# Epicyclic Hubs

Harper,

Truly some lovely work there in your hub design, something does tickle me about the epicyclic gear system, and thanks also for documenting it all so clearly for all to see…

Anyway, some time ago i was thinking obout the idea of a geared unicycle, and in my searching around [1], discovered some details about a guy who doctored an older style Sturmey Archer 3 speed hub to carry out a similar role. Has anyone ever heard of this? Sounds like the next step to me, not only an increased gear ratio, but a choice of 3 speeds!

Also, reading your little blurb on the technical problems of the hub, I dont think there will be a reaction from the hub to twist the unicycle as you ride simply due to the presence of the sun gear assemly tab on the right side of the frame. All moments in that plane will equate to zero and the uni will steer as a normal hub would. (The statics in that plane will remain the same). you probably will see that some fore - aft force is felt however…

I guess that the only way to tell is to take it for a ride! any chance of a tour down under?

Mikey
[1] on the web so it MUST be true!

One of my dreams has always been to visit the northeast coast of Queensland. You’re a bit south of there.

You may have a point about the torques about the seatpost axis. I haven’t written down the force and torque balance equations or made the diagrams. It just seemed to me that all of the torque is applied to the right fork causing it to want to rotate in the direction pedaled. Then I thought that the top of the right fork, trying to rotate forward, would exert a torque about the seatpost axis. If you draw the balance diagram, tell me who’s right.

I think there are threads from some time ago describing experiences modifying SA hubs. As I recall, the SA gears are kind of wimpy for the stresses imposed by quickly changing direction. This would include quickly slowing down which they don’t have to handle…they freewheel while the brakes do the work. I also think it would be kind of flaky trying to modify something designed for a different drive scheme.

The idea of multiple gears still has some appeal but the idea of direct drive, shift-on-the-fly hubs for a unicycle I think is unworkable. Don’t get me wrong, I think it could be built, I just don’t think it could be ridden. It’s a face-plant waiting to happen. Missing a shift or jamming gears, guess what’s going to happen.

sturmy did at one time make a 3 spd fixed hub

they are hard to find and very expensive,i doubt the hub could be converted for uni but the idea may birth some brainstorm in a secret labrotory someday

The Bike Smith in Seattle, Washington USA can modify a three speed coaster hub to a two speed fixed gear hub. It’s a bicycle hub and would not work on a standard unicycle. If used on a unicycle it would need to be on a giraffe.

I have ridden a bike with the two speed fixed gear hub. I liked it. I want one. When I get a place with a garage and more place to store toys I will get one. If I remember right the two gears are at a ratio of 1.0 and 1.2something. If put on a giraffe it would be very challenging to change gears while moving. The change in gear ratio and the slight delay while the gear changes would likely make it difficult to stay on the unicycle.

john_childs

On Tue, 5 Feb 2002 03:36:29 +0000 (UTC), harper
<forum.member@unicyclist.com> wrote:

>The idea of multiple gears still has
>some appeal but the idea of direct drive, shift-on-the-fly hubs for a
>unicycle I think is unworkable. Don’t get me wrong, I think it could
>be built, I just don’t think it could be ridden. It’s a face-plant
>waiting to happen. Missing a shift or jamming gears, guess what’s
>going to happen.
For shift-on-the-fly then, would there be any value in the concept of
a continuously variable transmission? It might also be possible to
make it shift automatically and gradually, but then self-contained (no
access from outside needed).

## Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“PATCH, SGC, CQB”

A stepless variable transmission comes to mind… I think I saw a bicycle built that way, called the
Autobike, using centrifugal weights attached to the spokes to move whatever mechanism was necessary. I don’t
know if it was actually a stepless variable setup though, it may have actually shifted gears, albeit
automatically according to speed.

John

Klaas Bil wrote:

> On Tue, 5 Feb 2002 03:36:29 +0000 (UTC), harper
> <forum.member@unicyclist.com> wrote:
>
> >The idea of multiple gears still has
> >some appeal but the idea of direct drive, shift-on-the-fly hubs for a
> >unicycle I think is unworkable. Don’t get me wrong, I think it could
> >be built, I just don’t think it could be ridden. It’s a face-plant
> >waiting to happen. Missing a shift or jamming gears, guess what’s
> >going to happen.
> For shift-on-the-fly then, would there be any value in the concept of
> a continuously variable transmission? It might also be possible to
> make it shift automatically and gradually, but then self-contained (no
> access from outside needed).
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “PATCH, SGC, CQB”

the auto bike was a total peice of sh…crap

it was not stepless.the weights on the wheel though speed excellerated expantion shifted the chain,there were still steps from toothed cog,to toothed cog…and so forth…

Sounds chunky…

I was thinking of a belt drive with pulleys that would change diameter,
like a snowmobile.

