As a strategy for reproducing rare, biologically important events, we previously developed the Outlier FLOODing (OFLOOD) method [J. Comput. Chem. 36 (2015) 97-102]. This method utilizes conformational resampling from rarely occurring states, detected as outliers, to promote conformational transitions relevant to the rare events. However, to perform OFLOOD efficiently requires specifying a set of appropriate reaction coordinates (RCs) with non-trivial specifications. Therefore, in this paper, we propose a strategy to obtain a set of appropriate RCs using a method where the best set of RCs are automatically searched from the initially given RCs, via clustering the states of biomolecules. (C) 2015 Elsevier B.V. All rights reserved.