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New chair advice for a noob. Considering a ZRA

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    #31
    Originally posted by faji_tama View Post
    That IS a pretty big change. If I'm looking at that right, there's still a bit of a dump in the chair right? My main concern would just be with stability/how likely I would be to endo or fly out of my chair if I hit bumps or do anything active - aside from that, I dont think it'd be particularly difficult, nope.

    For reference, I believe the original measurements for the ZRA in my first post were the same as what this Revolution was ordered with. There may have been adjustments made afterwards though (but it was so long ago that I've forgotten - I've had this chair for five or six years now)
    Looking at your pics, you`ve got a horrible seating posture, to much backrest angle, too low rear seat, too width seat, well if i tell you the true i don`t see nothing correct there.
    Your long arms will be better pushing 25" rear wheels, so forget 24" wheels.
    For your sci level go for 92º backrest, no more than 95º.
    If in your pic you`ve got 15" rsh, you will need to go at less to 16.5" for rear seat.
    If you want to keep 4" dump you will have to go for fsh 21.5" and that will make you footplate very high, because you`ve got short legs, but the important thing is seating ok, not the distance between your feet to floor.
    Anyway 4" is much dump for your level, with 3" you will have enough.
    Order footrest front reduction.
    Of course softroll casterts by froglegs.
    80º front angle is ok, specially if your frame depth is going to be 16"(not long) so you will keep a good distance between rear and front axles wheels and the chair will have more stability.

    Comment


      #32
      Using rear wheel diameter for reference to scale your pic and the CAD, this gives you some idea how you might fit in a 15x15+2 85 degree frame. TiLite originally provided me with the CAD drawing for my ISS presentation in March. An actual chair was never produced for it. I may have lost some proportionality because I altered the angles of your hips, knees, and ankles. You should also know that the seat-to-footrest that I drew is shorter than the CAD spec.
      Last edited by SCI_OTR; 29 Dec 2011, 11:21 AM. Reason: Changed spec for seat depth.

      Comment


        #33
        Originally posted by SCI_OTR View Post
        . . . this gives you some idea how you might fit in a 15x15+2 82 degree frame. . . .
        did you mean 85 degree frame like the CAD shows?

        (PS: Your ability to manipulate and annotate drawiings/pics is amazing and superbly helpful.)
        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>

        Comment


          #34
          Originally posted by chasmengr View Post
          did you mean 85 degree frame like the CAD shows?
          No. I mean 85 degrees like my edited version.

          The quote of me in your post appears to have a typo!

          Comment


            #35
            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>

            Comment


              #36
              Some sitting measurements, in case they help at all:
              • Top of knees to soles of feet (with shoes on): 20" (so 4" ROHO + 16" distance to footplate sounds about right)
              • Rear to front of knees: 22"
              • Hip to hip: 14"
              • Rear to shoulders: 20"
              • Shoulders to middle fingertip: 32"
              • Wrist to middle fingertip: 8"


              SCI, I'm trying to make sense of the CAD, and a few questions come up. That 4" on the bottom is for the casters right? I was thinking of 5x1.5s though, so how would that change things? And what about toto's suggestion regarding 25" vs 24" wheels?

              I did a bit of searching on the forums, and read that larger wheels are harder to start, but roll better/further. Parts of SF are fairly hilly, but I have pretty good upper body strength too, so I'm wondering if 25" might be better...

              Comment


                #37
                Originally posted by faji_tama View Post
                I was thinking of 5x1.5s though, so how would that change things? And what about toto's suggestion regarding 25" vs 24" wheels?
                but I have pretty good upper body strength too, so I'm wondering if 25" might be better...
                5 X 1.5 casters are better for outdoors, give a better ride to the chair, 4"x1.5 are ok too, but only if they are softroll by froglegs.
                I think tilite don`t offer them in their order form, so just order the wheelchair with std caster with the size you want and after buy this ones, if you are an outdoor man go for 5 by froglegs too, 4 are just a bit lighter and the chair became a bit more agile in quick turns 90º at home.

