OK so to back up my comments on this being completely wrong, lets do the math by hand and show our work. If we figure wheel torque on a mid drive (or any pair of gears) by hand, the formula is

*Motor Torque * Gear Ratio = Wheel Torque*
Lets pick 80 Nm and ignore the fact that the geared hub is only capable of this momentarily (Bafang G060) and the mid drive can sustain this for longer periods (Bafang BBS02 in its 250w version) until it basically blows up. The purpose here is to demonstrate wheel torque is always multiplied by gears, not analyze the motor's efficacy (

that can be done on the Grin Motor Simulator quite nicely, BTW, but its not easy to set up).

My front chainring is a 36T, which is an actual aftermarket ring available from Lekkie, and right in the ballpark for a typical emtb chainring size. You'll see why I picked it in a minute. For the singlespeed hub, gear ratio is 1:1 since the sprockets are irrelevant and power is delivered thru the axle. So

**80Nm x 1 = 80Nm**
No surprise there. And remember we're not commenting on whether that will work for the use case. We're figuring out if torque multiplication is a myth. Now for the mid drive: We have a 36T in front, lets use a Shimano HG-400-9 that I use on both my hub commuter bike and its mid-drive hill-climbing successor: whose cogs are 12-14-16-18-21-24-28-32-36.

So our gear ratios are:

**12T: 3.00 (36T / 12T)**

14T: 2.57 (36T / 14T)

16T: 2.25 (etc. etc.)

18T: 2.00

21T: 1.71

24T: 1.50

28T: 1.29

32T: 1.13

36T: 1.00
Using the formula for wheel torque, the torque numbers for each gear are

**12T: 80Nm * 3.00 = 240Nm**

14T: 80Nm * 2.57 = 206Nm

16T: 80Nm * 2.25 = 180Nm

18T: 80Nm * 2.00 = 160Nm

21T: 80Nm * 1.71 = 137Nm

24T: 80Nm * 1.50 = 120Nm

28T: 80Nm * 1.29 = 103Nm

32T: 80Nm * 1.13 = 90Nm

36T: 80Nm * 1.00 = 80Nm
So... torque multiplication exists on every gear, and the multiplication is not only for sprockets the 'size of dinner plates'. In fact torque multiplication works in the opposite direction: The big cogs have

**less **multiplication, which is what makes them easier to muscle thru when pedaling. Which makes them easier for the motor to turn fast, which makes you go up the hill more efficiently without making the mid drive work harder than its able, bog down and create heat vs. creating motion.

And you can see why I picked a 36T front ring - thats a 1:1 gear ratio. So now lets say you shift from your 36T cog to your 24T cog. You've multiplied your rated torque (whatever the motor's true number is) by 50%. If the motor is strong enough to spin that cog, you've got your mechanical advantage. Thats why mid drives are used on bikes that live for hills.