Opportunistic routing (OR) has been introduced to enhance network performance of Wireless Mesh Networks (WMNs), utilizing the broadcast nature of the wireless medium. Rate Control (RC) has the potential to further improve the efficiency of OR as it has an impact on how many nodes in the network are able to receive a packet from the sender. However, the implementation of an efficient RC mechanism in OR is still an open research topic. We propose a novel Rate Probing mechanism applying cyclic feedback, to effectively bypass limitations from missing direct ACKs in OR. Additionally, we present agglomerative hierarchical clustering to reduce the probing pool of transmission rates, mitigating probing overhead caused by a growing number of available rates. With our proposed methods, we were able to reliably adapt to rapid link quality distortions.