This post explains how to patch a bicycle tube. If needed, read posts on how to remove wheels and how to take tyres off and tubes out. Finally, here’s a post explaining mounting tyres and tubes onto a rim.
1. Inflate (removed) tube to see where the puncture is
If a puncture can’t be located visually – very small leaks that can’t be heard, or felt with fingers, try using water:
Place (or several places) where the puncture is found should be marked:
2. Determining the cause of puncture(s)
Before patching a tube, a cause of flat should be determined and fixed.
If a tube has two parallel holes (cuts) at a small distance, then it is a pinch flat, also called a snakebite. It happens when a tyre is not inflated enough. When a wheel hits a bump, the tube gets pinched against the rim and gets cut.
b) Rim/spoke damage
If there is a hole on the inner part of the tube, the one towards the rim, then rim needs to be checked for sharp objects, or sharp parts of a damaged rim. Also, rim tape needs to be checked – is it undamaged, is it placed correctly. In case of double walled rims, make sure the rim tape is a good quality high pressure one. All explained in this article:
Rim tape types.
If a cut is near the valve, the tube can not be patched.
c) Hole in the outer, or side part of the tube
Probably from some sharp object – thorn, or glass. Carefully examine the outer tyre, make sure the sharp object is not still in the tyre – to cause another puncture. Turn the outer tyre inside out and examine carefully. Slide some fabric along the inside of the tyre, or fingers, but be careful not to cut your hands.
D) Long cut in the tube
If a tube has a large cut, or a blowout like a balloon , then it can not be patched.
This can be caused by poor tube quality, but more often it is due to outer tyre casing failure, or improper mounting of tyre and/or tube. This can also happen if rims overheat from long braking (if rim brakes are used). Pressure rises with great heat, outer tube gets off the rim from over inflation of the tube and then tube bursts.
If a tyre wall is cut like in the picture above, tube often explodes. This is caused either by poor tyre quality, or by a large sharp rock.
Tyre can be patched to get home, but needs replacing as soon as possible.
Tyre can be patched either with special tyre patches, or with a piece of hard card board, or with a dollar bill, or a part cut from another (old) tyre, but not the tube! Do not use a piece of tube to patch cut tyre, since it is not firm enough to hold pressure.
Affiliate link of an Amazon.com search for the (as an Amazon Associate I earn from qualifying purchases): Special tyre patch boot (Park Tool TB-2 emergency tyre boot). It is a good “first aid” patch, enabling one to get home and replace the cut tyre. It is not a permanent(ly safe) solution!
3. Patching a tube
First tube needs to be treated with sand paper around the hole. Place where a patch is glued needs to be totally flat, dry, clean. Especially if it is near a tube seam.
Then add patching glue. Use the cleanest finger to nicely and evenly spread the glue.
Wait five minutes for glue to dry.
Place a patch. Press firmly, to make sure no air is left trapped.
It is best to leave the patched tube to dry completely over night. That is why it is wise to carry a spare tube. Patched tube is packed in a bag, while the spare one is used to continue riding. This way, the same three tubes can be rotated for decades. 🙂
Author’s recommendation for tube patching are Rema (“Tip-Top”) glue and patches. Click on the image below to shop on-line at Amazon.com (as an Amazon Associate I earn from qualifying purchases):