3000W Unicycle’s Only Limitation Is “Personal Courage”

Electric vehicles are fertile ground for innovation because the availability of suitable motors, controllers, and power sources makes experimentation accessible even to hobbyists. Even so, [John Dingley] has been working on such vehicles since about 2009, and his latest self-balancing electric unicycle really raises the bar by multiple notches. It sports a monstrous 3000 Watt brushless hub motor intended for an electric motorcycle, and [John] was able to add numerous touches such as voice feedback and 1950’s styling using surplus aircraft and motorcycle parts. To steer, the frame changes shape slightly with help of the handlebars to allow the driver’s center of gravity to shift towards one or the other outer rims of the wheel. In a test drive at a deserted beach, [John] tells us that the bike never went above 20% power; the device’s limitations are entirely by personal courage. Watch the video of the test, embedded below.

We covered [John]’s previous unicycle which used a brushed DC motor and chain drive; the main factor limiting the use of brushless hub motors was the availability of a suitable speed controller. For use in a self-balancing vehicle, the speed controller must provide solid control in both forward and reverse directions, but most are set up to drive forward only. [John] found a solution in the form of a speed controller designed for an electric boat, but still needed to do some integration work to turn PWM into a smooth analog voltage by hand-soldering an LTC2644 DAC. Power comes from twenty LiFePO4 cells in the cylindrical fuselage above the wheel, and switches and knobs provide fine-tuning of the control software. Since the build lacks any sort of digital display, an Arduino using the Talkie library from [Peter Knight] provides an 80s-style computer voice to speak alarms and status to the driver. Even though assemblies like the motor and speed controller were key parts of making the build possible, there was still a lot of work needed for integration and in software.

[John] really knows his stuff; he has a resource page on self-balancing vehicles in general, and here’s a link to a YouTube playlist of the build process of this latest unicycle in particular. Great work!

37 thoughts on “3000W Unicycle’s Only Limitation Is “Personal Courage”

      1. I think the idea is that having the vehicle leap out from under you is more manageable and less of a risk overall than tipping forward out of control. (After all, on a self-balancing vehicle if you’re in motion then you’re always leaning forward somewhat.)

        1. I have faceplanted on an earlier machine which hurt a lot even with an armoured jacket and motorbike helmet. It is recorded here for your delight:

          This prompted the design of a safety skid as tipping forward and rolling to a halt is generally much better. In general though, the aim when things are going wrong is to lean back with feet apart dragging on the ground to give an extra braking effect. If you hand on to the handlebars the machine then exits forwards from underneath you and tips back. After a few times you can even make it look as if that is what you intended to do all along!

          1. If the handlebar pivot was in the back, and the unit suddenly stopped, couldn’t you just put your feet down first instead of face plant?

    1. While 4hp doesn’t sound like much, it’s nothing to scoff at. As a non-sequitur example, a 1hp drill press will readily remove fingers from your hand.

      Back in the day (get off my lawn you little bastards) we built go-karts with 3-5hp tiller engines that would get us into plenty of shit your pants moments.

      It’s a super cool build and I wish I had one.

      1. Thinking of people in some countries who walk carrying heavy loads on their heads, all the weight is carried vertically through essentially one point of contact with the ground. So, on level ground, you have rolling resistance of a single wheel, one pair of axle bearings, plus wind resistance. In addition your motor controller has regenerative braking so by slowing down you are not just generating heat in a brake rotor. In theory therefore it should be an extremely energy efficient means of transport. Self-balancers need plenty of power in reserve to regain balance in the event of a wobble, on level ground they draw very little current. It would be an interesting experiment to compare the ranges of a monowheel and an e-bike with the same motor and battery packs running side by side the whole way.

        1. On a normal two wheeled bike you do not need to waste much power to control balance. Even with regenerative braking this will provide some loss. Compare it with reactive power in an AC system. It does not provide real power, but it produces losses in components like generators, transformers and wires.

    1. I believe the Ryno “moved to a licensing model” in 2013 after about 20 machines had been built.

      It did 10mph and cost just over $5000. The basic steering geometry was preceded by that of the Enicycle by Alezxander Polutnik, see enicycle.com

      It had two Chinese brushed DC motors acting on a common toothed drive belt system within the rim. I genuinely hope the licensing process was successful and the inventor is making some money as an almost exact visual copy is available from China, hopefully as part of his license and not just a blatant rip off. I remember tipping Ryno off about it at the time. It looks similar from a distance but mechanically you can see costs have been severely cut.

      For example if you look at this advert on Alibaba, it has pictures of an inferior product but if you then scroll down the page you will see a picture of the real Ryno taken from the marketing material of the US Ryno website.

      https://www.alibaba.com/product-detail/New-Products-2017-Roller-Board-Electric_60743833792.html?spm=a2700.details.maylikever.7.32c52b3eei97e7

  1. Does she ride on the bars? And, is there an optional seat for that? And as long as it’s being asked, does she face forward, or rearward? Now jokes aside, you are facing a serious challenge with a one-wheeled wonder… I hate HATE ALL but the smallest twisting roller coasters, but since Honda is flirting with many 1 wheeled elec people-movers, I’d try yours. May I suggest knee pads, affixed to sturdy kevkar suspenders. Really, for testing, you know…
    Good luck! Bring it!!!

    1. I have never seen a pillion passenger on an electric unicycle but clearly it might be possible with this machine. Maybe could set a speed record for 2 person electric unicycles at anything above zero mph. The machine is quite narrow and the rear end rounded for a reason as is the fuselage to reduce sharp edges when you fall off, you learn by experience after all.

  2. Your tire appears underinflated; while a smoother ride, it’ll be twitchy and unstable. Granted, I know nothing about unicycles. Have you tried a variety of tire pressures, sizes and compounds? Those older Pilot Roads were a great tire, but technology has come a long way, and on a (uni-)bike your contact/suspension/steering is everything, but kilowatts. NB some cruiser guys even put a car tire on the back for longevity, wonder how that would handle with no rounded shoulders!

    1. If you inflate tyre properly it is almost impossible to control. It steers by tilting tyre over onto rounded shoulder so contact patch with ground is now curved, which makes you turn. Especially when learning to ride a new machine it is best to start with tyre very soft then maybe add some air from there. Tyre pressures make a big difference to control and to be honest we are still learning, there is probably an optimum compromise which we have not quite found yet. The best pressure for tarmac is probably different to that for sand as well.

      1. went to goodwood festival of speed in 2012 and saw babs and other past record holders. the most amazing vehicles I have ever seen. Going again this year. Hackaday meetup there?

        1. Took the previous model to the Blenheim Palace festival of transport, invited by the electric vehicle section of the organisers. Spent the day riding around among mainly static Tesla’s and so on. Great fun, happy to bring it to shows in the UK if anyone interested.

  3. Thoughts,

    i) The film of the first 1903 flight of the Wright brothers is pretty boring, they don’t do stunts or anything for goodness sake and they go really slow. For the pilot however it was extremely exciting flying a barely controllable machine that could have killed him at any moment. The point is that the video is documenting something and not an entertainment show.

    ii) If YT existed in 1903 and they posted a video I guarantee you that about 3% of the millions of viewers would still have given it a thumbs down, that seems to be the nature of humanity.

    iii) This is a tech geek website. You have videos and articles on how old circuit boards were designed for instance. Hardly riveting viewing for the majority of people. I find them very interesting but do accept that most of the population would not.

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