% For polyrhythmic pieces we have to remove some engravers
% from score context and assign them to staff context.
% This snippet makes no use of Repeat_acknowledge_engraver and Volta_engraver
% But to make it easier to adapt the snippet to different needs,
% these engravers are mentioned here, too. You will need them as soon as you use \repeat.

upperVoice = \relative c'' {
  \override Staff.BarLine.allow-span-bar = ##f
  \time 3/4
  e4 f g
  a g f % since Staff.BarLine.allow-span-bar is set to ##f, bar lines are not connected
  e f g
  % if we want the BarLines of the Staves to be connected, we have to turn it on again
  a g f\bar"|." \once \override Staff.BarLine.allow-span-bar = ##t
}

lowerVoice = \relative c'' {
  \time 4/4
  c1
  c1
  c1\bar"|."
}

\score {
  \new StaffGroup <<
    \new Staff <<
      \new Voice { \upperVoice }
    >>
    \new Staff <<
      \new Voice { \lowerVoice }
    >>
  >>

  \layout {
    \context {
      \Score
      \remove "Timing_translator"
      %\remove "Repeat_acknowledge_engraver"
      %\remove "Volta_engraver"
    }

    \context{
      \Staff
      \consists "Timing_translator"
      %\consists "Repeat_acknowledge_engraver"
      %\consists "Volta_engraver"
    }
  }
}