Where on the presta valve does it screw onto?
Does this screw onto the threads the cap attaches to or the thrads on the stem of the valve?
Just checked. It screws onto the smaller thread on the valve core, not the wider fixed thread. So, as with most pumps, there's still the potential to unscrew the valve core. In my experience, you really don't need to screw it on at all tightly. Also, as there's a pressure release device, the connector does not bind onto the valve.
Hope this helps
10 months ago