Pump some air into the tube. Listen for a hiss or feel for airflow. If you’re at home, submerge the tube in water; a stream of bubbles will pinpoint even the tiniest "slow leak."
Before you start, you need to know which tool you’re using. Bicycle Inner Tube Patches
These kits come with a small tube of "rubber cement." This isn't actually glue; it’s a chemical agent that melts the patch and the tube together into a single, seamless piece of rubber. Once cured, the patch is often stronger than the rest of the tube. How to Patch a Tube in 5 Steps Pump some air into the tube
Peel the foil backing off the patch (try not to touch the sticky side) and press it firmly over the hole. Use your thumb to apply heavy pressure from the center outward to work out any air bubbles. These kits come with a small tube of "rubber cement