Soil bioengineering techniques for riverbank protection are nature based solutions that have to fulfil most of the ecological functions of a natural riverbank, and they have also to achieve a sustainable erosion control function. Nevertheless, there are very few existing sizing methods, ant this lack is the main stand in the way of developing bioengineering techniques. Empirical experiences on mechanical resistance were recorded on works having resisted to flood during decades at the Alpine scale. We classified 18 soil bioengineering techniques according stream slope, shear stress for D84 and age since completion. Five experimental works were built in their limits of utilization, with river gradients from 4 to 10 % and high bedload transport. The shear stress resistance values of riverbank bioengineering works in the literature were then recorded. We compared these last values with 51 new shear stress values calculated for the maximum flood encountered by different riverbank works, including the experimental works. These results enable to refine the mechanical resistance thresholds of bioengineering techniques for riverbank protection. The increasing of the sites to be sampled for empirical experiences might give more precise value and knowledge about mechanical resistance, and reasons for failures. Further researches including flume experiment would enlighten some of the hydraulic processes responsible of the failures.