# lost part of message

The last part of my last message didn’t make it thru.

In short, I tried to post that a shock absorber would simply dissipate energy,
what I had in mind was an energy storage device, ie a spring with no damping

-> mechanism.

Mike Frankowski writes that he doesn’t see what good it would do. I’m only
conjecturing here, but what keeps me from bouncing higher is the seat limits the
amount I can drop down from standing on the pedals to compress the tire. before
jumping up.

I think the (undamped!) spring would a) allow one to drop lower by allowing the
seat to move downward and b) add a bit more oomph to the upward rebound. If I
have intuited the mechanics of hopping correctly, the rider actually pulls the
uni up, it’s not the uni pushing the rider up. This takes momentum and I think
the spring would add to it.

The tire compresses and rebounds much like a spring and someone did say “get a
bigger tire” which would help in one respect but the seat would still limit the
distance the rider could drop.

Discussion?

Dennis Kathrens

Re: internal spring in seat post; Concerning jumping higher

Dennis Kathrens writes:

>I think the (undamped!) spring would a) allow one to drop lower by allowing the
>seat to move downward and b) add a bit more oomph to the upward rebound. If I
>have intuited the mechanics of hopping correctly, the rider actually pulls the
>uni up, it’s not the uni pushing the rider up. This takes momentum and I think
>the spring would add to it.

Concerning jumping higher on a unicycle (without mechanical aids):

If one is willing to ride seat in front, one can use one’s own legs as springs
to great effect in jumping high by lowering ones’s butt down to the tire and
springing up, bringing the tire up to 24" or more off the ground. This is how
the masters of jumping do it. I don’t think a spring in the seat post would help
one jump any higher than using the above method without mechanical aids.

Just trying to say that sometimes a human can perform better without aids than
with them for particular tasks. But, please continue the discussion of the
spring and splined drive shaft etc. as it’s very interesting!

Stay on Top,

Ken Fuchs <kfuchs@winternet.com

Re: shaft drive

> But, please continue the discussion of the spring and splined drive shaft etc.
> as it’s very interesting!

Agreed! On the subject of shaft drive, I’m thinking, OK, so far, every (or
almost every) giraffe ever built had one gear ratio. And this would obviously be
easier to do in converting from a chain to a shaft drive, than also trying to
incorporate a transmission. So, for now, I want to put the idea of multiple
gears on hold, and concentrate on just the shaft drive itself.

What would be the point of converting to shaft drive? To reiterate the original
idea, it was to allow variation in the distance between crank and wheel axle
(with a splined connection between two parts of the shaft), so that bouncing on
the seat could compress a spring without changing the distance from the seat to
the pedals.

Frankly, I think that is insufficient reason to go to all the trouble of
converting to shaft drive.

However, I’m wondering, would there be some other advantages in converting to
shaft drive (without multiple gears)? I’ll list some thoughts for yer-alls’
reactions:

Shaft drive would have these advantages:

``````    *       eliminate chain stretch
*       clean up the giraffe, reducing external grease
*       look better
*       might be less vulnerable to damage when (if!) dropped
*       might make gearing changes easier (static, not on-the-fly)
*       might provide a path to multiple gears (later!)
*       can you think of others?
``````

On the other hand, shaft drive would have these disadvantages:

``````    *       requires developing the mechanism, not exactly a trivial task
*       might be heavier
*       because it's different from bicycle parts, it could cost more
*       might have problems with free play/gear lash, in other words,
slop in the transition from pushing to pulling.
*       can you think of others?
``````

I’m looking forward to people’s reactions. Is this feasible? Is it desirable?
What do you think?

>> Mark

Re: shaft drive

It seems like the drive shaft idea is getting some interest, so maybe I could
throw out another crazy idea for someone with more electrical or mechanical
engineering know-how than me…

How heavy do servo mechanisms have to be to work? (Someone’s going to shoot
me for mentioning this idea :-)) If you had the pedals and the wheel
connected by only a couple wires, you could have anything you want between
the seat and the wheel.

``    Dan (the crazy idea man)``

Re: shaft drive

> How heavy do servo mechanisms have to be to work? (Someone’s going to shoot
> me for mentioning this idea :-)) If you had the pedals and the wheel
> connected by only a couple wires, you could have anything you want between
> the seat and the wheel.
>
> Dan (the crazy idea man)

Man, you are nuts! But, yeah, if you put a spring in there, you could call it
the Boioingg (sic) Ride-By-Wire Uni! Aeronautical engineers alone would probably
buy enough just for laughs to make it worthwhile.

Or how about this? You siphon off a small amount of power from the wheel to
gradually compress a spring, then every so often, when the rider bounces down
hard, it releases a catch and fires the seat upward! The rider who gets the
most air wins.

