Torque is just perpendicular force x distance from the axis
There was talk about measuring against something "resistive". I can only assume you mean the opposing forces on a bike, namely acceleration and aerodynamic drag, which accounts for 90% of a cyclists power output at a constant speed.
Yes, hence my comment that the best way to start is with the bike stopped. But I thought the whole exercise was impossible without even getting round to addressing the biggest obstacle. Apparently I was wrong about that.