Increasing demands on computing power have spurred the development of faster, higher-density Integrated Circuits (ICs), compounding power and complexity concerns in design budgets. The clock distribution network is a significant contributor to such power and complexity concerns. Resonant rotary clocking is a relatively new technology that realizes several benefits over current clocking methods, including power, frequency, and variation tolerance, yet lacks the automation tools to promote increased use. Towards this end, an automated rotary clock routing methodology is presented that generates custom topology rotary ring routes with tree subnetworks. In addition to the benefits of adiabatic clocking, the presented custom topology router permits 38.6% shorter wirelengths on average for register tapping, compared to traditional prescribed skew, binary tree routing. ACM Reference Format:Taskin, B., DeMaio, J., Farell, O., Hazeltine, M., and Ketner, R. 2009. Custom topology rotary clock router with tree subnetworks.