If you want to look at the math of the kind of loads chains or belts take and design the system appropriately, you can take a look here:
https://www.chiefdelphi.com/media/papers/3292
I stepped through the math to help with understand the loading. It all depends on the drivetrain setup. #25 chain may work for one style of drive and not another. Belts may work, or you may need #35 chain, just take a look at the math.