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.
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