Head impact sensors measure head kinematics in sports, and sensor accuracy is crucial for investigating the potential link between repetitive head loading and clinical outcomes. Many validation studies mount sensors to human head surrogates and compare kinematic measures during loading from a linear impactor. These studies are often unable to distinguish intrinsic instrumentation limitations from variability caused by sensor coupling. The aim of the current study was to evaluate intrinsic sensor error in angular velocity in the absence of coupling error for a common head impact sensor. Two Triax SIM-G sensors were rigidly attached to a preclinical rotational injury device and subjected to rotational events to assess sensor reproducibility and accuracy. Peak angular velocities between the SIM-G sensors paired for each test were correlated (R2>0.99, y=1.00x, p<0.001). SIM-G peak angular velocity correlated with the reference (R2=0.96, y=0.82x, p<0.001); however, SIM-G underestimated the magnitude by 15.0% ± 1.7% (p<0.001). SIM-G angular velocity rise time (5% to 100% of peak) correlated with the reference (R2=0.97, y=1.06x, p<0.001) but exhibited a slower fall time (100% to 5% of peak) by 9.0 ± 3.7 ms (p<0.001). Assessing sensor performance when rigidly coupled is a crucial first step to interpret on-field SIM-G rotational kinematic data. Further testing in increasing biofidelic conditions is needed to fully characterize error from other sources, such as coupling.