Try riding your bike on sand...
Remember, the moon's surface is covered with some pretty thick dust. It isn't a smooth, hard-packed surface. Go back to those videos of astronauts walking on the lunar surface or driving the Rover and you'll see dust flying everywhere.
Could you make a tricycle that can roll easily on lunar dust? Perhaps. It might be better to consider developing the rover so that parts of it could be salvaged easily to create a motorized tricycle capable of carrying both astronauts. Each wheel on the Lunar Rover was powered by its own electric motor. Perhaps the Rover could be redesigned to be disassembled easily and reassempled into a new vehicle (sort of an expensive "transformer") from the components.