nanotubes from chiral bisurea monomers. Furthermore, similar helical nanotubes (with the same circular dichroism signature) can be obtained from racemic monomers in a chiralsolvent. Competition experiments reveal the relative strength of the helical bias induced by the chiral monomer or by the chiralsolvent. The nanotube handedness is imposed by the monomer chirality, whatever the solventchirality. However