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Calculating your CoG

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  • Calculating your CoG

    In retrospect I thought it was a good idea to keep the CoG the same as the last wheelchair. Old wheelchair = 550mm from footplate to backrest. New wheelchair = 600mm from footplate to backrest. CoG is 100mm on both. Old wheelchair move like an SU27. New wheelchair moves like a Mack truck.

    I am gonna try moving the CoG 25mm increments untill I found the sweet spot.
    Everybody wants freedom.... They just don't want it for everybody else...

    A college professor, a man I now consider my dad, once told me...
    "The minute you let someone decide what you can and cannot do, your life is no longer yours." A truer word has never been spoken in my opinion.


    Professor Bill Johnston
    (1930- )

  • #2
    I have mine set to where my hand is directly over the hub and 1/2 way up the button. If COG is too Mack truck like I'll move it forward til it's a sportscar. With you being a T/10 incomplete, your back should be low and COG set forward.

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    • #3
      transfering plays a role too, clearing that wheel as we age gets trickier and more important but at t10 likely not an issue.
      other factors are backrest depth and angle as well. did you switch backs??
      Bike-on.com rep
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      c4/5 inc funtioning c6. 28 yrs post.
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      • #4
        Originally posted by Patrick Madsen View Post
        I have mine set to where my hand is directly over the hub and 1/2 way up the button. If COG is too Mack truck like I'll move it forward til it's a sportscar. With you being a T/10 incomplete, your back should be low and COG set forward.
        I found the sweet spot @ 140mm seem scarily too forward but it works. Might go further forward in more experiments

        Originally posted by fuentejps View Post
        transfering plays a role too, clearing that wheel as we age gets trickier and more important but at t10 likely not an issue.
        other factors are backrest depth and angle as well. did you switch backs??
        Funnily enough the the old chair which had 550mm length had a 80 degree front angle. New chair with 600mm length has 90 degree front angle so the frame comes out considerable more. I must say I do like it alot. Gives me just enought to rest on if I need to mid transfer.

        I did switch backs. Went back to a sling upholstery. If I can find one I like I may upgrade the upholstery to a carbon backrest.
        Last edited by Mutley; 12-02-2018, 07:57 PM.
        Everybody wants freedom.... They just don't want it for everybody else...

        A college professor, a man I now consider my dad, once told me...
        "The minute you let someone decide what you can and cannot do, your life is no longer yours." A truer word has never been spoken in my opinion.


        Professor Bill Johnston
        (1930- )

        Comment


        • #5
          You'll develop shoulder problems with your COG too far backward and back too high. The backward COG will make you reach too far behind you each push. That can add up to thousands of pushes per day that you are over-stressing your shoulders. The tall back will impede your torso from moving backward, which makes your shoulders do all the work, which stresses your shoulders even more. It's a double whammy. You want the COG as far forward as practically possible and the back as low as practically possible.

          25mm is a large move, you may want to try smaller increments. I moved my COG 12.7mm forward (3" to 3.5") and it made a big difference. Moving the COG 25mm forward would have made my wheelchair too backward tippy.
          Last edited by August West; 12-03-2018, 12:31 AM.

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          • #6
            Originally posted by Mutley View Post
            I found the sweet spot @ 140mm seem scarily too forward but it works. Might go further forward in more experiments
            I did switch backs. Went back to a sling upholstery. If I can find one I like I may upgrade the upholstery to a carbon backrest.
            Careful about being so far forward you're hitting your butt transferring. I did that with my and ended up with a shearing wound from hitting the wheel while transferring.

            I tried hard backs for thirty years, have a closet full of like new hard backs, and always went back to a sling until I found the Ride Back. I like the adjustments it provides without compromising the other adjustments.

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            • #7
              Originally posted by Patrick Madsen View Post
              Careful about being so far forward you're hitting your butt transferring. I did that with my and ended up with a shearing wound from hitting the wheel while transferring.

              I tried hard backs for thirty years, have a closet full of like new hard backs, and always went back to a sling until I found the Ride Back. I like the adjustments it provides without compromising the other adjustments.
              Nah the seat is a lot longer than the old whelchair thanks to an extra 100mm i needed to get the front to 90 degrees. If I'm gonna be hitting anything it'll be the seat frame.
              Everybody wants freedom.... They just don't want it for everybody else...

              A college professor, a man I now consider my dad, once told me...
              "The minute you let someone decide what you can and cannot do, your life is no longer yours." A truer word has never been spoken in my opinion.


              Professor Bill Johnston
              (1930- )

              Comment

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