multi geared unicycle?

My roommate and I were sitting on the porch contemplating life when I mentioned how cool it would be to have a multi geared unicycle, believing this to be impossible, unless on a giraffe, and then still impractical. My roommate, being a grad student in mechanical engineering, nonchalantly replied, “Well, you could use a planetary hub,” and then explained to me what a planetary, or internally geared hub is. Evidently, planetary hubs have been used on some bicycles for quite some time. Though I still don’t quite understand all of the inner workings of one, the jist of it is that all the gears are INSIDE the hub itself, which would naturally be the most convenient place for them to be on a unicycle. I researched a little and decided that it would be possible to create a geared unicycle, but there are some catches. First, the very center of the hub, the actual axle I guess, must remain stationary, I mean it must not turn with the rest of the wheel. On a bike you can easily attach this center rod to the frame, in fact you have to. But on a conventional unicycle, the crank arms must protrude from the center of the wheel. So, on the geared unicycle, the crank arms would have to be positioned just above the axle, with a linkage on both sides connecting them to the drivers (there would be no direct axle between the crank arms themselves). This brings us to catch #2: you would have to build a planetary hub with a driver on both sides. As far as I know, this doesn’t exist for bicycles, since bicycles only need one chain. So a conventional bike planetary hub wouldn’t do. My roommate tells me that a hub with a driver on both sides is possible. My only doubt would be whether the crank arms would remain 180 degrees to each other since they would only be connected through linkages and gears. The last catch may actually be a blessing in disguise, which is: There would be no back-pedaling on this geared unicycle, and it would have the ability to coast (with your feet on the pedals!). Now, the purist may find this appalling and unacceptable for a unicycle, but please try and see the “greener grass” or whatever. Backwards unicycling is eliminated…ok. But the point of a geared unicycle would be long distance road riding, a scenario that leaves little room for tricks anyway. Coasting without lifting your legs would also be extremely advantageous in long distance situations, and would merely necessitate the use of a brake that you could apply light pressure to in order to maintain balance. Getting on the unicycle would be a little tricky, I suppose a rolling start would be the best way. Oh, and the cable to the gear selector can easily be routed up the side of the frame, out of the way of the turning cranks. I’m sure none of this made sense. I’ve made a few rudimentary drawings, but they seem to make less sense to everyone I show them to. I was just wondering what you guys thought about this, or if anyone has thought about this before. Unfortunately, my roommate, while himself a unicyclist, claims to be too busy with his grad work to consider helping me design one. Though I don’t know…. last time I saw him he was calculating the fluid dynamics of beer spilling from its bottle. I appreciate any responses, especially from engineers with more time on their hands.

That’s impossible!


There’s one right over here.


For someone who’s just come up with the idea, you’ve put a lot of thought into it and come up with some excellent conclusions, although some are flawed. Mr. Harper will tell you in detail if you ask him nicely, I’m sure.

The principle of ‘sun and planet’ gears is easy enough, and sun and planet hub gears were fitted to ‘penny-farthing-style’ bicycles in the late 1900s. I know, I’ve ridden one. And it didn’t have a freewheel mechanism, so reversing was (theoretically) possible.

Gearing a unicycle wheel ‘up’ would be (fairly) easy for someone with the right equipment and know how (I don’t pretend I could do it, though!) but selectable gears present lots more problems. Very simply, if you need to be able to change gear, then there must be some ‘play’ in the system so the cogs can mesh and unmesh. However, for comfort and control, a unicyclist prefers no play between the movement of the cranks and the movement of the wheel.

Awesome! I figured someone had to have done it by now. I’m still reading your webpage about it, Mr. Harper. Still, is there no way to make a multi geared uni? I was actually thinking about a variation of the Sturmey Archer 3 speed hub, but you mentioned that that’s been tried before. Any plans to make a 3 speed in the future?

Re: multi geared unicycle?

Hell, I get the impression you are not a unicycle rider. If you are, you must not have tried a coasting unicycle before. To the purist, or even the average rider, the ability to back-pedal is considered somewhat essential, especially on a geared-up unicycle.

This makes for a yet more challenging engineering problem. People here and there have tackled it over the years, but I’ve yet to see a unicycle with multiple gears that can be shifted on the fly. I’m sure someone will figure it out someday though…

Note the use of paragraphs :slight_smile:

Re: Re: multi geared unicycle?

I didn’t even see ONE graph let alone a pair of graphs.

The unicycle I’m riding now is shiftable from 1:1 (29" wheel) to 1.5:1 (43.5" wheel) by moving a single bolt and a spacer. It takes about 30 seconds if I’m going for the world speed shift record but more like a minute if I’m being leisurely (like the 1970’s mens pantsuits). Frank Bonsch (the other website that Steve gave a link to) had a drawing for a two-speed with an internal shift mechanism which he hasn’t built. I think it would be difficult at best. Sturmey Archers are cog driven transmissions which simplifies matters somewhat. Having the axle stationary is quite a technical advantage. A unicycle is axle driven which places some limitations on gearing selections. Also, and very importantly, unicycles require drivetrains which can handle huge and frequent torque changes.


You, so far, have the coolest name here!

good job

Re: Re: multi geared unicycle?

Mr. Foss,
I’m a level 4 unicyclist (though not officially), just trying not to conform to any paradigms, trying to think outside the box. I realize that back pedaling is necessary even in forward motion but couldn’t you mimic the effects of back pedaling with a hand brake by applying light pressure to it? What do BMX bikers call it, feathering the brake?

Sorry my last post was paragraph deficient, I’m new to this web forum stuff. It’s pretty cool getting responses from celebrities like John Foss.

Re: Re: Re: multi geared unicycle?

