Suspension MUni

Discussion in 'rec.sport.unicycling archive' started by Pete66, Jul 5, 2004.

  1. Pete66

    Pete66 Guest

    Checkout my cool full suspension MUni, hands up who
    wants one?

    cheers Pete

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  2. Tennisgh22

    Tennisgh22 Guest

    sweet lord that is an awesome muni.

    **raises hand**

    -grant

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  3. Pete66

    Pete66 Guest

    Heh, cheers mate... unfortunately this model wouldn't quite
    work. I think it needs hinges between the hub & the rockshox
    or/and (as you say) flexible rim but it's just an idea.
    Here's a closeup.

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  4. Pete66

    Pete66 Guest

    .. PS Please don't sue me Kris, I know its got ur sig on it
    but um, yeah.

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  5. Joe

    Joe Guest

    Thats really cool Pete!

    When I clicked on the thread I thought it was going to be
    another person asking if you can get suspension unicycle...
    but I was pleasently suprised with your pic! :D

    Joe,

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  6. Xtremeskier_

    Xtremeskier_ Guest

  7. Wow! Nice!

    The problem is that the spoke force is tensional, not
    compressional. So mabey if the piston shafts were flexible
    and had a pulling shock absorbtion, it'd work. The biggest
    problem is the rim's not strong enough to handle most muni
    riding. It'd taco on the first hop.

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  8. Gizmoduck

    Gizmoduck Guest

  9. Cyberbellum

    Cyberbellum Guest

    GizmoDuck wrote:
    > *Any engineers out there able to comment? *

    Agreed, Pete that's an awesome graphic. VERY nice work!!

    From an engineering sense there would need to be hinges at
    the hub end of the pistons. Assuming the rim was strong
    enough to hold together as a semi-rigid hoop (heavy, but
    possible), then think of what happens when you squish the
    wheel down. The bottom spoke compresses, which is fine, but
    the upper two spokes aren't pointed in the right direction
    so they can't. If the upper two shocks can't pivot at the
    hub then the pistons will jamb sideways in the cylinders.

    Ok, so let's imagine that the hub ends of the rockshocks are
    pivoted. Now it has beautiful suspension action. Sure, the
    rim has to deform a bit, but there's a lot of room for
    deformation so it could be done without any catastrophic
    failures. What happens when you pedal?

    If the hub ends of the rockshocks are hinged freely then the
    hub can spin a bit within the wheel. If it's really free
    then the hub could rotate 30-40 degrees in either direction
    without sending any torque to the rim. This would be really
    bad. The unicycle would not be ridable. So purely free
    action is out too.

    There might be a way to compromise. Perhaps use hard rubber
    bumpers on either side of the hub hinges so that the spokes
    don't rotate around the hub very freely.

    As Edison said, invention is 1% inspiration and 99%
    perspiration. Most people don't ever get to the 1% bit.
    Pete, you're well past that part. Keep at it and you'll get
    to a ridable machine. Once you do can I take it for a ride?

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  10. Daino149

    Daino149 Guest

    Would more shocks help the strength issue? How about welding
    "spokes" that go across the diameter of the wheel without
    hitting the hub? I don't know to much about the physics of
    this, but it looks like a real cool idea.

    Daniel

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  11. Nickjb

    Nickjb Guest

    I like the idea, very novel. I designed a couple of
    unicycles to isolate the wheel from the cranks a year or two
    ago. They only ever made as far as the back of an envelope,
    not on to CAD and certainly not into prototyping. It all
    started to get a bit complicated.

    Anyone remeber the Tioga (IIRC) disc wheel that was laced up
    with kevlar string (again IIRC) to give a form of
    suspension? This design reminds a bit of that. Might go and
    look it up.

    Nick

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  12. Vincelemay

    Vincelemay Guest

    Hey Pete, good idea!

    It's cool to see that I'm not the only one who want to push
    the limits of the MUni designs.

    I'm a student in mechanical engeneering, and I had a
    conception project about a fully suspended unicycle.

