Originally Posted by rhm
Yeah, that makes sense, at least intuitively. And that may be why Strida freewheels fail once in a while. But on the other hand... the hub is designed as one element of a system that transmits the torque from your legs to the wheel. That's all we'd be doing, albeit at the other end of the chain. So why should there be any difference?
Because on a normal bike, every time you turn the (larger) chainring the (smaller) rear sprocket turns many times. More distance (actually rotations) is traded for less force (actually torque).
The gear system works at every point along its path. If you connected the wheel to the cranks (as with a unicycle or penny farthering) then you'd have a very low gear. Low gears provide more torque (for hauling that load of groceries up hill, for example). Therefore, relocating a component to the crank end of the chain will result in more torque.
Even the Rohloff requires no less than 2:1 gear ratio from the cranks to the hub. Maybe the Sturmey-Archer 8-speed could take the punishment since it takes an unusually large rear sprocket.