Is it possible to set only the textwidth and the inner margin
for a twosided layout?
As far as I can see, backspace sets only the _left_ margin
of odd _and_ even pages.
\definepapersize[new][height=240mm,width=165mm]
\setuppapersize[new]
\definelayout[odd][
topspace=14pt, header=14pt, headerdistance=22pt, height=20.2cm,
backspace=1.9cm, width=12.4cm]
\definelayout[even][
topspace=14pt, header=14pt, headerdistance=22pt, height=20.2cm,
backspace=2.2cm, width=12.4cm]
\setuplayout
\starttext
\showframe
\dorecurse{10} {\input knuth \endgraf \input tufte \endgraf}
\showlayout[1,pt,cm]
\dorecurse{10} {\input knuth \endgraf \input tufte \endgraf}
\stoptext
Herbert