This study was designed to investigated resistance (force) settings for 30s tests of maximal anaerobic power output on a modified Monark bicycle ergometer. Twelve active to highly trained adult males had multitrial determinations at various resistance settings to obtain the true force to elicit maximal power output in 30s (FMPO). True maximal power output (MPO30s), mean = 661.6W was reliable on a test-retest basis (r = 0.96), and significantly (p less than .05) exceeded the power output obtained with the weight-relative Wingate protocol, mean = 588.4W. An optimal combination of resistance setting and pedalling speed seems necessary to elicit true maximal power output for an individual in a 30s ergometer test. Regression equations were developed from (a) anthropometric measures, weight and leg volume, and (b) from a pretest power output at 5.0 Kp, both to predict FMPO and obviate multitrial tests: (a) FMPO, Kp = -0.4914 - 0.2151 (WT, Kg) + 2.1124 (LEGV, L) with standard error of estimate of 0.83 Kp and multiple R = 0.87, (b) FMPO, Kp = -9.0166 + 0.0291 (PO5Kp, W) with standard error of estimate of 1.02 Kp and R = 0.77.