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Thread: Another New Wheelchair Measurement Post

  1. #11
    Quote Originally Posted by Essie View Post
    Thanks Chas! Your drawing made me realize that the back seat angle is independent of the dump. IE 90 degrees back seat angle is always perpendicular to the floor, regardless of the dump.
    You're welcome. TiLite (and some others) measures backrest angles this way. Some other manufacturers measure the way you thought. No industry standard exists.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

  2. #12
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    @ chas
    height of chair seat: 17"
    fingertips to floor: 14" (just call me "monkey girl")
    Last edited by Essie; 09-03-2012 at 10:23 AM.

  3. #13
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    Another question for a PT/seating specialist but I really would like user experience and opinions:

    When I sit I have anterior pelvic tilt. When sitting upright I maintain my shoulders over my hips but I have exaggerated lumbar and thoracic extension. In other words, I sit with more than normal lumbar curve and a less than 90 degree hip flexion. I have the ability to sit with with less lumbar curve and my hips at 90 degrees (quite frankly, it relieves some of my lumbar pain to sit more normally) but I feel I loose lateral stability and I have to concentrate to do it for any length of time.

    So the question is should the PT/seating specialist contour the back seat angle to match my anterior pelvic tilt or should she aim for something closer to 90 degrees (in relation to the seat)? Please know I recognize this is a forum; I am strictly looking for user opinion on which is more comfortable not for medical advice. Thanks!

    E

  4. #14
    Quote Originally Posted by Essie View Post
    @ chas
    height of chair seat: 17"
    fingertips to floor: 14" (just call me "monkey girl")
    WARNING: I am really not qualified to determine your chair measurements. This is intended only to inform you of the possibility that your initial RSH of 15.5" may be high. Your seating tech should be able to determine the appropriate RSH much better. Fingertips touching the axle is just a rule of thumb; determining proper RSH for pushing efficiency is actually far more complex and more flexible. Attached at the end of this post is a relevant research paper.

    So, "mg" , your fingertips are about 3" below your bottom's bottom (ignoring dump effect). The axle height of 24" wheels is 12". So your RSH+cushion is 15". Subtracting your cushion thickness (1.5") leaves a tentative chair RSH of 13.5":
    Attachment 46385

    But very few, if any, chairs with 24" wheels can get that low of RSH. And, with a 16.5" FSH, that would leave you with 3" dump (I stand regularly, and have 3" dump for pushing efficiency).

    According to the TR order form, it's available with 13.5" RSH with 22" wheels.
    Attachment 46386
    Attached Images Attached Images
    Last edited by chasmengr; 09-03-2012 at 12:40 PM.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

  5. #15
    Quote Originally Posted by Essie View Post
    Another question for a PT/seating specialist but I really would like user experience and opinions:

    When I sit I have anterior pelvic tilt. When sitting upright I maintain my shoulders over my hips but I have exaggerated lumbar and thoracic extension. In other words, I sit with more than normal lumbar curve and a less than 90 degree hip flexion. I have the ability to sit with with less lumbar curve and my hips at 90 degrees (quite frankly, it relieves some of my lumbar pain to sit more normally) but I feel I loose lateral stability and I have to concentrate to do it for any length of time.

    So the question is should the PT/seating specialist contour the back seat angle to match my anterior pelvic tilt or should she aim for something closer to 90 degrees (in relation to the seat)? Please know I recognize this is a forum; I am strictly looking for user opinion on which is more comfortable not for medical advice. Thanks!

    E
    THIS is way beyond me, and may well influence your best RSH (among other things).
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

  6. #16
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    Quote Originally Posted by chasmengr View Post
    WARNING: I am really not qualified to determine your chair measurements. This is intended only to inform you of the possibility that your initial RSH of 15.5" may be high. Your seating tech should be able to determine the appropriate RSH much better. Fingertips touching the axle is just a rule of thumb; determining proper RSH for pushing efficiency is actually far more complex and more flexible. Attached at the end of this post is a relevant research paper.

    So, "mg" , your fingertips are about 3" below your bottom's bottom (ignoring dump effect). The axle height of 24" wheels is 12". So your RSH+cushion is 15". Subtracting your cushion thickness (1.5") leaves a tentative chair RSH of 13.5":
    Attachment 46385

    But very few, if any, chairs with 24" wheels can get that low of RSH. And, with a 16.5" FSH, that would leave you with 3" dump (I stand regularly, and have 3" dump for pushing efficiency).

    According to the TR order form, it's available with 13.5" RSH with 22" wheels.
    Attachment 46386
    THANK YOU AGAIN! I have short legs and a long torso. This is part of the reason I always ditch the seat cushion (otherwise, I cannot get to enough of the wheel). Do you find your back hurting with 3" dump?

    E
    Last edited by Essie; 09-03-2012 at 12:59 PM.

  7. #17
    Quote Originally Posted by Essie View Post
    Another question for a PT/seating specialist but I really would like user experience and opinions:

    When I sit I have anterior pelvic tilt. When sitting upright I maintain my shoulders over my hips but I have exaggerated lumbar and thoracic extension. In other words, I sit with more than normal lumbar curve and a less than 90 degree hip flexion. I have the ability to sit with with less lumbar curve and my hips at 90 degrees (quite frankly, it relieves some of my lumbar pain to sit more normally) but I feel I loose lateral stability and I have to concentrate to do it for any length of time.

    So the question is should the PT/seating specialist contour the back seat angle to match my anterior pelvic tilt or should she aim for something closer to 90 degrees (in relation to the seat)? Please know I recognize this is a forum; I am strictly looking for user opinion on which is more comfortable not for medical advice. Thanks!

    E
    Consider a solid backrest with some space under it for your butt to slide under a little, basically to mimic how you would sit in something like the photo below. It baffles me how so many seating "specialists" prescribe backs that extend straight down to the seat, which inherently will force butts forward & create a slump in posture.


  8. #18
    Senior Member elarson's Avatar
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    That was really nice of you to make a drawing Chas. I would like to do one of a chair we plan to order soon. Is it possible you could send me your drawing so I can use it as a starting point so I don't need to reinvent the wheel (sorry for the pun)? I'd really appreaciate it.

    Quote Originally Posted by chasmengr View Post
    I drew your chair up conceptually in Google Sketchup ....
    Partner of an incredible stroke survivor. Limitations: hemiparesis and neglect (functional paralysis and complete lack of awareness on one side). Equipment: TiLite ZRA 2 and 2GX, Spinergy ZX-1, RioMobility Firefly. Knowledge: relative newbie for high-level equipment (2012), but willing to try to help others who are new with similar limitations (definitely not a guru, but inquisitive).

  9. #19
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    Yes, Scott.... that is exactly how I sit in my "desk" chair. My current WC uses the simple tension adj back and I have never been able to get a comfortable fit. I transfer out of it into my desk chair whenever possible. Thank you for the advice.

  10. #20
    Quote Originally Posted by Essie View Post
    Do you find your back hurting with 3" dump?
    Well, I also use a home-made ergo seat, so dump has been modified some. I rolled for a year without the ergo, and my back never hurt (except when I lowered my backrest height for several weeks - remedied with help from this forum ). When I started using my ergo insert, I noticed no difference, but yet I am very hesitant to stop using it; it is very comfortable.

    I need to run some errands - be back later.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

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