Suspension MUni



I like the idea of having the bands arranged as spokes,
because it would undoubtedly be a lot lighter, and probably
cheaper, but I can see that the rim would move side to side
a lot as well.

John, hope the exam went well.

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Ken Cline wrote:
> *"Rayden"
> <[email protected]> writes:
>
> > Ok here is a question. Shock absorber versus spring. We
> > have all
> been
> > assuming shocks would be better but why? There has to be
> > a reason.
> Of
> > course we could build a protype of each and see but I
> > dont think
> that is
> > going to happen.
>
> I don't think dampers are a good idea. First, after
> compression during a drop, dampers would tend to make the
> wheel roll unevenly (eccentrically). Second, work dont on
> the damper would be wasted energy.
>
> Ken *

If you have a spring you need some kind of damper i think.
If not you would just bounce forever. Possibly your legs
would do the dampening and you wouldn't need them. I think
this is getting to the point where the answers will only
come from building one and testing.

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Ken Cline wrote:
> * ... Second, work dont on the damper would be
> wasted energy.
>
> Ken *

This arguement is used against using suspension in mountain
biking but I know from my own experience and from the racing
world that overall it saves energy.

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Right, firstly Rayden the amount of time you put into all
your wonderful diagrams is admirable, and the ideas behind
them bloddy excellent. I was just thinking, if the uni would
only be good for dropping etc as said before somewhere
wouldnt it be easier to make suspension cranks- like semi
bendy ones. I realise that a suspension seatpost would be
nesecarry otherwise there goes fathers day. Well my ideas
from the land of ignorance, Keep up the awesome work, Mark

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Ken Cline wrote:
> *First, after compression during a drop, dampers would
> tend to make the wheel roll unevenly (eccentrically).
> Second, work dont on the damper would be wasted energy.*
It wouldn't be a huge amount of damping. If it was just a
spring, then as soon as you hit a small bump you'd just be
bonucing up and down almost constantly, which would be a
bit disconcerting and it would mean the wheel would be
eccentric a lot of the time. The shock absorbers just
absorb the energy of the spring, so that the spring
compresses on drops / bumps then extend back to original
length and stay there, without wobbling. (or suppressing
the 2nd order oscillatory term of the control equation,
just to sound posh)

The shock absorbers might waste some energy from pedalling
if they weren't quite set up right, so thatsome of the
springs where slightly compressed while riding. Mainly
they would absorb the forces from dropping which otherwise
you have to absorb through rolling out, collapsing your
body, etc.

Bendy cranks sound like a recipe for falling off lots,
although it might be fun to try.

The other thought that has occured for Rayden's idea is that
with it being a parrallelogram there's nothing stopping you
from having 2 or more of these, which might make the wheel
stronger / stiffer in the rotational direction.

John

P.S. The exam went fine, cheers. It was digital electronics,
it's just 's and 1's, right?

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napalm wrote:
> *Right, firstly Rayden the amount of time you put into all
> your wonderful diagrams is admirable, and the ideas behind
> them bloddy excellent. I was just thinking, if the uni
> would only be good for dropping etc as said before
> somewhere wouldnt it be easier to make suspension cranks-
> like semi bendy ones. I realise that a suspension seatpost
> would be nesecarry otherwise there goes fathers day. Well
> my ideas from the land of ignorance, Keep up the awesome
> work, Mark *

Bendy cranks... You can do the design on those. I don't see
any use for them.

johnhimsworth wrote:
> * The other thought that has occured for Rayden's idea is
> that with it being a parrallelogram there's nothing
> stopping you from having 2 or more of these, which might
> make the wheel stronger / stiffer in the rotational
> direction.*

Good point. I added a model of that. Looks really funky but
I don't see why it wouldn't work.

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Like I said I don't know anything about getting a patent.

I may be naive but if you can prove you had the idea first
no one else can patent it. So if you were to show us it
would still be your idea, unless someone else showed they
had thought of it before you.

I'm not sure I want to patent it. I prefer to think about
such things with other people. I certainly wouldn't want to
come up with a great idea and then have no one do anything
with it because I had the patent and I didn't do anything.

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I don't know if it's different from country to country, but
I think patent applications usually (or used to) require a
working model of the idea (assuming it's for something you
can build a model of).

Though one person might get the basic idea in their head,
another person might be the one to actually build it, then
do all the tweaks and rethinks necessary to get it to
finally work. Who deserves the credit then?

An example of this is the Unicycling Society of America.
Charlotte Fox Rogers (one of the charter members)
indicated to Bill Jenack in a letter in the late 60s that
this would be a good idea. Bill started the organization
in 1973. He gets the credit. Though somebody else may have
thought of the idea years before, she didn't do the work
to make it happen. Plus Bill may have thought of it 10
years before that.

