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Thread: Spec'ing out a new chair!

  1. #1

    Question Spec'ing out a new chair!

    Hello All, long time lurker new to the forums. Was in motorcycle accident back in 2000 that left me T8-9 paraplegic. The reason I finally joined the forums is its time for a new chair. The amount of knowledge many on this forum have, can help me out a great deal. Im working with a dme but the more insight the better. Ive been in an Invacare A4 Titanium for the past 6 years, I have no complaints about the chair, but its time for something new. Ive spent countless hours reading posts and I think between the forums help, the dme, and me I should be able to nail down specs for a TiLite ZR.

    This is what Ive got so far, measurments are off of current A4

    RSW 15
    SD 17
    FSH 19.5
    RSH 16.5
    Front Frame Angle (need help here)
    Titanium Open Loop Foot Rest 17.5
    Footrest Width 9 (3.5" taper)
    Seat Back Folding Titanium, Adjustable Height, Locks when Folded, CF TiShaft release bar
    Seat Back Height 8.5-11 set at 10
    4" Rigidizer Bar
    Seat Back Angle (need help here)
    COG 2.5
    Rear Wheel Spacing .75
    Carbon Fiber Camber Tube 4* (with Additional Spacers)
    4x1 Billet Aluminum 5 Spoke Caster with Soft Roll Tire
    Frog Legs
    25" Spinergy LX Wheels
    Stainless Quick Release Axles
    Marathon Plus Evos
    Natural Fit Lt Standard Grip Handrims Long Tabs
    Composite Scissor Lock
    Tension Adjustable Seat Upholstery (will be getting JetStream / ADI Back)
    Solid Seat Upholstery
    Roho Low Profile Cushion
    Carbon Fiber Fold Down Rigid Side Guards (small)

    So questions are:

    1) I can fit the width of a finger between my hips and side guards now. Didnt used to be this tight, I quit smoking end of last year and put on a few lbs. (Maybe 10) Should I go to 16" wide?

    2) When I originally got this chair it didnt have a solid back, Should I make it 1" longer to account for that? Sitting upright I can still get 2 fingers between back of knee and seat pan.

    3) They automatically add 1" when using frog legs, should I add another to make it like my A4 or just leave it at +1?

    4) I currently have an angle adjustable footplate. It is tilted down in the back. I was thinking of going with the open loop design just cause I like the way it looks. Are your feet more likely to slide off the footplate without the angle?

    I think thats it for now. I posted a few pictures so you can see what I look like in my current chair. Also maybe you can tell me front frame angle and rear seat angle. Im open to any / all comments or suggestions. Thank you all in advance and if more detailed pics are needed let me know.

    Mike
    Attachment 44309

    Attachment 44310

    Attachment 44311

    Attachment 44312

    Attachment 44313

  2. #2
    Welcome...and excellent photo's, very helpful.

    Your front appears to be an 80 degree front, via the tool I used on one of your pictures.

    If you still have room between your hips/legs and the side guards, you don't want to go wider...rather if you were pushing on the side guards, then consider.

    The adding of the +1 can be tricky. When I ordered my TR I assumed there would be +1" because of my frog legs, but they did not add the +1" for my chair, so I had to stipulate it. You will have to be sure your DME stresses to Tilite that you want +1 added to your chair, whether that be natural because of the Frog Legs or added. If Tilite were to add +1 and then you stipulate +1, you'd end up with +2" and I don't think that is what you want.

    You appear to me, for what that is worth, to sit quite well, I am not sure about the need for another inch of seat depth because of a solid back.
    C5-6 Complete - 8/13/1982

  3. #3
    Senior Member wheeliecoach's Avatar
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    I agree with Brianm that you may not need another inch of seat depth for the solid back. If you are thinking of going with the 4" rigidizer bar, that should help with the solid back. I also think you do look good sitting in your current chair.

    Welcome to the forums fellow Connecticut resident (or would you prefer Nutmegger ). You will get excellent advice on this site.
    "Unless someone like you cares a whole awful lot nothing's going to get better. It's not." - Dr. Seuss

  4. #4
    9" footrest width is too tight imo.

