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Thread: Rear seat height and front seat height

  1. #1
    Senior Member sowseng's Avatar
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    Rear seat height and front seat height

    I am helping friends to choose a wheelchair, would like to know how to choose a suitable rear seat and front seat height for him. What measurement should I take to decide the height of both?

    Any guideline for this ?

    Thanks.
    Life is meaningles, though you create the purpose.

  2. #2
    lots of factors at play here that you don't mention... height, leg length, injury level, occupational needs, etc.

    solution: get an adjustable chair.

  3. #3
    Here is the website http://www.sci-info-pages.com/wheelchair_man.html





    Manual Wheelchair Setup & Measurement Guide



    Seat Depth
    1 Measure from the most posterior point of the body to the inside of the knee, minus at least two inches. Some prefer more leg overhang to make room for their hand when lifting their leg.
    Back Height
    2 Measured from the seat base to the top of the chair back. Depends on how much upper back support is needed, and also affects freedom for the upper body to rotate.
    Rear Seat to Floor
    3 Measurement from the ground to the rear seat edge. Relative to the front seat-to-floor dimension, this determines the rearward slope ("dump" or "squeeze") of the seat.
    Hanger Angle
    4 Determines how far the toes extend away from the body, measured from the horizontal. A tighter angle allows the chair to turn around in less space. Depends in part on ability of the knee to bend towards the perpendicular.
    Seat Width
    5 Determined by the widest point of the body from knee to hip, plus an inch to ensure room to move. Consider bulk of clothing, particularly a heavy winter coat, if relevant.
    Wheel Camber
    6 Angle of the wheel relative to the vertical. More camber improves stability and agility, but also limits ability to pass through narrow spaces. A typical daily chair uses three degrees of camber.
    Front Seat to Floor
    7 Measure the leg from the back of the knee to the sole of the foot. Then subtract the thickness of the cushion when it is compressed. Next, add a minimum of two inches for footrest clearance. Do not add the footrest clearance if the chair will be foot-propelled
    coolbreeze c6/7

    Keep on moving don't stop!

  4. #4
    Quote Originally Posted by sowseng View Post
    I am helping friends to choose a wheelchair, would like to know how to choose a suitable rear seat and front seat height for him. What measurement should I take to decide the height of both?

    Any guideline for this ?

    Thanks.

    If the user don`t have their own preference, a good rsh will be that one when the user is sit and could touch with his fingers the rear axles, the front height determine the dump, and depends the insurence level and user preferences.

    red measurement is rsh and green is fsh.

  5. #5
    Senior Member sowseng's Avatar
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    Quote Originally Posted by coolbreeze View Post
    Seat Width
    5 Determined by the widest point of the body from knee to hip, plus an inch to ensure room to move. Consider bulk of clothing, particularly a heavy winter coat, if relevant.
    So, if the width is 15", I shall add 1" to it right?
    Life is meaningles, though you create the purpose.

  6. #6
    Senior Member rdf's Avatar
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    You have to measure your friend a this widest spot from his hips to his knee. Then you can add as many inches as he might need, or want. If he's 15" wide at the widest, a 16" seat width gives him half an inch on each side. Some people might want an inch, or more - depends on how close he want the wheels to be.
    Quote Originally Posted by sowseng View Post
    So, if the width is 15", I shall add 1" to it right?
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    Thanks!

  7. #7
    Senior Member sowseng's Avatar
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    Quote Originally Posted by totoL1 View Post
    If the user don`t have their own preference, a good rsh will be that one when the user is sit and could touch with his fingers the rear axles, the front height determine the dump, and depends the insurence level and user preferences.

    red measurement is rsh and green is fsh.
    Thanks, how about for those who have short body and long arms?
    Life is meaningles, though you create the purpose.

  8. #8
    for rsh and fsh determination, here's what I did:

    a) decide on chair and cushion thickness wanted
    b) decide diameter of rear wheel
    c) decide on front angle and type of footrest desired
    d) determine length of lower leg with typical footwear & determine length of footrest
    e) knowing front angle and footrest length, determine desired ground clearance beneath footrest (trigonometry helps)
    f) demo desired chair. with measurements and math calculations, set rsh for good propulsion (middle finger tips touch axle), set fsh for acceptable ground clearance (beneath footrest frame) and knee clearance (below table/desk/etc.)

    g) then get an adjustable chair so all settings can be fine tuned.

    if you want accuracy, be very aware that different manufacturers measure differently. Some measure rsh from rear of seat tubing, others measure from intersection of seat & back frames. Some measure front angle from the ground plane, others measure it from the seat frame. Etc. Thus, even when you tune your chair in, if you change manufacturers for your next chair, the tuned-in measurements may be 'wrong' for the next chair. Industry standardization would sure be nice, but it doesn't exist.

    ps. I forgot to mention seatpan selection. rigid versus sling seatpan can make a huge difference (1"+)
    Last edited by chasmengr; 03-22-2011 at 12:15 AM. Reason: typos and add ps
    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>

  9. #9
    Quote Originally Posted by sowseng View Post
    Thanks, how about for those who have short body and long arms?
    good propulsion efficiency remains the goal. during my selecting, I found a research paper that concluded the elbow angle should be between 90-110 degrees when seated properly with the hand resting on the top center of the handrim. that angle equates roughly to the tip of the middle finger touching the axle for most people.
    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>

  10. #10
    regarding seat width, user preference and side guards play a huge part. I can stand, so my seat width with side guards is wider (although less than 1") than my dressed hips so the chair stays on the ground when I stand. the side guards allow my chair to be relatively narrow for clearance through door frames. without side guards my clothes would always be touching my wheels.

    I've read here that some users prefer a narrower chair that grabs their hips so they feel more in their chair and less on it. I also have feeling, so pressure sores are not an issue for me.
    Last edited by chasmengr; 03-22-2011 at 12:18 AM. Reason: add sentence about sores.
    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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