  We report on an ongoing study of the running coupling of SU(N) pure
Yang-Mills theory in the twisted gradient flow scheme (TGF). The study exploits
the idea that twisted boundary conditions reduce finite volume effects, leading
to an effective size in the twisted plane that combines the number of colours
and the torus period. We test this hypothesis by computing the TGF running
coupling and the SU(N) $\Lambda-$ parameter on asymmetric lattices of size
$(NL)^2L^2$ for various gauge groups. Finite volume effects are monitored by
analyzing the coupling in different planes and by comparing results at
different number of colours.
