We performed X-ray diffraction, magnetic susceptibility, and magnetization experiments on nonequilateral triangular spin tubes composed of α-KCr Fe F (x = 0∼0.13), which consisted of one-dimensional Heisenberg antiferromagnets coexisting with geometrically-frustrated spin systems with bond randomness. The variation of lattice parameters with x may indicate that the Fe ions constitute the low-spin state (S = 1/2). As a result of analyses of the frustration factor and the spin-flop transition field, we found that the effect of geometrical spin frustration was enhanced and that the magnetic anisotropy was weakened as x was increased. Because these results are remarkably similar to the previous results for α-KCr Al F , the effect of the chemical impurity substitutions, whether they are magnetic or nonmagnetic ions, on α-KCrF is clearly understood. © 2013 The Korean Physical Society. 1-x x 4 1-x x 4 4 3+