Our quick-and-easy, no-fail way to swap a punctured tube
If you do even a moderate amount of riding, you are going to get a flat tire at some point. The good news? You can become a skilled flat-repair expert in no time.
What you'll need:
• a new tube
• 2 tire levers
• a floor pump, hand pump, or CO2 cartridge and inflator
Remove the Innertube
Open the quick-release or unbolt the axle and remove the wheel from the bike. Remove as much air as possible from the tire by compressing the valve stem.
Working at the area opposite the valve stem, use the rounded end of a tire lever to pop one bead (the hard edge of the tire) off the rim and hook the other end of the lever onto the spoke below. This will keep the bead from jumping back into the rim. Now work the second lever under the bead to the right of the first until there's enough slack to move it freely.
Slide the second lever around the rim clockwise until one bead is entirely off. Pull the tube out of the tire.
Find the Puncture
To avoid getting another flat quickly, find the cause of this one. Inflate the tube to locate the leak.
Run your gloved hand or a piece of cloth along the inside of the tire to feel for any debris penetrating the tread. Now check the outside of the tire for objects that haven't worked through the tread yet. Remove all debris.
Install the New Tube
Do not try to use a Philip or Flat screw driver in installing your new tube. This will just puncture your new tube
Align the label on your tire with the rim's valve hole (this will make future punctures easier to locate). Inflate your new tube just enough to hold its shape, insert the valve into the rim, and tuck the tube into the tire.
Beginning at the valve stem, work around the circumference of the tire, using the heels of your hands to push the bead back onto the rim. Make sure the tube isn't getting pinched between the rim and tire as you continue on.
When you reach the area opposite the valve stem, you may need to put a little muscle into getting that last part over the edge of the rim. Tip: Push the valve stem up into the tire so the bead can pop more easily over the rim wall.
Reinflate the tube to around 20 psi, then check that the tire is properly seated on both sides of the rim. If it is, fully inflate it to the psi recommended on the tire's sidewall or to your desired pressure.