John

jagur wrote:

> the auto bike was a total peice of sh…crap
>
> it was not
> stepless.the weights on the wheel though speed excellerated expantion
> shifted the chain,there were still steps from toothed cog,to toothed
> cog…and so forth…
>
> –
> jagur
> Posted via the Unicyclist Community - http://unicyclist.com/forums

On Wed, 06 Feb 2002 18:41:06 GMT, John Zanetti <gianniz80@yahoo.com>
wrote:

>
> Sounds chunky…
>
> I was thinking of a belt drive with pulleys that would change diameter,
>like a snowmobile.
That does exist for cars (Dutch invention BTW). The latest and
greatest is a belt (metal links) with push action rather than pull,
which implies less power loss. Of course for a HPV like a uni is, we
need a lot smaller version which may not exist yet.

## Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“INFOSEC, George Tenet, subversives”

On Wed, 06 Feb 2002 18:41:06 GMT, John Zanetti <gianniz80@yahoo.com>
wrote:

>
> Sounds chunky…
>
> I was thinking of a belt drive with pulleys that would change diameter,
>like a snowmobile.
That does exist for cars (Dutch invention BTW). The latest and
greatest is a belt (metal links) with push action rather than pull,
which implies less power loss. Of course for a HPV like a uni is, we
need a lot smaller version which may not exist yet.

## Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“INFOSEC, George Tenet, subversives”

On Wed, 6 Feb 2002 09:16:37 +0000 (UTC), jagur
<forum.member@unicyclist.com> wrote:

>the auto bike was a total peice of sh…crap

>

>it was not
>stepless.the weights on the wheel though speed excellerated expantion
>shifted the chain,there were still steps from toothed cog,to toothed
>cog…and so forth…
For bike use, that doesn’t sound crappy (or unusual, for that matter)
to me. Bud admittedly for a uni it’s less ideal, let’s say.

## Klaas Bil

“To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
“INFOSEC, George Tenet, subversives”

I didn’t realize that the Dutch invented that. Interesting.
Didn’t Honda make a Civic using that type of drive? The Civic HX.

John

Klaas Bil wrote:

> On Wed, 06 Feb 2002 18:41:06 GMT, John Zanetti <gianniz80@yahoo.com>
> wrote:
>
> >
> > Sounds chunky…
> >
> > I was thinking of a belt drive with pulleys that would change diameter,
> >like a snowmobile.
> That does exist for cars (Dutch invention BTW). The latest and
> greatest is a belt (metal links) with push action rather than pull,
> which implies less power loss. Of course for a HPV like a uni is, we
> need a lot smaller version which may not exist yet.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

I didn’t realize that the Dutch invented that. Interesting.
Didn’t Honda make a Civic using that type of drive? The Civic HX.

John

Klaas Bil wrote:

> On Wed, 06 Feb 2002 18:41:06 GMT, John Zanetti <gianniz80@yahoo.com>
> wrote:
>
> >
> > Sounds chunky…
> >
> > I was thinking of a belt drive with pulleys that would change diameter,
> >like a snowmobile.
> That does exist for cars (Dutch invention BTW). The latest and
> greatest is a belt (metal links) with push action rather than pull,
> which implies less power loss. Of course for a HPV like a uni is, we
> need a lot smaller version which may not exist yet.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

I didn’t realize that the Dutch invented that. Interesting.
Didn’t Honda make a Civic using that type of drive? The Civic HX.

