Suspension MUni

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

  1. Rayden

    Rayden Guest

    Another screenshots showing what it would look like in
    compression.

    +-------------------------------------------------------
    ---------+
    | Attachment filename: prototype1compressed.jpg |
    |Download attachment:
    http://www.unicyclist.com/attachment/210975| +-------------------------------------------------------
    ---------+

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     


  2. Rayden

    Rayden Guest

  3. what orientation would the pedals be? If they were parallel
    to the rigid shock then surely nothing would move in the way
    it was meant to, and something would end up breaking?

    --
    theamazingmolio - A Unicylist, a juggler, and a prat

    Luke Duller ([email protected])
    Never trust anything you read on the internet
    ------------------------------------------------------------------------
    theamazingmolio's Profile: http://www.unicyclist.com/profile/5931
    View this thread: http://www.unicyclist.com/thread/32510
     
  4. I shouldn't think it;d break if the pedals were parallel
    to the not-really-a-shock. Looks like a pretty cool idea,
    my only thoughts being if one set of telesocping metal
    tubes will be strong enough to transmit all of the
    rotational forces.

    The other problem with all thse is that adding 3 shocks to a
    wheel will be very expensive, and will weigh a lot.

    Nice ideas though.

    John

    --
    johnhimsworth - Nullus Anxietas

    What if the hokey cokey really is what it's all about?
    ------------------------------------------------------------------------
    johnhimsworth's Profile: http://www.unicyclist.com/profile/1788
    View this thread: http://www.unicyclist.com/thread/32510
     
  5. This calls for a diagram...

    Say you were hopping, if the cranks were parallel to the
    shock, then the shock would be horizontal. All the wight
    of the rider (the pretty green arrow) would be
    transmitted along the shock, and the rim would all hinge
    around the other end (the pretty red bit). Common sense
    and physics tells us that, just for the purposes of
    hopping, the whole thing would work better were it hinged
    at the hub end. Unfortunately bitter experience tells us
    that with the forces involved, the chances are that
    something will bend or snap.

    Most of us have had problems with cranks bending, there are
    two of them to spread the load over, and they're only about
    half the length that this shock would be, meaning there's
    much less leverage involved. [image: http://www.unicyclist.-
    com/forums/attachment.php?s=&postid=211032]

    +-------------------------------------------------------
    ---------+
    | Attachment filename: prettypicture.bmp |
    |Download attachment:
    http://www.unicyclist.com/attachment/211032| +-------------------------------------------------------
    ---------+

    --
    theamazingmolio - A Unicylist, a juggler, and a prat

    Luke Duller ([email protected])
    Never trust anything you read on the internet
    ------------------------------------------------------------------------
    theamazingmolio's Profile: http://www.unicyclist.com/profile/5931
    View this thread: http://www.unicyclist.com/thread/32510
     
  6. The extra bit isn't a shock, the idea of that (I think,
    apologies if wrong) is that because the hinge is at the rim
    end the hub is no longer free to rotate within the wheel,
    avoiding wind up. The 3 shocks will still take the majority
    of the weight of the rider and the force from hopping. The
    telescopic bit would transmit rotatioanl forces from
    acceleration.

    In the situation you describe, when you press down on the
    pedals the telscopic not-a-shock would extend slightly and
    tilt down at the rim end, so that the hub will move
    downwards in a vertical line. It'd tilt backwards a bit as
    well, but probably not by too much. The load would be taken
    by the shock absorbers either extending or compressing.

    John

    P.S. this is a great distraction from revision. Pity the
    exams in just over an hour. Ah well.

    --
    johnhimsworth - Nullus Anxietas

    What if the hokey cokey really is what it's all about?
    ------------------------------------------------------------------------
    johnhimsworth's Profile: http://www.unicyclist.com/profile/1788
    View this thread: http://www.unicyclist.com/thread/32510
     
  7. Rayden

    Rayden Guest

    Yes John, that is what I am saying. ALL your weight would
    be on the three shocks. ALL the rotational force would be
    on the telescoping pole (its not really a shock so I'm
    going to stop calling it one). When you go off a jump the
    telescoping pole would bend at the rim and extend, or
    compress. There would be no pressure on it. ALTHOUGH if you
    go off a jump and the tire wants to rotate, then you would
    get pressure on it.

    Other notes. There is no reason not to use more shocks
    except expense. And the hinges might not like sideways
    forces. Perhaps attach them the same way as spokes, at an
    angle. This would require more shocks though. Or perhaps
    extra geometry that does not support the suspension, but
    prevents the rim from buckling sideways.

