  Recent experiments showed that the last, single channel conductance step in
monatomic gold contacts exhibits significant fluctuations as a function of
stretching. From simulations of a stretched gold nanowire linked to deformable
tips, we determine the distribution of the bond lengths between atoms forming
the nanocontact and analyze its influence on the electronic conductance within
a simplified single channel approach. We show that the inhomogeneous
distribution of bond lengths can explain the occurrence and the 5% magnitude of
conductance fluctuations below the quantum conductance unit $g_{o}= 2e^2/h$.
