The motions of a homopolyrotaxane composed of polyoxyethylene have been studied at 373 K in the dense melt and in systems obtained by dilution with a structureless Theta solvent. The sizes of the rings vary from (CH2CH2O)(10) to (CH2CH2O)(20). The dynamic Monte Carlo simulation employs a coarsegrained representation of the system that is constrained so that an atomistically detailed description can be obtained from any replica. Single bead moves, corresponding to the motion of 2-3 backbone atoms in the atomistically detailed model, are employed in the study of the dynamics. The motion has the characteristics of a one-dimensional random walk when it is monitored by recording the index of the bead in the linear chain that is the instantaneous site of the threading of the cyclic component. When the same simulation is monitored in a laboratory coordinate system, the motions in the systems with the structureless diluent are dominated by subchains of the linear chain component of the homopolyrotaxane, with only a minor contribution from the motion of the ring. In the dense melts the motions of the linear chain and the ring can be more similar in size, but no circumstances were found under which the motion of the ring became dominant over the motion of the linear component.