  Lattice simulations of Yang-Mills theories coupled with $N_f$ flavours of
fermions in the adjoint representation provide a way to probe the
non-perturbative regime of a plethora of different physical scenarios, such as
Supersymmetric Yang-Mills theory to BSM models. We are interested in the
large-$N_c$ limit of these theories, for which standard lattice techniques are
limited by high-computational costs. Our approach makes use of the
well-established twisted volume reduction, which allows one to simulate these
theories on a $1^4$ lattice. In this talk, we are going to present a detailed
study of the scale setting of these theories, performed with Wilson flow
techniques, but endowed with a procedure that allowed us to reduce
finite-volume (finite $N_c$) systematic effects. We will apply this procedure
to our configurations for $N_f=0,\frac{1}{2},1,2$ and analyze the dependence of
the scale on the coupling, the adjoint fermion mass and the number of flavours.
For the cases in which enough couplings are available we compared the resulting
$\beta$-function with the predictions of perturbation theory, finding very good
agreement.
