  We report structural, magnetization, electrical resistivity and nuclear- and
electron spin resonance data of the complex transition metal oxide In_2VO_5 in
which structurally well-defined V-O chains are realized. An itinerant character
of the vanadium d-electrons and ferromagnetic correlations, revealed at high
temperatures, are contrasted with the insulating behavior and predominantly
antiferromagnetic exchange between the localized V^{4+} S = 1/2-magnetic
moments which develop below a certain characteristic temperature T* ~ 120 K.
Eventually the compound exhibits short-range magnetic order at $T_SRO ~ 20 K.
We attribute this crossover occurring around T* to the unusual anisotropic
thermal contraction of the lattice which changes significantly the overlap
integrals and the character of magnetic intra- and interchain interactions.
