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@gbj_tester
Jeeez, what are they teaching in school these days?
Power = Force x Velocity
For rotating machines,
Power = Torque x Angular Velocity
So, given that all other things being equal the force resisting the forward motion of the bicycle is constant at constant velocity, the power needed to maintain this velocity is also constant. Even if you change the ratio between the pedal speed and the bicycle speed, you will need to keep the product of pedal force and pedal speed constant. Here are the things you can do:
Increase chain ring (or wheel) size => lower pedal speed => higher pedal force
Increase sprocket size => higher pedal speed => lower pedal force
Increase crank length => higher pedal speed => lower pedal force
Power remains constant in all cases. In the third case, angular velocity of the crank (i.e. cadence) and torque also remain constant, since you haven't changed the gearing.