  5. #5
    All A4's have an 80 degree front frame angle. Are you going to stay with the same angle or go a little sharper? Your 17" seat depth looks OK with an 80 degree frame but would be too deep for 85 degrees.

    If you are looking to get a chair with a fixed rear STF height, why not go with a TR or the soon to be available TR3? I raise this prospect for a couple of reasons...

    a) FrogLegs suspension forks will behave completely differently on a ZR than they do on your A4 because the ZR's cantilevered (open) frame flexes slightly at the bend due to the lack of a lower frame rail. Many CC members go with the standard fork or UniTine fork and get 4 or 5 x 1.5 FrogLegs aluminum hub soft rolls off chair. That combination provides good impact absorption yet preserves stability during transfers, weighs less, and will probably result in fewer problems down the road..But I digress.

    b) A 2.5" COG seems conservative on a ZR for someone with your level of injury with a 17" seat depth and 80 degree frame angle. I'm concerned 2.5" could turn out to be outside the what you may eventually determine your optimal setting should be on a different model of chair. The ZR's COG adjustability is more limited than it is on a TR. I spec'd my 85 degree 17x16+0 ZRc at 3.0" and found it to be too front heavy. I currently run about 3.5". It is hard to translate between models and everyone is different, but I think most users would find a ZR with those specs to be front heavy.

    c) A 15" wide ZR will have less usable width between the front frame tubes than your A4 because it uses a larger tubing diameter (1.25" -vs- 1" OD). As a result, you will lose about 1/2" of space (1/4" on each side). It's hard to tell if it would pose a problem, but your A4 looks like a snug fit already.
    The lack of a footplate or cover on top of the titanium tubular footrest will also position the sides of your feet in closer proximity to the bend where the extension tubes transition into the footrest. It's difficult to explain, but if you read this post from a few years back, you will see what I am talking about.

    Are you currently able to position your feet all the way back on the footplate if you have to? Are you considering purchasing a FreeWheel? Just some things to consider.

    Since the TR also uses 1" tubing, at least you know what you will be getting. *With the ZR, you may want to consider 1.5" of taper if you feel you will be comfortable staying with a 15" seat width.

    Lastly, keep in mind that the rigid fold down carbon fiber sideguards and ADI back need to be able to clear one another. You'll definitely want to let them know the ADI back is in your future and request a CAD prior to ordering. I ran into an issue with the rigid fold down side guards on this chair.
    Last edited by SCI_OTR; 04-01-2012 at 02:28 AM.


  6. #6
    Now you have me second guessing my decision of going without FrogLeg forks on my next TR SCI_OTR.
    C5-6 Complete - 8/13/1982

  7. #7

    For Comparison's Sake: An 18x16+1 85 Degree ZR2

    Full post in the CareCure CAD Repository. Same STF heights, wheel and caster sizes as your proposed specs, but with an 85 degree frame angle. Note the 3.25" COG...




  8. #8
    Thank You all so much for the insight and the welcomes!

    Wheeliecoach, I noticed many of your posts befored I signed up. Im actually just a few towns over in west haven. I work in east haven.

    Sci_Otr, I will be happy to entertain your idea of going to a box frame. You are much more knowledgeable than I when it comes to this and Im grateful you took / take the time to help so many.

    So any idea on estimated time when they say "soon to be released tr3" ? 2 months, 6 months, 10 months?

    The reason I was going with a cantilever design was because of the aesthetics. But you raise multiple good points. I do like the thinner tubing of the box frame, my A4 has treated me extremely well over the past 6-7 years, overall I will probably be more comfortable in what I am used to.

    I currently have a demo zra, and I tried a Q7. Both of them are hard to tell how they actually ride because while I can sit in them and roll around they are quite aways from my actual needed measurements.

    Moving forward, I can move my feet all the way back if I remove / adjust my leg strap. My footplate is quite angled so if I move them all the way back the back of my shoe almost touches the ground. I can make it more flat but I think my feet are more likely to fall off the front. Also I think it would raise my knees higher causing me not to clear the kitchen table. What if I raise my front stf height 1"? I can then lower the footplate a little more, keeping my knees down? Every adjustment you make effects all the others, thats what drive me nuts, all the variables

    What is the advantage of the 85* frame? I would probably shorten seat depth 1" because as u stated with my feet that far back the back of my knee is pretty much touching the seat upholstery.