Short answer: no. Longer answer, maybe, a little, with great difficulty and a lot of practice. But a multi-geared unicycle would be most useful as a touring machine. For touring, you don’t want to have intense concentration on riding for hours at a time, you generally want to cruise and enjoy the scenery.

So though a freewheeling unicycle makes for an interesting novelty cycle, I don’t think it will be useful for going places. I’m not sure if this is true or not, but I think feathering the brakes on a bike while in a wheelie has a bit of an advantage over a unicycle. Because the wheel is at the end of an extended frame, the brake action is a little more muffled than it would be on a unicycle where you’re sitting directly above the wheel’s axle.

I have a T-shirt that says Hell On Wheel. I’ve had it since around 1990 or so, and I can’t remember who made it. It was a unicycle group somewhere on the East coast, but that’s all I can remember. It has brigh orange flaming letters, as I recall, in puff ink. I have it in my “unicycle T-shirt collection” box, as I think it doesn’t fit me any more :frowning:

On Mon, 20 Jan 2003 13:45:44 -0600, harper <> wrote:

>> Note the use of paragraphs
>I didn’t even see ONE graph let alone a pair of graphs.

Harper, try reading the posts yourself instead of having them read to you.

Klaas Bil
[no sig line for forum posts]

I have them read to me by a thick-headed Dutchman because his English is so much better than mine. He wasn’t here today so I put on my thick, geezer reading glasses and tried to make sense of them on my own. I was doing OK until I read your post and wet my pants laughing out loud.

Mr. Harper, you are my hero, my new role model. We actually look similar, excepting a generation gap or two. I appreciate your insight, I’ve learned a lot today. I guess for now I’ll just be content with my 700c semcycle. One day perhaps…
-Frank Brown

OK, but no more “Mr.” Harper unless you’re making fun of me. Save the “Mr.” for “The Right-Reverend Mr. John Foss, Former President of the USA” please. He really appreciates it. You may call me Greg, like all my friends on this forum do or, as the ladies like to call me, “STOP TALKING TO ME or I’m calling the POLICE, NOW!!!”

Re: Re: multi geared unicycle?

Great Idea Hell on Wheels! Yes, a freewheeling unicycle with practice would be extremely effective if used in conjunction with feather brakes. Go for it!! With practice, while on flat terrain I suspect one would become proficient enough that the brake would rarely be used. Most of the benefit of freewheeling would be on down hills or whenever one needed a rest from pedaling. I will go out on a limb and say the right set up would prove superior to any over the road unicycle you see today, provided the use of the internally geared hub is not sacrificed. Mechanically, I don’t know if it’s possible, but if so it would be one efficient machine for over the road travel.

Remember, it was not too long ago that geared unicycles, internal or otherwise, were said to have been “unworthy of building”. Gear backlash, coupled with the increase in inches of travel per revolution, were said to be too hard to balance and therefore inefficient.

I have said before and I’ll say it again—if Harper’s hub becomes available and affordable to the masses, nothing in the past, or future, will equal its significance in the sport of speed and distance unicycling. The hub provides a huge leap in the way of speed and efficiency compared to big wheels we are riding now. The development ultimately brings a new level of “fun” to our sport.

I am looking forward to the day when we are all riding multi-geared unicycles that can shift on the fly, and YES freewheel.

We are witnessing the unicycle evolve. With regard to technology, we are where the bicycle was 100 years ago. We have a lot of evolving to look forward to! I have long been waiting for the one-wheeled "high-end "bicycle to become a reality. As long as there remains a few innovators that like Harper that refuse to let nay-sayers stand in the way of dreams and progress, the reality is within my pedaling lifetime. And I am WAY excited!


Re: Re: Re: Re: multi geared unicycle?

Gee, Mr. Foss, I always thought you were the nice guy on the forum, but you seem pretty cranky in this thread.

First, you accuse hell-on-wheel of not being a unicyclist, and then, after he informs you that he’s an unofficial Level 4, rather than apologize, you go and poop on the praise he’s received for his cool username by telling him it’s not original at all.

There’s nothing cool about getting condescending responses from celebrities.


Re: multi geared unicycle?

On Mon, 20 Jan 2003 10:33:25 -0600, harper
<> wrote:

>There’s one right over here.
>harper - Pavement Victim
> -Greg Harper

My one is in my car…

By the way: i think it is possible to build a continuously variable
transmission hub for a unicycle with a ratio range of perhaps
0.7…1.6. But the parts are very difficut to machine (complex
geometry and must be hardened). But it is possible without belts! Only
rigid parts and it works in both directions.

Sorry that I can´t tell details but I have talked to one who wants to
build the mechanisms for other applications (he has the patents on
this machanism) and he said when the production has started (about
2004) we could think about a prototype… :wink:

Another thing: has it ever been possible to ride a unicycle in a city
marathon officially? It is planned for the Duesseldorf marathon
(Germany, 4. may 2003) to have some unicyclists riding. Categories: 24
inch, 114mm cranks; 28 inch 114mm cranks and unlimited. Has anybody
ridden an official marathon on a uni?

unifrank (Frank Bonsch)

>I have long been waiting for the one-wheeled "high-end "bicycle to become a reality.


now who’s unicyclist credentials are in doubt?

Re: Re: multi geared unicycle?

That’s ok for Mr. Foss, someone has to fill that role.

I think I’ve heard about people doing it. I’ve unoffically ridden in the past two Richmond Marathons, and offically rode in the last Richmond 40 mile MS bike tour. I’m hoping to do the two day 150 miler this May (unless someone tells me it’s not possible, in which case I’ll go sit in a corner, huddled in a fetal position, repeating to myself what a failure my life has been).

I guess that’s why I’m so interested in the multi geared coasting unicycle. It would rock to be able to really compete with bikes.