  We show that gapless spin liquids, which are potential candidates to describe
the ground state of frustrated Heisenberg models in two dimensions, become
trivial insulators on cylindrical geometries with an even number of legs. In
particular, we report calculations for Gutzwiller-projected fermionic states on
strips of square and kagome lattices. By choosing different boundary conditions
for the fermionic degrees of freedom, both gapless and gapped states may be
realized, the latter ones having a lower variational energy. The direct
evaluation of static and dynamical correlation functions, as well as overlaps
between different states, allows us to demonstrate the sharp difference between
the ground-state properties obtained within cylinders or directly in the
two-dimensional lattice. Our results shed light on the difficulty to detect
bona fide gapless spin liquids in such cylindrical geometries.