    That last pic there (along with others you posted) is actually why I was looking at the zr2. It just looks cool.

  9. #9
    FSH 19.5
    RSH 16.5

    How tall are you? How did you arrive at these seat heights? The FSH may be just too high to make fitting under many desks and tables kind of tight. I'm in the 5'8" neighborhood and have spec'd the seat height of most of my chairs at 19" --> 16".

    Front Frame Angle (need help here)
    My current ZR has an 85 degree angle, +1 frame.

    Titanium Open Loop Foot Rest 17.5

    Footrest Width 9 (3.5" taper)
    As noted by TotoL1, 9" width (as TiLite specs it) is very narrow.

    Seat Back Folding Titanium, Adjustable Height, Locks when Folded, CF TiShaft release bar
    Seat Back Height 8.5-11 set at 10
    4" Rigidizer Bar

    I'm partial to fixed back chairs, but if you're going to be ordering a JetStream-style back, what's the point in having an adjustable height back rest? Note how low I was able to cut the back post tubes on my ZR -- nothing for me to bang my elbows into .


    Seat Back Angle (need help here)
    COG 2.5

    That ain't much. My COG is 4" and feels quite stable.


    Rear Wheel Spacing .75
    Carbon Fiber Camber Tube 4* (with Additional Spacers)
    4x1 Billet Aluminum 5 Spoke Caster with Soft Roll Tire
    Frog Legs

    I ordered Frogleg Unitines and casters separately (from Sportaid -- they were running a promotional) and swapped out the OEM standard TiLite forks/casters.

    25" Spinergy LX Wheels
    Stainless Quick Release Axles
    Marathon Plus Evos
    Natural Fit Lt Standard Grip Handrims Long Tabs
    Composite Scissor Lock
    Tension Adjustable Seat Upholstery (will be getting JetStream / ADI Back)
    Solid Seat Upholstery

    My carbon fiber seat pan attaches to the frame with Velcro. I ordered my ZR with instructions not to drill holes into the frame. I've adapted this same approach to my other chairs without any issues. Being able to remove the pan in seconds is a great convenience.

    Roho Low Profile Cushion
    Carbon Fiber Fold Down Rigid Side Guards (small)

  10. #10
    Nice chair stephen!

    Quote Originally Posted by stephen212 View Post

    How tall are you? How did you arrive at these seat heights? The FSH may be just too high to make fitting under many desks and tables kind of tight. I'm in the 5'8" neighborhood and have spec'd the seat height of most of my chairs at 19" --> 16".


    Im about 5'10". Not sure how arrived there, but after wheels were changed 24"-25", frog legs were added, solid back was added, thats were it ended up.

    As noted by TotoL1, 9" width (as TiLite specs it) is very narrow.

    I am going to take TotoL1 and others advice and add an inch or so to the footrest. I honestly never saw it as a problem but now that it was pointed out, I see it is a little tight. I thought it was supposed to be to keep feet in position.


    I'm partial to fixed back chairs, but if you're going to be ordering a JetStream-style back, what's the point in having an adjustable height back rest? Note how low I was able to cut the back post tubes on my ZR -- nothing for me to bang my elbows into .


    Mine now is sorta like yours is, I removed the adjustable tubes and secured the back to the lower tubes. I dont care about the adjustable height, but I do like the option of adjustable angle. I dont know exactly where mine is currently.


    That ain't much. My COG is 4" and feels quite stable.


    As SCI_OTR pointed out I cant compare my current cog to a ZR. I will probably opt for about 3.5"

    I ordered Frogleg Unitines and casters separately (from Sportaid -- they were running a promotional) and swapped out the OEM standard TiLite forks/casters.

    How is the chair with the froglegs? Does it feel stable? Have you been thrown out of it when hitting a bump or irregularity in the road?

    My carbon fiber seat pan attaches to the frame with Velcro. I ordered my ZR with instructions not to drill holes into the frame. I've adapted this same approach to my other chairs without any issues. Being able to remove the pan in seconds is a great convenience.

    That pan is really cool but pricey. Actually the whole chair is cool. Thanks for the input.

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