Résumé : A quantitative semantics for infinite timed words in timed automata based on the frequency of a run is introduced in [BBBS11]. Unfortunately, most of the results are obtained only for one-clock timed automata because the techniques do not allow to deal with some phenomenon of convergence between clocks. On the other hand, the notion of forgetful cycle is introduced in [BA11], in the context of entropy of timed languages, and seems to detect exactly these con- vergences. In this paper, we investigate how the notion of forgetfulness can help to extend the computation of the set of frequencies to n-clock timed automata.