In this paper, we propose a new protocol named DRBT (Dynamic Regulation of Best Effort Traffic) which supports QoS throughput guarantees and provides a distributed regulation mechanism for Best Effort traffic in multihop wireless networks. By adapting dynamically the rate of Best Effort traffic at the link layer, DRBT increases the acceptance ratio of QoS flows and provides a good use of the remaining resources through the network. Our protocol also provides an accurate method to evaluate the available bandwidth in IEEE 802.11-based ad hoc networks which is able to differentiate QoS applications from Best Effort traffic. Through extensive simulations, we compare the performance of our proposal scheme with some others protocols like QPART for instance.