The 4-speed trigger has worked for me on my ASC for a couple of decades. Only two cautions: (1) stopping in the "3" position may give you freewheeling, but occasional sounds of chipping teeth, and (2) it wants pretty high tension on the wire to reliably stay in "1". This, of course, may reflect some wear on my trigger.
I've only seen 1 true ASC trigger, Mr. Artley's.
harvey sachs mcLean va
Hugh, I think Sheldon Brown had demonstrated that an S-A 4 speed shifter will work using 1st,2nd and 4th positions....if memory serves. I have 2 ASC's and have yet to build them up. I also think a bar end shifter will do as well...all if the fabled ASC shifter evades discovery. I don't have the ASC shifter for either of mine but have set aside 2 S-A 4 speed shifters as well as a Cyclo ball-end bar-end when the time comes.
Matt Gorski Belmont Shore, CA
################################################################# ################################################################# ################################################################# ##### ##### ##### ################################################################# ################################################################# #################################################################