                About the 25" rear wheels, here are a lot of guys using them, just ask if one of them after have tried 25" went back again to 24" in the next chair, i don`t think so.

                I go better with the 25" even uphills.

                Comment


                  #38
                  Originally posted by faji_tama View Post
                  I was thinking of 5x1.5s though, so how would that change things?
                  During ordering process (pre-build), switching from 4" to 5" caster would not affect other measurement like FSH. After the chair is built, switching from 4" to 5" would raise the FSH 1/2". (And conversely, switching from 5 to 4 after build would lower the FSH a 1/2".)

                  But, if you talk to TiLite (or Frog Legs) before build, they might tell you if they have a fork model with which you can switch from 4 to 5 after build while mainlining FSH. To maintain FSH after build, the 4" caster must use a 1/2" lower axle hole than the 5".
                  Last edited by chasmengr; 30 Dec 2011, 11:31 AM.
                  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>

                  Comment


                    #39
                    <from post #1>
                    Originally posted by faji_tama View Post
                    I have a fairly strong core and very good upper body strength, and want a wheelchair that I can use as an everyday, but still be active in.
                    Originally posted by faji_tama View Post
                    And what about toto's suggestion regarding 25" vs 24" wheels?

                    I did a bit of searching on the forums, and read that larger wheels are harder to start, but roll better/further. Parts of SF are fairly hilly, but I have pretty good upper body strength too, so I'm wondering if 25" might be better...
                    I have never used 25" wheels. I chose 24" because I have bursitis in my shoulders, and I don't work out like I should. But if I had good, strong shoulders, I would definitely try them out. Just my $0.02.
                    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>

                    Comment


                      #40
                      Originally posted by faji_tama View Post
                      Some sitting measurements, in case they help at all:
                      • Top of knees to soles of feet (with shoes on): 20" (so 4" ROHO + 16" distance to footplate sounds about right)
                      • Rear to front of knees: 22"
                      • Hip to hip: 14"
                      • Rear to shoulders: 20"
                      • Shoulders to middle fingertip: 32"
                      • Wrist to middle fingertip: 8"


                      SCI, I'm trying to make sense of the CAD, and a few questions come up. That 4" on the bottom is for the casters right? I was thinking of 5x1.5s though, so how would that change things? And what about toto's suggestion regarding 25" vs 24" wheels?

                      I did a bit of searching on the forums, and read that larger wheels are harder to start, but roll better/further. Parts of SF are fairly hilly, but I have pretty good upper body strength too, so I'm wondering if 25" might be better...
                      Since I see the 1.5" in your caster selection, if you spec 5's they will build the chair for a 5" caster swivel radius. I personally prefer 4" casters (especially on such a relatively narrow and short frame). Provided you select the standard double sided bearing fork (in which case the casters will be mounted in the middle hole), you can always order 5's and use 4x1.5's in the lowest hole later on. On the other hand, if you initially went with 4x1.5"'s but had doubts, it may not be possible to upgrade to 5" casters due to lack of swivel space.

                      In your situation, I think you should have a pretty good idea about your frame length before determining the wheel diameter because are some things to consider beyond which wheel is easier to push.

                      I use 25x1 Spinergy's with Schwalbe Marathon Evolutions on my 17x16+0 85 degree ZRc S1. My STF heights are a little higher than yours and my COG is 3.5". On flat surfaces, I can get up to speed relatively quickly and maintain that speed with very little effort. Put me on a anything other than an ADA spec grade, however, and I have to lean forward in order to keep the front down--putting me at a biomechanical disadvantage. I have found that moving my feet onto the front half of the footrest can mitigate this a little by shifting the COM forward. If flat surfaces weren't my primary environment of use, however, I'd probably move my rear axle back.

                      If you encounter hills a significant portion of the time, a little more wheelbase will help keep the front end of the chair down when pushing uphill. (Perhaps 15"+2?). This is where the Schulte dimension mentioned earlier in this thread would allow you to compare your current chair with the proposed chair in the CAD drawing.

