...most IGH shifters won't fit on a mustache bar. Sturmey Archer is coming out with a bar end shifter that will, but so far they're not available. Maybe in a few months, though.
1) Riders have been mounting classic Sturmey triggers on road bars for over 80 years.
2) I'm sitting here holding my Sturmey SL-S30 bar end shifter in my hand. I've had it for about a month.
tcs