I created with Solidworks a reducer composed of a classic gear followed by an epicyclic train. I wanted to know how to make a simulation on Solidworks or any other software to check the mechanical stresses, the friction according to the rigosity of the parts, the forces applied on the sprocket teeth, the resistance of the parts according to the rotation speed of my motor and the material used ect ... I'm going to 3D print it and I didn't want to do it without simulating it on a computer.
So you're going to start by doing manual calculations of torques and efforts. And from there you will calculate your parts (or small pieces of assembly).
You can also get out of solidworks motion efforts and reuse them in cosmosworks (never used but it works a priori). But this is surely more useful on kinematics (like backhoe loader arms) than on sprockets (SW will not manage the rotation).
If you have a big PC and you have time to spare: you model your entire assembly in cosmosworks: you manage the contacts between your different parts, you put your torque on the input shaft and you block your output shaft. There is a 99% chance that cosmosworks will not be able to do the math (since you have several gears, there is a good chance that the mechanical stresses will make your sprockets rotate and that the contacts will change teeth...) and 1% chance that you will get the stresses in your entire assembly at once.
If you've never used cosmosworks (solidworks simulation), it's unlikely that you'll be able to get anything out.