This Monowheel Is Bright Orange, And We Want One

Monowheels are a singular form of transport. Like electric scooters and the Segway, they are remarkably impractical for getting from point A to point B, are expensive to build or buy, and make you look faintly silly as you ride them down the street. However, we’d be hard pressed to find a member of the Hackaday team that wouldn’t at least want a go on one for half an hour. [MakeItExtreme] felt the same way, and built one of their own.

The build starts with a tube bender, used to form 40mm tubing into a continuous circle to form the main wheel. Teflon is then turned to produce several rollers that interface the main wheel to the inner frame. Several small motorbike tyres were cut apart to create the tread to provide some decent grip. Power comes courtesy of a 110cc four stroke engine, allowing this thing to go just fast enough to get the rider seriously injured in the event of an accident. The team reports stability is poor at low speed, but remarkably good once above 30 km/h.

The team did a great job, and we particularly enjoy the bright orange paint scheme and fetching decals that really finish it off well. The monowheel concept is remarkably similar to the diwheel, which we’ve seen applied to old Fords with somewhat terrifying results. Video after the break.

23 thoughts on “This Monowheel Is Bright Orange, And We Want One

  1. My shade tree mechanic friend likes to observe the most important control in operating a moving vehicle is the brake. Steering comes in a close second.

    This crazy contraption offers neither of these controls! Lots of foot-dragging for both operations.

    No faulting the execution or design. Just trying to highlight the unconventional nature of the vehicle. It would be funny to see what happens if someone just grabs the outer ‘wheel’ while the driver tries to accelerate. I assume because of the ICE, it will stall once the driver becomes inverted, but perhaps centrifugal force would keep the engine going….

    1. Tell your friend he’s wrong, steering is the most important control on a land vehicle and the brake is the second most important…and it’s not exactly a close second either.

      When you’re driving, imagine losing one of these at random points. If you lose steering, you could go straight off in a turn or be guided by the road surface into an essentially random direction. You could crash into any number of stationary or oncoming objects, even ones that are very close to the current vehicle position. If you lose brakes, you may be able to bleed off speed or dodge objects with the steering, or at the very least you can choose what you crash into – like some thick brush or a parked car instead of an oncoming car or a large tree or a crowd.

      1. I think you’re mistaken, brakes are more important than steering. Imagine trying to take a sharp turn at high speeds…things get dicey. Conversely I’d you lose steering at high speeds, regardless of your direction brakes would allow a safer crash.

        What’s worse, losing steering and slamming on the brakes, ending in a 30mph crash or losing brakes, jumping the curb and rolling the vechile trying to swerve out of the way?

        1. The difference lies in the aggressiveness of a maneuver vs. braking. You change your trajectory more aggressively by turning than by braking in high speeds, and avoiding collision is thus easier by changing direction than by stopping. Therefore, from this POV, maneuverability becomes more important than brakes with increasing speed.
          However, brakes are more important than an engine. You CAN speed up, but if you can’t turn, you will need to stop eventually.
          There’s an old saying that helps you tell good vehicles from bad.
          A good vehicle has the carriage (chassis + suspension + tyres) faster (capable of safely handling higher speeds) than its engine, and brakes faster than the carriage.
          But a good driver won’t let his vehicle take him to a place where his mind hasn’t been 5+ seconds earlier.

    2. ‘Didn’t realize there were no brakes, though I think it’d be of little help since, unless applied sparingly and slowly, hard braking would just result in the driver being thrown out of the device as momentum would keep the wheel moving.

      Was surprised at the lack of protective clothing. A tank top? Really?

    3. The Brake functions exactly as it would on any other wheeled vehicle. Your stopping power is completely dictated by how much mass you can muster behind the contact patch, which, although very small here, carries the entire weight of the vehicle, and unlike a multi wheeled vehicle, it does not lose any of it’s contact force due to rear wheels being lightened as the center of mass tries to rotate up and forward, so the friction area is consistent through the whole deceleration. In fact, unlike multi wheeled vehicles, a portion of the mass actually shifts rearward of the contact patch when you engage the brake, as the rear portion rotates upward. Naturally, the best design should allow you to shift your body weight into a full crouch as the mass of the motor and frame start to rotate. It’s a delicate balancing act between pressure on the brake and adjusting your crouch. As long as you can muster the skill, it’s just a fight between you, gravity, and momentum. If you manage to do a full loop, just remember, you would have done the same on a motorcycle of the same mass, just not as pleasantly, assuming you manage to maintain your riding position. The motorcycle just won’t roll as far, shedding it’s energy by body and frame impacts with the ground and losing mass as it goes. You, on the other hand get to endure rag doll physics and will come to a stop a little quicker, hopefully without shedding much mass. (Been there a few times, essential learning experience)
      This is a relatively small motored machine, so you have the advantage of shiftable body mass, although the hoop is a bit cramped for much in the way of gymnastics, and I would have gone for a more foot forward riding position to maximize useful body travel, but it’s also never going to go terribly fast to begin with.

    4. As with any vehicle, there’s the inherent design, and then there’s the person operating it.

      At one Bay Area Maker Faire, I witnessed the following: crowds of the public lined up in the morning to enter the fair from the back entrance, where exhibitors also entered. Rolling up comes a guy on one of these monowheels… finally stopping VERY close to the crowd line.

      A bunch of staff come up to him and essentially say, “Look buddy, we warned you last time about that thing. You can’t go rolling around with large crowds around. We’re not letting you in unless you get off and walk it in, and we’re thinking about not letting you in at all.”

  2. Couple of thoughts. First: could you use a spinning flywheel oriented horizontally at the bottom of the frame to help with slow speed stability? Second: could you steer with a change in cg in a similar manner to the Swincar. In this case rotating the handle bars pivots the rider to the side for steering?

  3. I think on a bike, the fork-angle provides the low speed stability. The line joining the points where the wheels touch only contains the center of mass when pointed straight ahead. When you turn the wheel left, the center of mass shifts right of the line. So, turning towards the direction of fall can rebalance. The amount depends on the fork angle and front wheel radius. If the fork is vertical, you fall over.

    That is missing on these mono-wheels. Leaning left or right does not make you turn on the mono-wheel like it does on a bike.
    Plus, the lower the CG, the faster it falls over. A tall unicycle can be controlled because of the lag due to momentum and the length of the lever from the ground to the seat. Try it with a pencil versus a meter stick. (You DO have a meter stick?)

    (I’m risking exposure here as a BS’er by talking of the top. Since the bicycle has been thoroughly explored by physics and engineering today.)

    1. Yes, fork angle inhibits or promotes castering depending on the angle and your explanation of counter steering is correct. Steering on this vehicle is dependent entirely on the ability of the rider to lean the wheel in the direction of intended travel, allowing the wheel to follow it’s own natural curve, which is enhanced by curved cross section. Unfortunately this tall narrow wheel is never going to turn very tightly through leaning alone unless the rider becomes very skilled at maintaining his balance through delicate throttle control and leaning at an extremely low angle. Picture a coin as it spins on the table and reaches that final motion where it’s just wobbling around on it’s rim. That’s the type of motion you’d have to master. You could theoretically make a tighter turn than a two wheeled vehicle, in as little as the diameter of your own wheel, providing you can shift any protruding parts far enough towards the high side to keep from scraping the ground. But your skill levels would have to be that of a trials rider combined with that of a circus acrobat!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.