Hm, probably didn't make it too clear (apart from saying I carry adaptor in pocket of jeans) but this thingie is NOT something
you would keep permanently attached to the bike. Mate tried that years ago & found out the hard way, it will destroy the
existing valve stem. This product is only for use when using the tyre pump.
If you can find a stock setup valve that is bent out or attached to the side of the rims, cool. But not too may sickles have that.
The adaptor is the next best option I have found, but NO, don't leave it attached.
As V-Twin stated, centrifical force is not to be toyed with!
Here's an insight into centrifugal force on the bike wheel. A local mate of mine and his son race on the Isle of Mann where things can get very fast. The son was having trouble keeping his tyres inflated and was having to check them every few laps. They worked out that the centrifugal force was pushing the valve down very slightly and the plastic caps allowed air to escape. So they changed to metal valve caps with washers inside to give a tighter seal. That solved the problem. For tubeless tyres you can get 90 degree valve stems that mount securely to the rim. Leaving a temp bent stem on while you ride is a no no.
From Woodrising (no, nobody else has heard of it either) Rides a Springfield Dark Horse