Same applies to selling unicycles online. I thought that
would be the best way to get quality products to people with
actual useful information about unicycling. But I didn't do
it. When John Drummond contacted me in early 1999 about
doing it, I jumped all over the idea and offered to help.
But he did all the work, and deserves all the credit.

The parallelogram idea looks interesting, but I'm not sure
how those parallelograms are supposed to work. Do they
eliminate the problem of windup?

So far, suspending the axle within the wheel looks like a
fascinating engineering challenge, but I don't see us
getting to a solution that doesn't weigh as much as several
Coker wheels. To combine the shock-absorbing abilities with
the necessary lateral and drive-direction stiffness, it
seems like lots of materials will be required.

So, at risk of taking this already-long post in a different
direction, how about we use some kind of conventional
suspension on the wheel, and run the pedals off a drivetrain
that can compensate? In other words, keep the pedals on
either side of the wheel, but have the wheel suspended. This
would still probably be quite a bit heavier than a normal
wheel, but might be easier to figure out mentally without
building working models!

I thought of it first... :p

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John Foss, the Uni-Cyclone
"jfoss" at "unicycling.com"
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because they are easy, but because they are hard." -- John F. Kennedy,
1961
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Originally posted by johnfoss
> I thought of it first...

Hey John, I know that I'm just teasing all of you again by
not showing you my suspended muni design, but it's a little
bit because of what you said above. From last september,
I've spend countless hours working on a working prototype.
Now that it's all conceived and the production plans are
made, I don't want to screw all the work and let a japanese
cie get all the credit for the first fully suspended
unicycle. As for patent pending of the machine, I'm on it.
(don't worry Rayden and pete, it's not the same design as
yours):p Sorry but I guess you'll have to wait until late
summer to see it in action.

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vincelemay - Quebec unicyclist
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Wow. You spend time at work for a week and come back to a
thread and find it's 6 pages long!

johnfoss wrote:
> *I don't know if it's different from country to country,
> but I think patent applications usually (or used to)
> require a working model of the idea (assuming it's for
> something you can build a model of).*

It's a "used to" in the United States. And your protection
for "thinking of it first" expires one year after publishing
the idea. I believe posting in this forum counts as
publishing so if you want to patent you're idea you've got
less than 365 days to get an application into the proper
format and submitted. Legal expenses for doing this with an
original mechanical design generally run from $4,000.00 to
$9,000.00. Applying for patents in other countries add
roughly another $10,000.00, but are necessary if you are
concerned by infringements from foreign manufacturers.

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[EngineeringHat]

The discussion has proceeded far enough that some clear
design requirements can be stated:

1) The wheel/suspension system must be rotationally stiff;
i.e., torque applied to the hub must transfer directly to
the rim with minimal windup.

2) The wheel/suspension system must be radially soft; i.e.,
opposing forces applied at the rim and hub should
compress the wheel between those two points.

3) Some level of radial damping is desireable, level to be
determined through experimentation.

4) Radial springiness is desireable; again, level TBD
through experimentation.

5) The rim must track rigidly in a plane passing through the
hub at the central point and normal (at right angles) to
the hub rotational axis.

6) The wheel/suspension system should be as light as
possible; weight TBD through design.

The rest of the requirements concern the standar "-
illities"; reliablity, maintainability, marketablity,
and so forth:

7) The wheel/suspension system should be as durable as
possible; durability TBD through market resistance.

8) The wheel/suspension system should be as simple and
reparable as possible.

9) etc...

[/EngineeringHat]

If I can figure out how to post a powerpoint slide I'll
submit a design to the discussion.

Tim

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Here are a few of the key ideas:

1) The sub-rim/spokes/conventional rim structure is light,
stiff and allows a wheel to be built with any rim/tire
combination.

2) The shock/spring mechanisms are as tangential as possible
so that they resist rotational motions well and radial
motions poorly.

3) The pivots and shock/spring mechanisms would be designed
to resist lateral motions as much as possible to keep the
wheel rotating in a plane centered on and perpendicular
to the hub axis.

Thoughts?

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I already had an idea of doing what Cyberbellum did. Good
idea putting the spokes on the outside of the suspension.
But I still like my parallelogram design which would
eliminate windup, while his would only minimize it. Putting
them at a tanget to the hub is a good idea though, if that
design were to be used.

John, I will think about putting the wheel on a seperate
suspension from the pedals.

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Ooohhhh! That suspension wheel is becoming really great!:cool:

Those are all nice ideas, but you should also think in 3D
when you're designing. I do like your parallelogram-
stifening bars-, maybe it could be like a 4 bars structure
to avoid side-to-side twisting (brake rubbing). My 2 cents.
Keep on the good engeneering!

Vincent

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