from Rookie’s keyboard,
Hello, friends
It’s time for a Friday evening post.
I’ll address a common myth that some rookies might have bought – namely the idea of patching an inner tube with cyanoacrylate glue (CA) glue (the quick type of glue available in most convenience stores).
In short, don’t do it unless there’s a zombie apocalypse.
Why? It’s inflexible and brittle upon drying. And a patch based on CA/super glue is very likely to fail.

The Inner Tube Needs Flexibility
The inner tube is constantly changing its shape during riding. Therefore, it’s of high importance to preserve its original flexibility when patching it.
CA glue doesn’t provide that option because it forms a hard layer.
Over time, the adhesive experiences “micro-shattering”, and the bond disintegrates.
Rubber Cement Is The King For a Reason

Rubber cement consists of two primary ingredients – elastic polymers (rubber) and a volatile solvent that can quickly dry in all weather conditions. The solvent keeps the elastic polymer fluid before use.
When rubber cement is applied to the punctured spot, the solvent in it breaks down the upper layer of the inner tube and bonds it to the polymers in the fluid.
Once the rubber cement is, the solvent is gone, and the inner side of the applied cement is chemically bonded to the outer side of the tube.
The exposed side of the glue is ready to bond because it has free sulfur groups “in anticipation” to connect to others.
A classic inner tube patch has two sides. One is black, the other is orange and covered by foil. The orange side has a bunch of free sulfur groups also waiting to attach to others.

The orange side of the inner tube patch is ready for connection.
When you remove the foil and press the patch against the dried rubber cement, both sides chemically bond and merge on a cellular level. This process is known as rubber vulcanization.
The end result of those disulfide bonds is a single unit.
This explains why cured tire patches are so difficult to remove. The new patch is practically part of the inner tube.
No instant glue can match the bond while offering the same flexibility. For that reason, standard tire patches based on rubber cement are preferred over improvisation.
Temperature Changes Affect CA Glue
Low and high temperatures harm CA glue’s bonding strength.
One of the common ways to break a super-glued object without damaging it is to put it in the freezer for a while. At low temperatures, the glue becomes very brittle and so does the bond.
Small Flats Are Not An Exception
Pinhole flats seem like a good opportunity to use glue as a filler, but that’s not proper practice either.
You can certainly fill a small puncture, and the patch may even hold for a while, but the method has a downside that makes it a poor long-term plan:
As the tube is inflated, the puncture will become larger too. Since CA glue is not flexible, it will not expand along with the tube. Consequently, the adhesion could easily fail with use.
Repairing Small Tire Cuts
CA glue can help with cuts in the outer tire caused by small stones and pieces of glass.
One of the cheapest and fastest ways to mitigate the damage is to get out the small bits of stone and glass with a pointy object and then fill the cracks with glue.
Even in this case, the glue’s inflexibility is a downside. Sooner or later, the cut will open, which is why some people use rubber glue (e.g., Shoe GOO).
However, if the cut is really deep, you may have to sew or replace the tire.
Back in the day, I got a “through and through” 1cm cut on my rear tire after jumping from a curb and landing on a piece of glass.
To prolong the life of the tire, I applied an inner tube patch on the inside and super glue on the outside. The solution worked for a while, but eventually, the super glue fell off, and I had to reapply it.
TL: DR;
If you get a flat tire, patch it the old-school way – it works very well. Don’t mess with “magic glues”.
Until next time,
Rookie
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