Presta valve letting all the air out when I screw it back in I'm getting frustrated with my bike's Presta valve.
I spent 20 minutes before the air would move into the tube, all undone by screwing the end of the valve back in which temporarily releases air. I reckon it was 1.5 seconds of air release getting the end of the valve screwed back in.
Any tips on how I can avoid losing air?
If you press down while screwing in, air will be released. The nut on the top of the Presta valve does not need any downward force to close.
If you are not pressing down while screwing in or find a lot of force is needed to turn the nut at the top of the tube, then your valve may be damaged. At that point, it is best to get a new inner tube/valve.