                      One side note, do not use the COG on your Revolution to determine the COG for the ZRA2. It my be only 1-2", but , the effective COG is actually much greater because you have such a reclined back angle. Fortunately this spec is easily adjustable on a ZRA2 and the range will be easily within your optimal setting.

                      More wheelbase will also provide better hand placement on the push rims and reduce the angle of the frame when in a wheelie/ascending curbs than is the case with a shorter frame.

                      Wheel lock clearance may also be tight because there may be little room between the location where the wheel lock needs to be and and the beginning of the front frame bend. I cut about 1/2" off the length of the handles of my Quickie Ego scissors to solve this problem on my chair.

                      A 25" wheel would also make it a little more difficult to clear the rear wheel during transfers.

                      Looking at the bigger picture, however, I would think your new chair is going be be much, much, easier to transfer into/out of.

                      BTW, I checked and the CAD was actually drawn for a 25x1 Spingery with treaded tire (a.k.a. Primo Passage). It may only be a little larger in diameter than your current 24's w/ grey everydays.

                      On completely flat surfaces, energy generated from the force of the push stroke imparts kinetic energy to the wheels and the chair moves forward once any rolling resistance is overcome. Although I have yet figure out the precise physics, it seems that applying forces to the push rims of larger diameter wheels on a grade are more likely to be countered by rotational force in the opposite direction that will cause the front end to lift instead of the entire frame rolling forward.

                      I'm interested to hear t8burst's and grommet's thoughts on the matter as they are familiar with the terrain in SF.

                      Or any engineer/physicists types who may wish to enlighten us on the effect on wheel diameter when going up a grade. Off topic, I know, but these are the types of things I ponder during my down time. (I wish I knew I'd find a practical use for physics when I was in college 25 years ago so I would have paid attention).
                      Last edited by SCI_OTR; 31 Dec 2011, 4:26 AM.

                      Comment


                        #41
                        Originally posted by SCI_OTR View Post

                        A 25" wheel would also make it a little more difficult to clear the rear wheel during transfers.
                        ).
                        Remember is a low para, i didn`t notice any difference in my transfers.

                        Comment


                          #42
                          Hey guys, sorry about going MIA - just got back Stateside a few days ago. So, to sum it all up, my new chair config is looking something like this:

                          Frame Finishes: Satin
                          Color Anodizing Package: Black
                          Rear Seat Width: 16"
                          SCI, I wasn't sure if you were suggesting a 15" or 16" width, because your CAD drawing said 16", but you typed 15" everywhere else...
                          Front Seat Width: No Taper
                          Seat Depth: 15" + 2"
                          Front Seat Height: 19.5"
                          Rear Seat Height: 16.5"
                          Front Angle: 85°
                          Seat to Footrest: 16"
                          If this distance is wrong, can it be adjusted at all?
                          Footrest Type: Titanium Footrest w/ Flat ABS Cover
                          Front End Type & Footrest Width: Standard Front End - 12" (1.5" Taper)
                          Seat Back Type: Folding Titanium Adjustable Height
                          TiShaft Back Release Bars: Titanium
                          Seat Back Height: No Push Handles - Short - 10"
                          Still wondering about this one - suggestions? I was originally thinking of keeping my current medium 15", but I don't lean on it as it is right now anyway.
                          Seat Back Options: 4" Deep Backrest Rigidizer Bar
                          Seat Back Angle: 92°
                          Based on toto's suggestion. I still don't understand how the relationship with the degree + SCI level though.
                          Center of Gravity: 3.25"
                          Rear Wheel Spacing: 0.75" with spacers
                          Camber: 4°
                          Camber Tube Type: Carbon Fiber Camber Tube
                          Front Casters: 5" x 1.5" Plastic Wheel w/ Poly Tire
                          Do I need to specify to Tilite to use the middle holes to mount these? So that I can switch to 4" casters later if I change my mind?
                          Front Forks: TiLite Standard Forks w/ Titanium Fork Stems
                          The above two to be replaced with Unitines and Soft Rolls. How difficult are these to install yourself? I'm... reasonably handy.
                          Rear Wheels: 25" Black Spinergy LX
                          Axles: Titanium Quick Release
                          Rear Wheel Tire: Primo (to be replaced by Schwalbe Marathon Evolutions)
                          Handrims: Aluminum - Long Tab
                          Wheel Locks: Surelocks
                          These are the ones that have a custom Tilite option right?
                          Upholstery Colors: Black
                          Back Upholstery: Tension Adjustable by Straps
                          Seat Upholstery: Tension Adjustable Bolt-On
                          Seat Cushion: ROHO High Profile Quadtro
                          Side Guards: Carbon Fiber Rigid Removable - Standard
                          Calf Strap: Bodypoint Padded Velcro Adjustable - Large