    The design I came up with (after more than 10 other models),
    is way more complicated than yours. But one of the rejected
    design was similar: instead of the RockShocks, it had curved
    metal plates (like a trailer suspension) disposed as spokes.

    We will soon be producing a prototype out of the final
    design. Since nothing is machined yet, I don't want to show
    the complete 3D model. But you will certainly hear of it
    when it's done and after we had tested it severely.

    Here's an overview about what we started with:

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  13. Vincelemay

    Vincelemay Guest

    (Sorry for the crappy link, this is what I meant)

    SUSPENDED UNICYCLE PROJECT

    INTRODUCTION : The project was designed to improve the
    mountain unicycles used in very technical and rough
    terrains. For the first prototype, we are going produce it
    from basic steel. If the feeling of the design is good and
    we want to continue with the idea, we are going to make
    another prototype correcting the possible mistakes made on
    the first one and make it from chromo and aluminium.

    PRINCIPAL OBJECTIVES : The proposed solution should be
    adapted for downhill utilisation. The suspension system
    should help to gain control and stability, which is
    necessary for that type of practice, and by the way reduce
    fatigue a little. The solution should be light enough and
    resist to the conditions met in unicycle downhill.

    ESSENTIALS CONDITIONS :

    The proposed solution should: ·have a suspension system,
    adjustable from 3 to 7 inches ·permit the use of some
    standard parts: -26’’ wheel with a 3’’ wide tire -6’’ disc
    brake conformed to the SI standard -27.2mm seat post -
    Profile crank arms -Standard bicycle shock ·resist to the
    abuse of a 190 pounds load from a 12 feet drop ·resist to
    impacts inherent from the practice ·not weight more than 25
    pounds for the total assembly ·reduce the effects of
    pedaling on the shock ·permit to the distance between the
    saddle and the cranks axle to not be affected by the
    suspension ·permit the alignment between the saddle, the
    axle and the wheel to be the most constant possible trough
    the suspension path ·permit the propulsion to work like a
    standard unicycle, without play between forward and backward
    ·permit saddle height adjustment from 21 to 27.5 inches
    (from the axle to the top of the saddle) ·not cost more than
    2000 CAN$ in material ·have to lowest profile possible

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  14. Rayden

    Rayden Guest

    I would be very interested to see how you guys figured out
    how to do this. Not only because it would be fun to ride
    one, but I like mechanical things. :) You have any idea as
    to when you will show your designs?

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  15. Tom Holub

    Tom Holub Guest

    In article
    <[email protected]>,
    johnfoss <[email protected]>
    wrote: ) )The obvious challenge is to make something that
    will allow the wheel to )deflect, or deform, without
    weighing a ton, and while not interfering )with the
    transmission of drive force to both turn and stop the wheel.

    What about in the hub? You could start with a design like
    Blue Shift's hub, and instead of having gears in between
    the central axle and the secondary (spoke flange) axle,
    you could have small piston-type shock absorbers. If you
    ran them fairly tight, they wouldn't affect handling too
    much. -Tom
     
  16. Klaas Bil

    Klaas Bil Guest

    On Tue, 18 May 2004 19:38:00 -0500, "aust" wrote:

    >would it not be hard to hop?!

    Maybe, because of the weight. But the springiness of the
    wheel would be beneficial to hopping.

    Klaas Bil - Newsgroup Addict
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  17. Nick_pf

    Nick_pf Guest

  18. Johnfoss

    Johnfoss Guest

    That was a great graphic. Too bad the concept doesn't work,
    because if the suspension can be in the wheel, the rider has
    a chance of having his feet, not just his butt, isolated
    from the bumps of the trail. That should be the goal of a
    suspension system for MUni.

    The obvious challenge is to make something that will allow
    the wheel to deflect, or deform, without weighing a ton, and
    while not interfering with the transmission of drive force
    to both turn and stop the wheel.

    Sorry, I don't have any bright ideas at the moment...

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