  We analyze the phase space of Bianchi I cosmologies filled by a spin fluid in
the framework of $f(R)$-gravity with torsion using a combination of the
dynamical systems approach and the 1+3 covariant formalism. In the simple case
of $f(R)=R^n$ our results allow a quantification of the role of torsion and the
spin of the cosmic fluid in the evolution of the cosmology. While torsion is
able to modify the cosmological dynamics with respect to the purely metric
case, the spin has little influence on the cosmology. We argue that this is due
to the different symmetries of the tensor characterizing the anisotropies and
the spin tensor. The cosmological model we analyzed presents isotropization for
a wide set of initial conditions and values of the parameters and allows for
two types of exotic bounce solutions.
