Unicycle Given a Hand Crafted Gear Box

Being able to coast on a bicycle is a feature that is often taken for granted. The use of a freewheel was an improvement made early in the bicycle’s history, for obvious reasons. This also unlocked the ability to build bikes with multiple gears, allowing higher speeds to be easily reached. On a unicycle, however, there’s no chain and the pedals are permanently fixed to the wheel’s axle, meaning that there is (usually) no freewheel and no gearing. [johnybondo] wanted to get some more speed out of his unicycle, though, and realized he could do this with his own homemade internal geared hub for his unicycle.

The internal hub gear was machined and welded by hand as a one-off prototype. There are commercial offerings, but at $1700 it’s almost best to fund your own machine shop. It uses a planet gearset which is more compact than a standard gear, allowing it to fit in the axle. Once all the machining was done, it was time to assemble all of the gears into the hub, lace it to the wheel with spokes, and start pedaling away. Since it was so successful, he plans to build another and lace it to a larger wheel which will allow him to reach even higher speeds. If this isn’t fast enough for you, personally, there are other options available for ludicrous speed.

Now, this gear is still “fixed” in the sense that it’s a permanent gear ratio for his unicycle and it doesn’t allow him to shift gears or coast. There’s no freewheel mechanism so the unicycle can still be pedaled forward and backwards like a traditional unicycle. The advantage of this setup is that the wheel spins 1.5 times for every one revolution of the pedals, allowing him to more easily reach higher speeds.

12 thoughts on “Unicycle Given a Hand Crafted Gear Box

  1. I understand the balance required, over the period of perhaps a second, for a gentle seamless shift to occur… but one speed? Same as an elevated uni w a chain and alterable sprockets. SF Pier 39, ButterflyMan… catching this?

    1. There is a multi-speed commercially available unicycle hub made by schlumpf innovations that allows for shifting between 1:1 and 1:1.5 gearing. The geared hub is far ideal to a ‘tall’ unicycle (known as a penguin giraffe in the community) because you’re lower to the ground and it’s far, far less awkward to ride, which matters when you’re looking at speeds up to 40km/hr (and faster, for some of the world’s best!)

      I would really like to see something like the schlumpf with a higher gear ratio at the high end though – typically I like to ride a 700c road tire instead of a 36 to commute, purely due to how absolutely giant the 36 is in the city, but when racing I just can’t keep up with the geared 36 crowd ;)

      Super cool to see unicycle stuff here though! Perhaps one day I’ll have access to the machines required to make similarly cool toys.

    1. A 36″ is *much* harder to transport. A 24″ can be easily put into a trunk or back seat of any economy car, or carried onto public transportation or into a classroom or office, it’s not nearly so for a 36’r.

    1. I don’t think you want it to (ever) freewheel on a unicycle. Deceleration (and just plain balancing) under control requires being able to apply torque in the reverse direction.

      1. BBJ is correct, you need the ability to back-torque to maintain balance. There are tricks – pedal with one foot and use the other shoe on the wheel as a brake. Or if your unicycle has a brake (common on mountain unis), you can use that. But it’s super sketchy in either case for general riding.

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