How to fix a leaky tire with a presta valve? You may have a leaky tire because the valve core on the inner tube valve stem shipped loose from the factory.
To fix a leaky tire in this case all you need to do is make sure the valve core body is tightened on the valve stem. Use some small pliers, a wrench, or a valve core remover tool specifically for this purpose.
You may also have unintentionally loosened the valve when using a screw on pump head. I would suggest getting a pump with an air hose that has a push on head and clamp, and try to remove the pump head in a straight direction when done to avoid bending the valve stem.
Why would you buy a tire tube with a removable valve core? A removable valve core can be useful for replacement in case of failure (leaky valve), for adding extenders needed for deeper wheel rims, or for using tire sealant (slime) on an existing tube.
The tire inner tube presta valve featured in this video is a Continental Race 28 bike tube.
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