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  8. The point I'm trying to make, although I'm not very
    articulate in saying it, is that, because the telescopic
    pole is fixed rigidly to the hub, and hinged at the rim, if
    the pole were horizontal to the ground, then (hopefully) the
    pole would not be able to bend upwards at the hub, and it
    would not be able to extend or compress, because the force
    would be on a different plane, and so the wheel would be
    forced to hinge around the end of the pole.

    If you're hopping with the pole horizontal, then your
    weight, acting downwards on the hub, is effectively
    rotational force on the pole, and we know from bitter
    experience that the forces involved in trials, muni, and
    hopping, are enough to bend and break even the best
    equipment.

    One of your screenshots seems to illustrate the situation
    I'm trying to describe, In the pictue it shows the pole
    bending downwards but it doesn't take into account the fact
    that, when you're hopping, you're standing on the pedals,
    and keeping them horizontal.

    Basically, it's a very good idea, and I'm sure it could
    work, but your drawings don't seem to take into account any
    of the torque that would be transmitted through the metal
    pole, and because in the drawings the hub can rotate freely,
    the pole behaves as it would if it hinged at both ends.

    Would it be possible in the software you're using to make it
    so that the hub can't rotate?

    How easy would it be to model the wheel actually in use? i.e
    torque on the hub, weight visibly acting downwards, ground
    visibly acting upwards.

    It is of course perfectly possible that you've address all
    these issues, and I just can't see it, in which case I
    apologise for wasting your time.

    personally I think you desgin a fully enclosed unicycle,
    because I have to ride down to the supermarket now and its
    just started pouring with rain.

    --
    theamazingmolio - A Unicylist, a juggler, and a prat

    Luke Duller ([email protected])
    Never trust anything you read on the internet
    ------------------------------------------------------------------------
    theamazingmolio's Profile: http://www.unicyclist.com/profile/5931
    View this thread: http://www.unicyclist.com/thread/32510
     
  9. Tellurider

    Tellurider Guest

    A problem I see with all of this that hasn't been addresed
    is if you have ridden a suspension bike, when you get on
    your weight compresses the suspension. And with the
    suspension wheel the hub would be out of the center of the
    wheel or the springs would have to be tuned exactly to your
    weight to make the hub in the center of the wheel or I
    think it would cause a lot of extra resistance. And I think
    it would be great for drops, but unless the suspension was
    springs only it would be awful for trying to hop, as bike
    suspensions are dampend and it would absorb most of your
    hopping energy. and if it wasn't dampend the suspension
    wouldn't work very well on the trail. And another thing it
    wouldn't work with rim brakes but I guess a disk brake
    would work.

    --
    Tellurider - Dan Wilson
    ------------------------------------------------------------------------
    Tellurider's Profile: http://www.unicyclist.com/profile/4972
    View this thread: http://www.unicyclist.com/thread/32510
     
  10. Rayden

    Rayden Guest

    That is an excellent point and not one I considered. If the
    telescoping pole was a parallelogram then it could move up
    and down but maintain its horizontal orientation. This would
    make that part much more complex though. I'll see about
    changing my model.

    If you are asking about an animation, I can't do that
    with this software. If you are asking about rigging it up
    and then adding forces to see what happens, that I also
    cannot do.

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  11. Rayden

    Rayden Guest

    Here is what i mean. It would work like an A-arm. The
    parallelogram is hinged at all 4 corners. And would of
    course still telescope, i just didn't model that.

    +-------------------------------------------------------
    ---------+
    | Attachment filename: prototype1parallelogram.jpg
    | |
    |Download attachment:
    http://www.unicyclist.com/attachment/211095| +-------------------------------------------------------
    ---------+

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  12. Johnfoss

    Johnfoss Guest

    It keeps getting more interesting. Rayden's design is really
    different, and it's hard for me to picture the forces
    involved. I can see that each addition of more moveable
    joints and other parts is going to up the weight, but let's
    not worry about that and stick with the theory of making the
    design work.

    The main problem with Rayden's design, and I'm surprised
    nobody has mentioned it, is the non-suspended spot in the
    wheel. Each time you hit the non-suspended part (with the
    rigid arm at the bottom), you won't have any suspension. If
    your suspension is compressing from rider weight, you'll
    have a big hop in the wheel as you go over this spot. I
    guess there would be some amount of hop at the opposite side
    from there as well. So it would be like riding on a non-
    round wheel.

