My bike has an i motion 3 hub, but i would like to pull the kids with it and need some help (besides going to the gym). Before I consider upgrading to a 7,8,9 speed hub I was thinking about using a smaller chainring. Right now it has a 42 teeth chainring 700 size wheels. What smaller size chainring could I match up with the sram i moton 3 hub (20 teeth)?

Someone told me 2 to1 was the lowest i should go but i would like to go lower than that. Is this a problem?