beast of a geared hub

Hey Jogi – do you have any plans or diagrams you use to build it? I would love to try to copy your design and make one. I have a basic machine shop (non CNC) in my garage, and I’ve been really interested in getting into geared unicycle design. Harper sent me some of his hub drawings, and I hope to eventually try to make one of his hubs too.


I understand now, to make it faster the inside ring must be fixed, this then boosts the orbitting ‘planets’ to turn the outter ring.

Juggleaddict, if it was the way you say it would make it easier to pedal i.e one rotation pedalling would turn rotate the wheel 0.75 or 0.5 times. I suppose it would be possible to gear and machine it in such a way that one can switch it around to do both.
I might look into and see what the possibilites are and the logistics, but I would never be able to make one.

Epicyclic gearing is used here to increase output speed. The planet gear carrier (green) is driven by an input torque. The sun gear (yellow) provides the output torque, while the ring gear (red) is fixed. Note the red marks both before and after the input drive is rotated 45° clockwise.

. . . this is taken directly from the wiki article. outter ring is fixed. . . inner ring is output . . . this increases speed. I’m pretty sure I’m right. : |

Perhaps you are both correct then, if either of them are fixed it will increase the output speed. If the outter ring is the ring fixed to the wheel it will also create more speed so long as the inner ring is fixed!

How about a fixed gear with off the shelf parts?

there would be some metal fab and welding of the frame, but no real machining. there is an example of one on youtube and a sick version Seen on this forum that’s red with carbon cranks and a disk brake… but you can pick up the unicycle profile crank and spindle, use the profile DH front mountain bike hub, a cog that fits the hub like a 6 bolt rotor and use a profile trials sprocket…

. . . this is hurting my head :’(

Yes, Wired, I’m pretty sure you’re right, either way will work. . . now that I’ve thoroughly read every word of the wiki article n.n’

I’m now need chocolate . . .

so, basically if you want to gear down, you would either
a.) if the outter gear is fixed, the sun would be the input and the planetary gears are the output.
b.) if the sun is fixed, the outter ring would be the input and the planetary gears are the output.

head hurts

maybe I should make a Autocad file that has all of the scenarios of fixed vs free, and just post the file. I’m surprised at how confusing some of these articles can be when trying to explain this. I think it’s just one of those things that’s much easier to understand if you saw it work for 2 seconds.

I know what you mean, perhaps its time for bed <rubs head>

Yes, you can hold either the sun or the ring still and drive the planets to gear up. Jogi’s hub in this thread definitely has the sun (middle gear) held still - it’s bolted to the bearing cap.

I think in his previous one (2.5:1 gearing I think) the outer ring was still and the sun drove the hub.


Jogi that is a fantastic bit of engineering,I was wondering if you cut the gears yourself or do you mix and match parts from somewhere else.If you make the gears yourself what grade steel do you use.


Damn… you’re bad guys… you’ve made me think how to build a guni myself. And instead of working today I’m drawing gears :wink:

I was doodleing all last night to see what I could come up with! No chance I could build it, but def worth a try!

Yes Rob got it right!

At the first one with the 2.5 ratio the ring was fixed, but at this one is the sun fixed.

@ Corbin
send me a mailadress to and I ´ll send the plans:)

sorry for short response but I am on the road the last days…

Cheers Jogi

I draw a geared hub last year in one of my class, but with no mesurement but I know how it works! One day it’ll be cool if I could built one:)

Where do you see threads? :thinking:

And with my luck, I’d have a pant leg get hung in there and not a pebble which equals having the uni land on you along with the other carnage. Then you have to rely on passer by to cut you loose :o