    You could keep the suspension pretty stiff, like what I have
    on my Wilder's seat post, but then you won't get as much
    benefit from the suspension action. This is probably fine
    for cruising on bumpy stuff.

    Using shocks would be more for riding and dropping, and less
    for hopping. For dropping, it's important that the rigid arm
    not be perpindicular to the pedals!

    Unfortunately I think the non-round issue would be the big
    problem, before one would get too worried about the
    strength of the rigid arm. That weakness could be covered
    by building it to larger specs. For cranks and axles we've
    been working with existing bike parts. For the wheel we can
    start from scratch.

    --
    johnfoss - Walkin' on the edge

    John Foss, the Uni-Cyclone
    "jfoss" at "unicycling.com"
    www.unicycling.com

    "We choose to go to the Moon in this decade and do the other things, not
    because they are easy, but because they are hard." -- John F. Kennedy,
    1961
    ------------------------------------------------------------------------
    johnfoss's Profile: http://www.unicyclist.com/profile/832
    View this thread: http://www.unicyclist.com/thread/32510
     
  13. Rayden

    Rayden Guest

    John, the rigid piece telescopes. It can get longer and
    shorter. It would do this any time the wheel is compressed,
    whether this piece be vertical or horizontal.

    As far as letting one of the 3 shocks act as the rigid
    piece, I think it might affect the strength of the shocks
    depending on orientation. Although I'm not certain of this
    and it might work. But you would get the problem I think i
    fixed with the parallelogram design. And adding a
    parallelogram to a shock would be much more difficult.

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  14. Johnfoss

    Johnfoss Guest

    Aah. Much better!

    --
    johnfoss - Walkin' on the edge

    John Foss, the Uni-Cyclone
    "jfoss" at "unicycling.com"
    www.unicycling.com

    "We choose to go to the Moon in this decade and do the other things, not
    because they are easy, but because they are hard." -- John F. Kennedy,
    1961
    ------------------------------------------------------------------------
    johnfoss's Profile: http://www.unicyclist.com/profile/832
    View this thread: http://www.unicyclist.com/thread/32510
     
  15. Rayden

    Rayden Guest

    The key is the parallelogram. There is no need the rest has
    to be shocks. They could be strong, stiff rubber bands done
    like this.

    +-------------------------------------------------------
    ---------+
    | Attachment filename: prototype1rubberband.jpg |
    |Download attachment:
    http://www.unicyclist.com/attachment/211125| +-------------------------------------------------------
    ---------+

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  16. Rayden

    Rayden Guest

    Close up of what I think the parallelogram would look like.
    This one has a shock in the middle of it. Each vertical
    cylinder is a hinge. I'm not so sure a shock in the middle
    of the parallelogram would be good though. It would have to
    be tuned differently due to its alternate length.

    +-------------------------------------------------------
    ---------+
    | Attachment filename: telescopewithshock.jpg |
    |Download attachment:
    http://www.unicyclist.com/attachment/211130| +-------------------------------------------------------
    ---------+

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  17. Thinuniking

    Thinuniking Guest

    UR UNICYCLE SUCKS!! Actually i just want to be able to do
    stuff like that on my p.c great idea would be really funny
    to see! Ben

    --
    thinuniking - we met a tree hugger(he rode a bike

    MUNI MILITIA now in the uk!
    ------------------------------------------------------------------------
    thinuniking's Profile: http://www.unicyclist.com/profile/4294
    View this thread: http://www.unicyclist.com/thread/32510
     
  18. Rayden

    Rayden Guest

    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 think there needs to be some sort of shock absorber or we
    would be bouncing all the time. But what if we used a bunch
    of springs (springs could be physical metal coils or rubber
    bands. anything springy) but then add 3 small dampeners.
    This might be lighter than 3 heavy duty shock absorbers.

    --
    Rayden
    ------------------------------------------------------------------------
    Rayden's Profile: http://www.unicyclist.com/profile/264
    View this thread: http://www.unicyclist.com/thread/32510
     
  19. I've been assuming something like on bike rear suspension,
    which is a spring (either air or coil) and a shock absorber
    in one unit. It's possible that something could be designed
    for a uni-specific shock/spring, but I don't know how it
    would differ from a bike shock, or if the extra cost from
    low production numbers could justify the improved
    performance.

    John

    --
    johnhimsworth - Nullus Anxietas

    What if the hokey cokey really is what it's all about?
    ------------------------------------------------------------------------
    johnhimsworth's Profile: http://www.unicyclist.com/profile/1788
    View this thread: http://www.unicyclist.com/thread/32510
     
Loading...
Loading...