The smart thing is to support the valve stem with a finger behind the stem.
I would argue the smarter thing is to replace the valve stems with 90 degree all metal stems.
Stock are 90 degrees and all metal stems.
Have you never looked at them??
The smartest thing would be to never have to replace them!
***
I have inspected them in a most intimate and personal way.
The stem itself is metal, as is the base inside the rim. However, unlike the PatchBoy stems which are a solid piece through the rim, the OEM valve stems are two piece and separated by the rubber seal at the rim.
Note the two separate pieces in my hand in the picture (The interior part and the outside stem). This seal at the rim is where the crack was, and the cause of the sudden dramatic loss of air pressure at speed.
Trust me, you do not want to wait for the stem to fail. If it is cracked, it is simply a matter of time until failure occurs (hopefully while parked, but more likely at speed) If it happens at speed and you are lucky like I was you will simply be looking at a tow bill and some creative engineering to get back on the road (hope you carry a C-Clamp in your saddle bag) If you aren't lucky I wish you luck and soft landings.
