Here is a new idea for an electric unicycle; at least it is new to me.
The pedals on a unicycle perform two functions; they deliver power and act as control surfaces. The pedals control the speed of the unicycle and allow the rider to maintain balance. One could separate these functions to develop an electric unicycle that would be controlled by the pedals to give the feel of a real unicycle.
- Pure electric unicycle.
The idea is to use an electric motor to drive the wheel. One should be able to adapt electric bike technology to accomplish it, and it would be ideal if the motor were high torque and reversible. The pedals themselves would just have a friction drag at the axel to give some resistance, and would be tied to an encoder, which precisely measures the RPM of the axel and converts it to a digital signal. To speed up you would pedal faster, and to slow down you would pedal slower. The output from the encoder would be used to control the motor, and if we had a very good digital controller one would get precise and nearly instantaneous control of the wheel motion—almost as if they were connected. This idea would basically take a “self-balancing unicycle” and return the control to the rider.
The advantage of this method is that it decouples the speed of the pedals from the speed of the wheel (and it makes riding much less work.) With a digital controller, you could start at a 1:1 ratio and take it up smoothly to any practical ratio such as 1.5:1 or 2:1. This system would give you electronic control of the gearing without using any physical gears.
- An electronic unicycle you could ride
If the control system works, one could return to the design table to make one that is actually fun to ride. The only real change is to connect the axel to a generator and use it to feed the electric system. Presumably you would still need a battery to get started, and also to act as a power reservoir.
The advantage of the system is that you would now have a Schlumpf equivalent, but with continuous gearing from below 1 to whatever value the power output would support: perhaps from 0.7:1 to 2:1. It could be shifted on the fly with a dial, and adjusted to uphill and downhill riding. Since the system is electric, you could charge up the battery on easy parts of the ride and use the added energy on the hills. You also might be able to include electric braking to charge up the battery, as Justin Le did with his “electric assist” unicycle.
The disadvantage is the generator efficiency. You will loose some energy converting to electric and back. If the efficiency were too low, the whole thing would be impractical.
I can envision the idea, but its implementation is beyond my skills (or available time). If it worked, it would make a very cool road unicycle, perhaps in a convenient 26” or 29” size.