In any list of the top 10 repairs every bike rider should learn, fixing a flat is probably Numero Uno. And, unless you’ve embraced tubeless-tire technology, that inevitably means you’ll have to patch a tube. We’ll cover the basics here, but also check your patch kit’s instructions and defer to them where details differ.
Here are the typical steps for patching a tire tube:
This article describes how to apply a patch at home, using a traditional glue-on patch. For most flats, you can do a similar fix in the field.
Note that many patch kits now come with glue less patches—the steps are essentially the same, minus the glue application. Early generation glue less patches tended not to hold as well as glued-on patches. Today’s glue less patches have serious staying power, though their chief appeal remains that they are quicker and easier to apply.
Most patch kits include the following:
When you remove your bike’s wheel and then the tube from your tyre, look for the origin of your flat. Check the tyre’s outer surface for damage or wear—things like a thorn or piece of glass lodged in the tread, or a cut in the tread or sidewall.
If you find something, that will point you toward the tube leak. Look in that same area, checking both the tube and the inner surface of the tire for similar damage. Remove any imbedded object from the tire, and mark the location of the leak on the tube.
If no outer tyre wounds point you toward the tube leak, then check the thin strip along the inside of your rim. Look for protruding spoke ends or areas where the strip may be distorted, allowing the tube to get pinched against a spoke-hole opening.
Tube damage can be difficult to spot. If you don’t see any obvious clues, then it’s time to grab your tyre pump:
If you think the damage is too extensive to patch, then a spare tube is your fix. Any time a tube’s valve is damaged, even at the base, then it’s definitely not repairable. In a borderline case, you can try a patch and let its success or failure dictate a full tube replacement.
It’s wise to carry a spare tube when you ride. Many riders default to replacing the tube on a ride because it’s the easiest way to ensure they have a dependable fix. At the very least, you should have spares in your home repair supplies. Tube size information should be on the sidewall of your tyre; it should also be listed in your bike owner’s manual.
Some riders will use a patch as a field repair, then they replace the patched tube with a new tube at home. A patched tube can be just as dependable as a new one, as long as the patch is done well and the patched tube isn’t several years old or dappled with multiple patch jobs.
Once you’ve located the leak and decide to proceed with a patch, then it’s time to clean and scuff up the surface of the tube:
After you apply your patch, let it set for several minutes. Then add some air—but don’t fully inflate the tube because that stresses the patch before the glue has fully cured. Test the tube underwater again, checking for any bubbles coming out from the patch.
One final check: Leave the tube out overnight, too, and check the next morning to see if it’s lost any air. If not, you’re ready to insert the partially inflated tube back into the tire. Then it’s a matter of reseating the tyre onto the rim, fully inflating it and putting the wheel back on the bike.