                          If I made any mistakes here, let me know! And I've appreciated all the help over the past few weeks!

                          Comment


                            #43
                            Originally posted by totoL1 View Post
                            5 X 1.5 casters are better for outdoors, give a better ride to the chair, 4"x1.5 are ok too, but only if they are softroll by froglegs.
                            I think tilite don`t offer them in their order form, so just order the wheelchair with std caster with the size you want and after buy this ones, if you are an outdoor man go for 5 by froglegs too, 4 are just a bit lighter and the chair became a bit more agile in quick turns 90º at home.

                            About the 25" rear wheels, here are a lot of guys using them, just ask if one of them after have tried 25" went back again to 24" in the next chair, i don`t think so.

                            I go better with the 25" even uphills.
                            I've got 2 chairs, one with 25" other 24", I can notice the difference easily and would go for a 25" wheel from now on every time. Both are fitted with Marathon Evo Plus tires just fyi.

                            Comment


                              #44
                              Originally posted by faji_tama View Post
                              Rear Seat Width: 16"
                              SCI, I wasn't sure if you were suggesting a 15" or 16" width, because your CAD drawing said 16", but you typed 15" everywhere else...
                              It's not really a CAD drawing made specifically for you. It is a drawing based on a CAD drawing for hypothetical specs I provided to TiLite. You would know best whether you would ft in a 15" wide chair or need to go out to 16".

                              Originally posted by faji_tama View Post
                              Seat to Footrest: 16"
                              If this distance is wrong, can it be adjusted at all?
                              You have more than enough adjustability here.
                              Originally posted by faji_tama View Post
                              Seat Back Height: No Push Handles - Short - 10"
                              Still wondering about this one - suggestions? I was originally thinking of keeping my current medium 15", but I don't lean on it as it is right now anyway.
                              Or you could go 12-16.5, pull out the extension tube and put a plug in the back post which would give you a single post set at 12". It saves a smidgen of weight and causes less wear on the backrest ears.
                              Originally posted by faji_tama View Post
                              Seat Back Options: 4" Deep Backrest Rigidizer Bar
                              Just curious. Why? It would push a backpack out away from the backrest.

                              Do you want the backrest that locks when folded? If so, don't forget to select it.

                              Originally posted by faji_tama View Post
                              Front Casters: 5" x 1.5" Plastic Wheel w/ Poly Tire
                              Do I need to specify to Tilite to use the middle holes to mount these? So that I can switch to 4" casters later if I change my mind?
                              Should happen automatically.
                              Originally posted by faji_tama View Post
                              Wheel Locks: Surelocks
                              These are the ones that have a custom Tilite option right?
                              Ask for engineering special "stephen212" when you place your order Surelocks.

                              Ask for a CAD drawing before placing your order.

                              Comment


                                #45
                                Originally posted by SCI_OTR View Post
                                Just curious. Why? It would push a backpack out away from the backrest.

                                Do you want the backrest that locks when folded? If so, don't forget to select it.
                                I'm assuming the rigidizer bar is the one behind the back seat that is sometimes used as a mounting point for push handles and the like right? Or is it something else? When I'm out traveling in places like Taiwan, and need to be lifted up curbs or carried up stairs, it's a handy anchor point from which others can lift me...

                                What are the pros/cons of a locking folded backrest? My Revolution doesn't lock when folded, and I haven't noticed too many issues with that.

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