Pedals on Axle geared Uni

Has this been made? I just had a thought…

If you use a bike hub, it has a gear attached to it, and an axle going through the middle. Say Attached to that axle you had another gear, and cranks. Use a fork setup sort of like this Instead of cranks coming out up high on the fork, have a gear.


          _     _
Gear --> |_|---|_| <-- Gear
          |  ^  |
          |  H  |
Chain --> |  U  | <-- Chain
          |  B  |
          |     | 
Gear --> |_|---|_|---
             ^  ^  ^   
             A  G  W
             x  E  H  
             L  A  E
             E  R  E
                   L
                   
                   H
                   U
                   B

The fork goes down through the hub and axle. The cranks would be to the left of the far left gear. The cranks on the main axle would make it better for hopping, I think.

e39m5

does this idea atleast make sense to you? If not im might try and build it out of knex. It’s hard to explain.

e39m5

Isn’t Purple Phaze an improvement on that design.

Purple Phaze is now called “Outta Phaze” and available through LiveWire unicycles. LiveWire

It actually seems to be the same design I was thinking about. I just had nother thought. Say both sides of the wheel were geared. However, they were geared differently and you could somehow engage and disengage the gears attached to the crank or hub. Possibly a 2-Speed Unicycle.

e39m5

There have been many threads on geared unicycles. A search will give you much reading material.

Now that’s a thought. It could work. It would certainly complicate the design which adds cost. Figuring out how to securely lock one side while letting the other side run free would be tricky while still allowing it to shift. I don’t see it being able to shift on the fly, but being able to manually move a few locking pins around to shift to the other gear would be cool.

Has anyone ever heard of a way to disengage a gear from an axle?

e39m5

The Schlumpf hub has a way to engage and disengage a fixed gear.

There is a hand modified 3 speed hub that is turned into a shiftable 2 speed fixed gear hub. But the guts of that hub wouldn’t stand up to unicycle forces.

Other than that, I’m not aware of any fixed gear bike hubs that can engage and disengage a fixed gear. Doesn’t mean it’s not possible.

The jack shaft gearing (as on the Purple Phaze and Outa Phaze) would require a unique method for engaging and disengaging the gears if it was to be made shiftable.

schlumpf is all internal, right? Im trying to think of a way to do it like a clutch in a car. But im not sure exactly how they work. Theres a way to do everything, or almost everyhing, but how do we do this.

e39m5

The Schlumpf is internal, but the same idea could be applied to a gear external to the hub. It’s six or so dowels or pins that engage holes in a ring. Have the dowels engage an external cog or cog supporting structure and you could engage and disengage a cog gear. So there are ways to do it that should theoretically work.

The problem with most clutches is that they tend to work on friction so they allow some slippage. You don’t want slippage in a unicycle drivetrain.

[B]Say both sides of the wheel were geared. However, they were geared differently and you could somehow engage and disengage the gears attached to the crank or hub. Possibly a 2-Speed Unicycle.
e39m5{/B]

Well, well, well! Yet another idea with potential!

Here’s how one might address the double-sided jackshaft issue (this off the top of my head):
With a Phaze-type transmission on both sides, on the left side, you’d have the lower gear ratio. Replace the chainring and the left crank arm with a front freewheel crank arm. Install a single-speed freewheel on this crank arm. Thus, the left side gearing would only engage when you are in the lower gear.
When a higher gear is selected, and the hub turns faster over the axle than the low gear cadence, this would cause the left freewheel to spin (due to the fixed hub and jackshaft apparatus being driven by the higher gear on the right side), and the left side would thus be freewheeling and not driving the hub at that time. (Are you with me on this?) The only time the lower gear could drive the wheel is if the higher gear is disengaged.

But to engage the higher gear on the right side (to override the lower geared left side), you’d have to use a pin mechanism to lock or unlock the higher gear ratio. This can be done on one of the jackshaft cogs by a trigger mechanism on the inside of the housing that when pressed in, could release the jackshaft. Hey, it’s only one pin to deal with, not two.

What do you think of this 1-minute idea??

So… Both jackshafts will always be spinning, but only one will be drving the hub. Did I get that part right?

You seem to have a pretty good understanding on how you would change gears, but I didn’t really understand it.

Some questions:
When the left jackshaft is driving, what gear on the right is disengaged? Well it be the same the other way around?

How would a couple a pin stand up to the forces on the unicycle?

e39m5

Re: Pedals on Axle geared Uni

On Sat, 21 May 2005 13:24:06 -0500, “S_Wallis” wrote:

>Purple Phaze is now called “Outta Phaze” and available through LiveWire
>unicycles. ‘LiveWire’ (http://www.livewireunicycles.com/)

Isn’t rather “Purple Phaze” the original prototype and “Outta Phaze”
the production model based on it?

Klaas Bil - Newsgroup Addict

wouldnt you be grumpy if somone just said you had PMS? - jagur

Yup.

The disengagement of the lower gear ratio automatically occurs when the higher gear kicks in. Once the higher gear begins driving the hub, the lower gear side will freewheel, because the hub is now spinning faster than the low gear ratio itself.

Think 1/4" steel plugs. Or a miniature clutch drive in the jackshaft itself. The forces on the drivetrain are alf that of direct drive, because the power is transmitted through 2 halves (sides) of each jackshaft.
I’d love to work more on this, but ideas for a multi-speed shiftable drivetrain are jellin’…

Re: Re: Pedals on Axle geared Uni

Yes, your wording is much more accurate than mine.
I meant that the concept was renamed, not the unicycle itself. Following the link made it clear, but thanks for pointing out my mistake. I will return the favor if you ever make one.:wink:

Scott

What would happen if you tried to pedal backwards or roll the unicycle backwards to get the pedals into position for mounting? Granted, you don’t pedal a Coker backwards much. But everyone does it a little bit at least occasionally.

The double sided jackshaft with two different gear ratios is probably the most promising way of getting two different gear ratios to work on that style of unicycle. Trying to figure out how to engage and disengage each side is the tricky part. And then the issue that you’ll probably need a custom machined hub.

What would we do without you, JC?
I should have left this thread alone after Chrashing’s auspicious post!