We generalise a theorem of Gersten on surjectivity of the restriction map in \(\ell ^{\infty }\) -cohomology of groups. This leads to applications on subgroups of hyperbolic groups, quasi-isometric distinction of finitely generated groups and \(\ell ^{\infty }\) -cohomology calculations for some well-known classes of groups. Along the way, we obtain hyperbolicity criteria for groups of type \(FP_2({{\mathbb {Q}}})\) and for those satisfying a rational homological linear isoperimetric inequality, answering a question of Arora and Martínez-Pedroza.
