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Thread: Need opinions on the ZRA

  1. #1

    Need opinions on the ZRA

    I'm in the process of buying a ZRA from sportaid.

    Here are the dimensions that I think I want to go with:

    - 85 Degree Front Angle
    - 16"W x 18"D
    - STF Heights: 18"F/15.5"R
    - Center of Gravity: 3.75"
    - Footrest Width: 14" VFrame
    - 5x1.5 Casters
    - 1" Wheel Spacing
    - 6 Deg Camber
    - 92° back angle

    What am I missing here? I know it's adjustable. I just want to get it as close as possible to correct the first time.

    It's hard to visualize between the chair I'm in primarily because my current front end is 70°-not adjustable.

    I can do a wheelie but I'm concerned that at 85°, a 3.75 cog will feel much different.

    I am aiming for tippy because the problems of not enough dump in a heavy front end converged in a drunken pedestrian accident on a railroad track this past winter. Broke my leg on the face plant. All healed up in a little smarter… I think. :-)

    Can anybody do cad with the above numbers?

    I appreciate your insight and comments.

  2. #2
    Senior Member tooley's Avatar
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    if you're sure about your RSH why not order a ZR? The COG is still adjustable. I honestly don't think the 15 degrees in front end will make alot of difference, unless you've got two lead feet. Even then, a 1-hole adjustment of COG should be enough.

    What do you guys think?

  3. #3
    Quote Originally Posted by radio_buddha View Post
    I'm in the process of buying a ZRA from sportaid.

    Here are the dimensions that I think I want to go with:

    - 85 Degree Front Angle
    - 16"W x 18"D
    - STF Heights: 18"F/15.5"R
    - Center of Gravity: 3.75"
    - Footrest Width: 14" VFrame
    - 5x1.5 Casters
    - 1" Wheel Spacing
    - 6 Deg Camber
    - 92° back angle

    What am I missing here? I know it's adjustable. I just want to get it as close as possible to correct the first time.

    It's hard to visualize between the chair I'm in primarily because my current front end is 70°-not adjustable.

    I can do a wheelie but I'm concerned that at 85°, a 3.75 cog will feel much different.

    I am aiming for tippy because the problems of not enough dump in a heavy front end converged in a drunken pedestrian accident on a railroad track this past winter. Broke my leg on the face plant. All healed up in a little smarter… I think. :-)

    Can anybody do cad with the above numbers?

    I appreciate your insight and comments.
    That chair IMO is not well configurate.

    You want a 18 seat depth, that is because you are a tall guy, but you order 15.5" RSH, to little for a tall guy.

    6º camber is too much for a daily chair, never more than 4º, but i will go for 2º for a daily chair.

    A front reduction in V to 14" is too wide, there is not going to be any reduction.
    If you are going to order a 16" seat wide i think you will have to go for a front reduction between 10.5" to 11.5", 11" probably will be ok.

  4. #4
    @tooley Even if the ZR has small COG adjustability, the front caster forks do not have any angle adjustability. Any change in the default COG would mean that the caster fork is not perpendicular to the floor, right? To me, the ZR comes when the settings become absolute.

    @toto yep. I'm 6'1". It was the January face plant and leg break that spooked me to think about being lower in the rear with a 2.5 dump.

    The original setting was 18f/17r, 4°, 25559 wheels. Since 2006, it is now 17.5f/16r, 6°, 24540. It feels a bit small. It has already proven to be dangerous.

    My body measurements are 19 from rear to back of knee. 17.5 from back of knee to heel.

    As for the footrest width, my 2006 drawing says 10 so I would probably go with 11.5. I think I came up with 14 because I have an ABS footplate I made that is 12 inches wide. Something doesn't make sense there. I need to make a phone call about that.

    Like the picture you posted in another thread, I will be going with an extra inch on the frame.

    Anyway, gentlemen, my cup is empty. This thread is to help me fill gaps in my knowledge before I go to the wolves who will gladly sell me the wrong chair as easily as they will sell me the right chair.

  5. #5
    What's your level of injury. The higher the level the more dump is helpful. If you are getting a ZRA, they are completley adjustable. The main thing to get right is the width and length of the seat. everything else can be changed.

    On the ZR, COG can be changed in that the camber bar is bolted onto a bracket that is level; making cog adjustments is easy without interference of the front caster angle.

  6. #6
    Thank you for your thoughts on the ZR. If that is the case, I could have less nonsense to adjust. I'm really close to my settings. This isn't drastic like I'm riding on 22 inch wheels.

    Injury level… It's a severe peripheral neuropathy which looks like quad below the knees and elbows. I have a very strong trunk and sense of balance and I do a lot of transfers so I've always rolled with a 1 inch dump. My last spill made me think that I should have a 2 inch dump. I don't want to go beyond two. I don't think it's needed.

  7. #7
    Quote Originally Posted by radio_buddha View Post

    @toto yep. I'm 6'1". It was the January face plant and leg break that spooked me to think about being lower in the rear with a 2.5 dump.

    My body measurements are 19 from rear to back of knee. 17.5 from back of knee to heel.

    As for the footrest width, my 2006 drawing says 10 so I would probably go with 11.5. I think I came up with 14 because I have an ABS footplate I made that is 12 inches wide. Something doesn't make sense there. I need to make a phone call about that.

    Like the picture you posted in another thread, I will be going with an extra inch on the frame.
    .
    Another extra inch on the frame? more seat depth?, it`s going to be to long. If your body measurements are 19 from rear from back to knee you will be ok in a 18 seat depth same as frame depth.

    17.5 from back knee to heel you have to substract the profile of your cushion and you will have the mesasurement from the seat to the footplate.

    I assure you if you order a V front reduction with 14" footrest width, there is no reduction, because if your seat width is 16" and ZR diameter tube is 1.25" that mean that the inside tube width is 16-(1.25 x 2)= 13.5".
    The footplate don`t need to have the same wide as your feet, they can be a bit narrow, the really important is from bend to bend.
    This is a 11" V front reduction.

  8. #8
    Quote Originally Posted by radio_buddha View Post

    As for the footrest width, my 2006 drawing says 10 so I would probably go with 11.5. I think I came up with 14 because I have an ABS footplate I made that is 12 inches wide.
    .

    I don`t know how you would like to have your feet in your footrest but i like to have them like the pic on the top,for keep my feet and legs always in the correct position.

    The down pic is a front reduction too, but is a bit big and you can see that the feet could slide a bit from side to side.That footrest would be better with .5" less, even an ich less.
    Last edited by totoL1; 06-10-2010 at 06:24 AM.

  9. #9
    So 17.5 with a 2 inch seat cushion… 15.5 seat to footplate? 19.5 STF. Seems like I would not be able to reach things at that height. I'd definitely need to lose the keyboard drawer. It should not interfere with anything else.

    I'm going to get a measurement of the top of my knee to the heel. That will give me a better idea of what I need on the height.

    Regarding the foot plate width… I like to keep a couple inches between my ankles because I still use my legs to dress. I'll tip back on the anti-tips and prop my body on the back post to this brilliantly dangerous position where my shoulders, hips and knees are in the same a horizontal plane. :-)

    I will get a picture of my front end up within a couple days. The 14 inches might be slight but it was more than enough to improve my parking in those round restaurant tables with single legs.

  10. #10
    Senior Member chriZ's Avatar
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    I got a ZR and I'm 6'2".
    take a look of my measures and some pics here: http://sci.rutgers.edu/forum/showthread.php?t=116228

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