John

Klaas Bil wrote:

> On Wed, 06 Feb 2002 18:41:06 GMT, John Zanetti <gianniz80@yahoo.com>
> wrote:
>
> >
> > Sounds chunky…
> >
> > I was thinking of a belt drive with pulleys that would change diameter,
> >like a snowmobile.
> That does exist for cars (Dutch invention BTW). The latest and
> greatest is a belt (metal links) with push action rather than pull,
> which implies less power loss. Of course for a HPV like a uni is, we
> need a lot smaller version which may not exist yet.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

I wonder if there’s a way to not use belts, but have some type of constant-variable transmission built
into a hub… THat would be wild. It would revolutionize bicycling and unicycling as we know it. There
could be a control to adjust the sensitivity of it, or some ability to hold it at a certain ratio. Hmm…

John

Klaas Bil wrote:

> On Wed, 6 Feb 2002 09:16:37 +0000 (UTC), jagur
> <forum.member@unicyclist.com> wrote:
>
> >the auto bike was a total peice of sh…crap
>
> >
>
> >it was not
> >stepless.the weights on the wheel though speed excellerated expantion
> >shifted the chain,there were still steps from toothed cog,to toothed
> >cog…and so forth…
> For bike use, that doesn’t sound crappy (or unusual, for that matter)
> to me. Bud admittedly for a uni it’s less ideal, let’s say.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

I wonder if there’s a way to not use belts, but have some type of constant-variable transmission built
into a hub… THat would be wild. It would revolutionize bicycling and unicycling as we know it. There
could be a control to adjust the sensitivity of it, or some ability to hold it at a certain ratio. Hmm…

John

Klaas Bil wrote:

> On Wed, 6 Feb 2002 09:16:37 +0000 (UTC), jagur
> <forum.member@unicyclist.com> wrote:
>
> >the auto bike was a total peice of sh…crap
>
> >
>
> >it was not
> >stepless.the weights on the wheel though speed excellerated expantion
> >shifted the chain,there were still steps from toothed cog,to toothed
> >cog…and so forth…
> For bike use, that doesn’t sound crappy (or unusual, for that matter)
> to me. Bud admittedly for a uni it’s less ideal, let’s say.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

You know what else… I was thinking about missed shifts, but aren’t those types of hub able to be shifted
while sitting still? People would still try to shift them while moving, but the more safety-conscious would
be able to choose the gear ratio before they start riding, no?

John

Klaas Bil wrote:

> On Wed, 6 Feb 2002 09:16:37 +0000 (UTC), jagur
> <forum.member@unicyclist.com> wrote:
>
> >the auto bike was a total peice of sh…crap
>
> >
>
> >it was not
> >stepless.the weights on the wheel though speed excellerated expantion
> >shifted the chain,there were still steps from toothed cog,to toothed
> >cog…and so forth…
> For bike use, that doesn’t sound crappy (or unusual, for that matter)
> to me. Bud admittedly for a uni it’s less ideal, let’s say.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

You know what else… I was thinking about missed shifts, but aren’t those types of hub able to be shifted
while sitting still? People would still try to shift them while moving, but the more safety-conscious would
be able to choose the gear ratio before they start riding, no?

John

Klaas Bil wrote:

> On Wed, 6 Feb 2002 09:16:37 +0000 (UTC), jagur
> <forum.member@unicyclist.com> wrote:
>
> >the auto bike was a total peice of sh…crap
>
> >
>
> >it was not
> >stepless.the weights on the wheel though speed excellerated expantion
> >shifted the chain,there were still steps from toothed cog,to toothed
> >cog…and so forth…
> For bike use, that doesn’t sound crappy (or unusual, for that matter)
> to me. Bud admittedly for a uni it’s less ideal, let’s say.
>
> Klaas Bil
> –
> “To trigger/fool/saturate/overload Echelon, the following has been picked automagically from a database:”
> “INFOSEC, George Tenet, subversives”

In article <3C6216B4.324734CC@yahoo.com>,
John Zanetti <gianniz80@yahoo.com> wrote:
)
) I wonder if there’s a way to not use belts, but have some type of
)constant-variable transmission built
)into a hub… THat would be wild. It would revolutionize bicycling and
)unicycling as we know it. There
)could be a control to adjust the sensitivity of it, or some ability to
)hold it at a certain ratio. Hmm…

In article <3C6216B4.324734CC@yahoo.com>,
John Zanetti <gianniz80@yahoo.com> wrote:
)
) I wonder if there’s a way to not use belts, but have some type of
)constant-variable transmission built
)into a hub… THat would be wild. It would revolutionize bicycling and
)unicycling as we know it. There
)could be a control to adjust the sensitivity of it, or some ability to
)hold it at a certain ratio. Hmm…