Re: shaft drive

Hmmm… If you gonna have a servo, you can also get some of the solid state
gyroscope thingies that they use in model aircraft; and a liddle computer, and
there you are, pedaling away at a constant speed, and all the computer is gently
rocking the wheel back and forth, keeping you upright… Now lets see… There
is also strin gauges in the seat rails, so the computer can tell if you’re
leaning forward or backwards, and can drive the wheel so has to keep the
unicycle under you. So to go forwards, you lean forward, etc. Yes! The first
fly-by-wire unicycle. I love it!!! – Charles

Re: shaft drive

Why stop there? Take some of the power off into a small microcomputer designed
to auto-balance the unicycle. When the rider shoots off into the air, the
unicycle could automatically follow the rider and catch him on the way down!

And you thought I was nuts before

``````    Dan
``````

P.S. You know the scary thing about all this is that someone will probably
actually do it

From: schecter@TFS.COM (Mark Schecter) Date: Wed, 23 Nov 1994 12:36:36
-0800 (PST)
Cc: unicycling@mcs.kent.edu X-Mailer: ELM [version 2.4 PL23] Content-Type:
text Content-Length: 752

> How heavy do servo mechanisms have to be to work? (Someone’s going to shoot
> me for mentioning this idea :-)) If you had the pedals and the wheel
> connected by only a couple wires, you could have anything you want between
> the seat and the wheel.
>
> Dan (the crazy idea man)

Man, you are nuts! But, yeah, if you put a spring in there, you could call
it the Boioingg (sic) Ride-By-Wire Uni! Aeronautical engineers alone would
probably buy enough just for laughs to make it worthwhile.

Or how about this? You siphon off a small amount of power from the wheel to
gradually compress a spring, then every so often, when the rider bounces down
hard, it releases a catch and fires the seat upward! The rider who gets the
most air wins.

Re: shaft drive

>> Or how about this? You siphon off a small amount of power from the wheel to
>> gradually compress a spring, then every so often, when the rider bounces
>> down hard, it releases a catch and fires the seat upward! The rider who
>> gets the most air wins.
>
> Why stop there? Take some of the power off into a small microcomputer designed
> to auto-balance the unicycle. When the rider shoots off into the air, the
> unicycle could automatically follow the rider and catch him on the way down!
>
> And you thought I was nuts before
>
> Dan
>
> P.S. You know the scary thing about all this is that someone will probably
> actually do it

New idea for a group trick! A group of, say, six auto-giraffers ride in a
circle. Then everyone gets launched synchronously. While airborne, the unis
continue in a circle such that the riders come down on the next uni in
line, until the riders finally get back “home”. And so is born “Unicycles
juggle riders!”

Re: shaft drive

Or, save money and have two auto-giraffe’s juggle for each three riders
Folks, don’t try this at home…

From: schecter@TFS.COM (Mark Schecter) Date: Wed, 23 Nov 1994 13:54:51
-0800 (PST)
Cc: unicycling@mcs.kent.edu X-Mailer: ELM [version 2.4 PL23] Content-Type:
text Content-Length: 988

>> Or how about this? You siphon off a small amount of power from the wheel
>> to gradually compress a spring, then every so often, when the rider
>> bounces down hard, it releases a catch and fires the seat upward! The
>> rider who gets the most air wins.
>
> Why stop there? Take some of the power off into a small microcomputer
> designed to auto-balance the unicycle. When the rider shoots off into the
> air, the unicycle could automatically follow the rider and catch him on the
> way down!
>
> And you thought I was nuts before
>
> Dan
>
> P.S. You know the scary thing about all this is that someone will probably
> actually do it

New idea for a group trick! A group of, say, six auto-giraffers ride in a
circle. Then everyone gets launched synchronously. While airborne, the unis
continue in a circle such that the riders come down on the next uni in
line, until the riders finally get back “home”. And so is born “Unicycles
juggle riders!”

Re: shaft drive

>> New idea for a group trick! A group of, say, six auto-giraffers ride in a
>> circle. Then everyone gets launched synchronously. While airborne, the unis
>> continue in a circle such that the riders come down on the next uni in
>> line, until the riders finally get back “home”. And so is born "Unicycles
>> juggle riders!"
>
> Or, save money and have two auto-giraffe’s juggle for each three riders
> Folks, don’t try this at home…

To the strains of “Night on Bald Mountain,” we see “Unicycles on Parade.” Lets
just hope we don’t lose control of the situation …

New late night horror-flick: “Night of the Living Unis”. Catch it in you local
imagination …

Have a good weekend!

>> Mark