Originally Posted by Leukybear

Going up hills fixed is easier because you are able to use your weight (yes, as with any bike) to push a foot/ pedal down whilst bringing up the opposite BUT thanks to the inability to coast/ being directly interconnected to the drivetrain, your other/ opposite foot has to go up no matter what, setting you up perfectly to use your weight again without having to pull up with the other. With a freewheel you don't get this type of interconnectivity/ momentum from the wheels.