What is the best glue to fix tire air leak on bicycle ?

If you’re talking about mountain biking abs getting punctures, try downhill racing tubes. They are much thicker. When I used to go mountain biking regularly , I was experiencing a puncture every 2-3 weeks with conventional tubes. Swapping to downhill tubes , it became about 1 a year.

They are harder to fit and generally available in wider sizes, so no good for road bikes, but otherwise, highly recommended.

I would be bankrupt if I need to buy a new tube every time I get a flat. That is because practically every time I go out riding and leave my bike to go buy something, I get a flat. when I come out of the store. I get 2 punctures side by side on the same tube about an inch apart when I repair them. I wonder what kind of tool was used to put those holes in my tire tube.

For repair I get Rema patches and use the rubber cement that come with the patch kits.  Recently I bought some tube repair patches off Amazon when I was running low on Rema patches.. They are rectangular and much stiffer than Rema patches. Also much cheaper.  To my pleasant surprise, they work just as well. I also bought a can of Slime rubber cement because the little tubes were running out. So far they have worked. 

Successful repair depend on the correct procedure being followed.  The correct procedure is to find the leak first, then sandpaper it. Then put rubber cement on the tube and wait at least an hour or wait overnight for the cement to completely dry. Then you put a patch on the dried cement and use a vise grip to clamp the two together for a couple of minutes. I inflate my tires to about 80 psi using an electric pump, and they appear to be holding up. 

"User" stated, "You can get better results by purchasing puncture-proof tires..."  There's NO SUCH THING as a puncture-proof tire!  Puncture resistant?  Yes.  Puncture-proof?  Sorry...no.  I do agree with his choice though.  There's no tougher puncture resistant tire than the Gatorskin from Continental. https://www.continental-tires.com/bicycle/tires/ra...  Your choice of wire bead or foldable bead in most sizes.

You can patch tubes several times before I'd call them useless.  Patch kits are inexpensive.  Learning how to do it right may be another story.  I'll post a YouTube video from Park Tool at the bottom.

Now let's talk about WHY you're getting so many flats.  I honestly can't remember the last flat I got.  And I live in a city filled with potholes, broken glass & all sorts of debris.  In all capital letters...I DON'T HUG THE CURB OR GUTTER!  I always ride a good 5 feet or more away from the curb.  That's where all the debris ends up.  In a narrow lane situation (at or under 14 feet wide) I TAKE THE LANE!  Here's the math...  A bike lane by Federal Standards must be at least 5 feet wide.  And even a small car mirror-to-mirror is 6 feet wide.  Safe passing in most states is a minimum 3 feet.  5 + 6 + 3 = 14 feet.  So...a lane only 12 feet wide is too narrow to "share" with another vehicle.  Read Bicycling Street Smarts on this link... http://www.bikexprt.com/streetsmarts/usa/index.htm  Quote from chapter 2, "With very few exceptions, the safest way to ride is as part of the traffic, going with the flow of the normal traffic pattern."  

Invest in some better puncture resistant tires and DON'T hug the curb.  Here's the video...  https://youtu.be/T0F_hibWHlU 

I'm sure there are many videos on Youtube showing you exactly how to fix a flat bike tire. Learn how to do it and carry a patch kit and pump when you ride. It's easy and it's a skill every bike rider should know. Replacing the tube doesn't save you very much work anyway.

#1

They make tube repair kits. ALWAYS have such a kit and a tire pump with you when you cycle.

I would recommend the "Park Tool" or "Slime" brands. Both have a top-notch reputation.

https://www.amazon.com/Park-Tool-VP-1-Vulcanizing-...

https://www.amazon.com/Slime-1022-Rubber-Tube-Patc...

#2

Get better tires and new tubes.

You can get better results by purchasing puncture-proof tires for your bicycle. The good ones aren't cheap! But in the long run they'll save you lots of money on tubes.

Here is one of the top-rated examples:

https://www.amazon.com/Continental-GatorSkin-DuraS...

You can also consider using tube protectors (example)

https://www.amazon.com/Armour-Tannus-29-1-95-2-5/d...

but they are nearly as expensive with, typically, not quite as good results.

A final option is the "self-repairing" tube

https://www.amazon.com/Slime-Schrader-Bicycle-Seal...

If you use your bicycle for very important travel - such as to and from work - then consider ***using puncture-proof tires AND tube protectors***. You can also add in the thorn-proof tubes for yet another layer of protection. Consider the expense an investment in the reliability of your transportation.