Abstract: The finite length of strain gauges may induce filtering effects when measuring impact events. In this study, we are interested in quantifying these effects. Precisely, we determined the cut-off frequencies of strain gauges cemented on visco-elastic bars and measuring impact-induced strain waves. This study shows that the cut-off frequencies increase with the bar’s wave velocity and decrease with the bar’s diameter. The asymptotic value, corresponding to an infinite bar diameter, is reached rapidly (bar diameter ≈ 15 mm). Moreover, we showed that the mode cut-off frequencies are more severe (lower) than the gauge length cut-off frequencies for bar diameters greater than 8 mm.