What Components of an Electric Unicycle are the Heaviest?
Posted by Tom Lee on
One fairly common misconception about Electric Unicycles is that they weigh what they do because of the weight of the battery pack. In a top-of-the-line Electric Wheel, like a King Song with a 840Wh battery, it’s true that the batteries are not exactly light; however at most, they represent at around 20% of the Wheel’s weight.
With most Wheels, the motor constitutes around 50% (or more) of the total weight. This is because the components that make an electric motor work are intrinsically heavy: there are the permanent magnets on the rotor (the part that spins), a lot of heavy copper, steal cores that copper winds around & usually a steel or aluminum support structure.
Where the Wheel is not being ridden, even for healthy/strong individuals, having to carry the Wheel even for short distances can be a real effort. To solve this problem, the top manufacturers have designed handles either retract into the body of the Wheel (King Song 16), or fold elegantly away as a bolt-on accessory.
As Wheels continue to evolve, we can continue to see improvements in areas like product weight, but dramatic overnight weight reductions are unlikely…
According to these scales, the total Wheel weight with everything still attached is just a tad less than 17kg.
Inner shell with the retractable handle is 2.6kg
A view from the top of the Wheel: notice the opening with proper seal to prevent water from getting underneath the board.
Control-board is only 250gm including the heat-sink.
Each pedal with rubberized surface is 650gm.
Pair of aluminum pedal support arms weigh 750gm.
Each 18650 cells is pretty standarized at 45-50gm each. The MJ1 has a specification of 47gm, with 64x of these, the batteries themselves weigh 3kg, with another 250 gm for packaging, wires, conductive connecting strips.
Finally the motor with the pedals & support arms attached—in the graph, I excluded these parts from the motor weight. The tire & inner-tube weigh around 1kg by themselves, so the motor weight itself is around 6.5kg
