[James Tonthat]

Let's just say that you're using a 12:1 gearbox. That means that 12 turns of the input, gives you 1 turn of the output.

(Here's the USCS version)
Power [lbf*ft/s] = Torque [lbf*ft] * Angular Velocity [Rad/second]

Therefore (Power in is equal to power out, I know there are inefficients but for the sake of simplicity)
Torque [lbf*ft] * Angular Velocity [Rad/second] = Torque [lbf*ft] * Angular Velocity [Rad/second]
Torque of CIM * 12 = Torque output from gearbox * 1

So the output torque is 12 times the input torque. If you do the sprocket thing, that's an additional 2:1 (two rotations of the input, one rotation of the output), in this case you'd multiply the two.

Your overall ratio is 24:1 at this point.

What the Banebots spec is saying is that the OUTPUT of the gearbox cannot be more than 85 lbf * ft. This is probably because the final stage (piece of the gearbox) cannot handle stress greater than that spec (85 lbf*ft.) The input from the CIM would, of course, be much less than (85 lbf*ft), so yes there is no risk mechanically.

I probably didn't need to post this but just educational if you'd like. I'm going to guess you're going to be coming up with some sort of lift calculation. This will help you (remember keep track of your units.)

Power = Work / Time
Work = Force * Distance