[Tristan Lall]

With those ratios, you're going to spend most of your time in high gear (if your driver knows what's good for them...), and use low for getting out of defence or pushing objects. And with that top speed, you won't stall, but you will pull significant current as you depart from a standing stop.

If you can shift fast, you can mitigate this by starting in low, and then transitioning to high quickly—it might be worthwhile to automate this.

Another solution is to add motors—because that spreads the load across more circuit breakers and more motors, for better overall performance. But that would require re-engineering the Super Shifter a little bit. (I've done it before; it's not a huge deal, especially if you're starting now.)

As for the chain, if you engineer it correctly—as Joe described—you can make it work. Understand the relationship between tension in the chain and torque on the shaft, and you'll get a good idea if you're exceeding the manufacturer's specifications. (Remember to consider the case of sudden reversing loads.)