Just remember that the bobweight % reduction by itself really applies to freewheeling....when applying power the net gain is lower (overall) because you have to calculate total which is the sum of all the rotating masses the motor is "seeing" from the nose of the crank to the back tires. it's still a reduction but the net reduction (in terms of the % TOTAL amount of mass being rotated) is obviously less. In the end the motor can only rotate under load as fast as the load it is driving through will allow it to.