I am working on a mobile robotics project and I'm beginning to learn about DC motors. I am looking at a particular geared motor, and the given parameters are the no load speed, the rated torque, rated voltage and rated current. I am confused on how to find the rated speed (the speed the motor will run if given the rated load) using these parameters. The data sheet for the motor is not provided, but the motor itself can be found at this link: https://www.amazon.com/Greartisan-Electric-Reduction-Centric-Diameter/dp/B071GTTSV3?th=1.
I know that torque and speed are inversely proportional at a given voltage, and I have tried to calculate it using that relationship, but I think that my method is flawed. I was looking at another motor's data sheet, and I was not getting the result that was stated on that data sheet.