fairly small (you can cover it with your largest patch), you can fix it. But for anything that looks like a long cut (tube failing at the seams or a cut & dragged situation) or is damaged close or at the valve stem, you should replace it.
It's not worth taking the risk of a repair that won't hold. Any torn valve stem and really big cuts will need a new tube. The same goes if the tube is getting old, with obvious marks of chaffing or the rubber isn't really elastic anymore.
A few grams of gear that goes a long way!
What is actually happening when you patch a tube? This will help understand the critical steps when doing the repair.
All rubber products like tires and tubes are made from the sap of the hevea tree, which is a gooey liquid. To obtain the black "hard" rubber that we know, it goes through a chemical reaction with heat and various chemicals/additives, called "hot vulcanization".
The "cement" used in tire tube patch kits actually (de)vulcanizes the rubber in the patch and the tube. It's sometimes called "cold vulcanization".
Which is a chemical process, usually using sulfur, where the rubber forms a stronger bond than just an adhesive would do.
It's causing the reverse reaction of "melting" the hard rubber into a more gooey state so the patch and tube can truly bond together at the molecular level.
Once those chemicals are consumed, both rubber pieces harden back together.
Good as new!
Here is the tutorial to patch a tube the right way
Tools and supplies needed
Clean rag and alcohol isopropyl (optional)
A piece of sandpaper and/or a file
Valve core remover tool
Vulcanizing rubber cement
Correct sized tire patch
A small wrench or other blunt-tipped tool
Talc powder (optional)
Note: You really need the proper "tube patch rubber cement" which has the property to start that "cold vulcanization" reaction.
Even though it can be called the same, DO NOT USE office supplies/hardware store" rubber cement or your repair will not last at all!
Available in the store: Patch Repairs Rubber Solution
About tire patch kits, any type will do!
Whether advertised for bicycles, ATV or motorcycles, only the size and shapes of the patches will changes.
Choose accordingly a good sizes spread and we recommend the one with the orange/red rim rather than the all-black one. These have a tapered edge making a better repair.
The process is easy but where most people fail is not prepping enough the tube and not waiting enough at the right moment.
Step 1: Prepare the tube
Start by inflating the tube so it can hold its shape and then clean from any debris, dust, or sand with a wet rag.
If the hole is not easy to find by looking/listening to the air hissing out, rotate the tube in a bucket of water to spot the bubbles.
Once you have located the puncture, you could eventually circle it with a permanent marker if it is really hard to see.
Then, remove the valve core and lay the punctured area flat on your knee to scrub it with a clean rag and alcohol if available.
This will help to remove the shinny aspect of the rubber from talc powder.
Now, using a file and a small piece of
sandpaper, the goal is to expose raw rubber (mate aspect) all around the hole. This area should be a bit larger than the patch you will use.
If the patch goes over some of the ridges left from the mold, it is especially important to remove those.
You need a perfectly flat surface for the entire patch area.
Step 2: Glue that patch on
Once the tube is prep, you have done most of the hard work!
Now is just a matter not rushing the gluing process.
Open your rubber cement tube and spread a good layer over the area, once again going a bit larger than the patch itself. Spread some as well on the entire patch itself.
Note: Once open, those tubes caps do not seal very well and they will inevitably start to dry over time. For what they cost, we highly suggest you keep the open one for shop use and pack a brand new unopen one into your trail kit.
Available in the store: Patch Repairs Rubber Solution
The trick for a good vulcanizing reaction is now to wait a few minutes for the rubber cement to "dry".
Tip: Do the finger test! Wait until it's no longer gooey and sticking to you finger but still tacky. You can see a shiny gooey fresh appearance in the first picture and a more mat looking in the second one.
Now you can apply the patch, starting with the center, especially on larger on, and press it nicely against the tube.
Step 3: Work it in
Once the patch is on, keep some tension on the tube, trying to stretch it a bit and use the round end of the wrench to press the patch going from center to outer edge.
You can use any blunt tip to do that, any smaller size wrench works well.
The goal here is to push out any possible air bubbles and press the whole area of the patch.
Do that for a minute and you should see the plastic film starting to peel off naturally from the patch.
You could now remove the plastic carefully, watching not to peel off the edge.
NOTE: Some people would just leave the plastic and that fine too. We rather take it off and finish to press the patch edge really well without it.
Step 4: Finish the tube for storage or re-install
The time for the patch to fully dry out can vary a lot depending on the weather.
The solvent in the rubber cement being extremely volatile, it could be fully cured in hot weather by the time you are done working the patch or it could take 10 more minutes on a cold day.
If you are doing the repair on the trail and need to reuse the tube right away, you could simply go about it without waiting. Just inflate the tube a little like you would to re-install in the tire.
Unless you are extremely fast at popping tire in, the time it will take to do it will be at least 5/10min which is plenty for the patch to fully cured!
Once your wheel is together, you can inflate it right away and control check for leaks.
If you are putting it away for storage, it's always better to sprinkle and massage some talc powder on the tube to protect the rubber sticking together and chafing in the tire.
Best way to fold a tube is to lay it flat by the centerline (without the valve core) with the valve stem at one end. Then fold in 3 parts as you push the air out.
Then, re-install the valve core while keeping the tube pressed together.
This will make it really flat and it won't self-inflate. Additionally, pack the tube in a plastic bag or even better, a vacuum-sealed bag and it's good to go back in your trail kit!
When I worked at a tire shop, 80 grit sandpaper was our go to for cleaning the tube. Use some more alcohol or acetone as cleaner after this step to wash away the shavings.