Announcement

Collapse
No announcement yet.

Specs for a ZRA2 with flip-up footrests (DU 100082)

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #31
    Originally posted by elarson View Post
    I hate to be a pest, but I really need to respond about our CAD/specs tomorrow. Can anyone give their input about whether lowering the front seat height to 18.5" and rear seat height to 17" and increasing the frame length to 19.5" or more would help with our problem of a forward tippy chair?
    I think switching to standard flip up footplates would suffice. Lowering your front STF will require the seat-to-footrest to be shortened.

    You should also weigh what you know about how your husband uses his chair versus TiLite's concerns about forward tippiness. If he has one foot on the floor most of the time, the front tippiness would be less of an issue. If he is bearing significant weight on one or more of the footplates, it could be a concern.

    Given your previously expressed concerns about replacement parts and my personal experience working with people with dense hemiplegia and hemi-spatial neglect, I really think the disadvantages of FrogLegs forks far outweigh any advantages. They are the single greatest contributor to the forward tippiness of a chair with an 85 degree frame angle and require more room to swivel.

    TiLite's 6" soft roll has good impact absorption and probably has a swivel area similar to a 5" caster with FrogLegs forks. Selecting them would mean going with an 80 degree frame angle, however.

    Comment


      #32
      Originally posted by elarson View Post
      I hate to be a pest, but I really need to respond about our CAD/specs tomorrow. Can anyone give their input about whether lowering the front seat height to 18.5" and rear seat height to 17" and increasing the frame length to 19.5" or more would help with our problem of a forward tippy chair?
      FSH was 19, now 18.5. RSH was 17.5, now 17. Difference was 1.5 and is still 1.5 which is a minimal difference IMHO. Frame length was 19, now 19.5, that does increase the wheelbase a little which is what I think Tilite meant when they said they make shorter chairs than the competition.

      I wonder if you could switch to a box frame and avoid some or all of these issues such as interference with the brake and cross member and self propel.
      I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

      Comment


        #33
        Can you respond by putting the burden on TiLite--

        i.e. Dear TiLite: 1) Just what is the minimum required distance between the front of the upholstery and center of the caster to achieve stability and 2) With all of your CAD capability and experience, what change would best accomplish that--1" shorter seat depth, longer frame, 80 degree frame angle, some combo?

        You'd then have more info to judge the effect on self propulsion and comfort. Otherwise, you have to guess until something meets their unspecified stability distance criterion.

        For what it's worth, I'm 6' tall with the same leg lengths as your husband and have a 17" deep seat and find it comfortable. If you have to go shorter on the depth, it might work.
        I don't have an SCI--I have generalized weakness (PPMS) with POTS and gait problems.

        Comment


          #34
          I would think shorter seat depth would make the problem worse, since the issue is essentially frame depth being too short for the specs?
          Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

          I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

          Comment


            #35
            It has nothing to do with the frame length. It has everything to do with the combination of footplate, FrogLegs suspension forks, minimal dump, and 85 degree frame angle. Unless the user consistently reverse swivels the casters, FrogLegs suspension forks compress which causes the front of the chair to dip. If the footplates locate the user's feet in front of the front frame, they will exert more leverage.

            TiLite didn't say they wouldn't build the chair, but they are making sure that the user is aware of their concerns. If this chair was not intended to be foot propelled and the user bends forward with both feet on the footplates it is going to tip. It goes back to the questions I posed in my previous post. It may not be a problem for her husband if he has a foot on the ground and doesn't lean forward and bear weight on the footplates, but TiLite has no way of knowing that.

            Comment


              #36
              Sorry, I miss spoke. I over simplified while I was just thinking literally about the issue being a distance one according to tilite. Quoted from earlier tilite said the problem reffered to their "minimum required measurement for the distance between the front of the seat upholstery to the middle of the caster in the trailing position" and the chair not meeting this minimum distance. So shortening the seat depth could either be done with or without changing the actual frame length. If its shortening the upholstery alone and not the frame length, whats the point as the issue isn't about the actual length of upholstery but how that corresponds with the person once sitting in the chair. If the seat depth is shortened while shortening the frame depth, thats decreasing the distance from upholstery to the center of the caster.

              I should have clarified, not just assumed that what was in my head was obvious. And "for the specs" I meant the usage of frog legs etc, in general all of the specific options chosen. For example if the frog legs and footplate was different, it wouldn't be an issue. If the frame length was longer between the seat and the frog legs and footplate, it wouldn't be an issue. But the combination of the length specs and the options (frog legs forks, foot plates chosen) is the cause.
              Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

              I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

              Comment


                #37
                Originally posted by ~Lin View Post

                ...If the frame length was longer between the seat and the frog legs and footplate, it wouldn't be an issue. But the combination of the length specs and the options (frog legs forks, foot plates chosen) is the cause.
                That is what I was trying to say, effectively creating a longer wheelbase, but SCI seems to be saying it can't be made longer enough, or I misunderstood.

                I was dumped on my face once from a chair and rebuilt that chair with another to make another much better one with a longer wheelbase. Another time, another chair, this time with Froglegs and apparently too much of a bump I nearly got tossed out of the chair. Instead I removed the Froglegs that day and opted for big wheels on ordinary casters.
                I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

                Comment


                  #38
                  Thanks everyone for your input, and especially your elaboration and drawing SCI_OCT. I superimposed it on the previous CAD with the longer frame length and indeed there was no difference.

                  About how my husband will use it, he will have one or both feet on the floor most of the time while propelling and doesn't lean forward and bear weight on the footplates. He will use the footplates when being pushed and when resting (usually only one), or while using a power add-on (both). I think it would be difficult for him to consistently reverse swivels the casters.
                  Originally posted by SCI_OTR View Post
                  It has nothing to do with the frame length. It has everything to do with the combination of footplate, FrogLegs suspension forks, minimal dump, and 85 degree frame angle.
                  About the Footplate, as far as I can see, if the Depth Adjustable Flip-Up was placed as far back as possible, which is also his preferred foot position, it would be the same as the Standard Flip-Up -- or am I missing something? It would not be a big issue to change to the Standard Flip-Up if not. Here are the pictures so you can see what I am talking about.

                  Standard Aluminum Flip-Up:

                  Aluminium Depth Adjustable Flip-Up:

                  I'm not sure I am understanding how 6" soft roll would be any more stable if it means 80 degree frame angle with his feet (weight) more out front. Would switching to a 90° frame angle and 4" casters help?
                  TiLite's 6" soft roll has good impact absorption and probably has a swivel area similar to a 5" caster with FrogLegs forks. Selecting them would mean going with an 80 degree frame angle, however.
                  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).

                  Comment


                    #39
                    I was referring to using the 6" soft roll without the FrogLegs suspension fork to get similar impact absorption without the "dip factor". FrogLegs forks compress quite a bit and set off a chain reaction of sorts. Advantages of the standard flip up are less weight in front of the caster and they are more likely to stay up. Of course, the composite will stay up even better.


                    Comment


                      #40
                      I had not thought of the overall weight of the footplate making a difference. I was looking at it more from the position forward/backward. Interesting about composite staying up better. We definitely want them to stay up, or he will have a tough time propelling if he is being wacked by the footplates. Switching to either standard aluminium or composite would be no problem if it helps with the tippiness. He has the composites now, and although they are a bit flimsy, it looks like they are more streamlined too.

                      I'm still really reluctant about giving up on Frog Legs for 6" casters. Sometimes his weak foot gets caught up in the casters and he does not realise it. It happened the least with the 4" casters, is okay with the 5", but anything bigger is bad (he has big feet -- size 13 US / 46 Europe).

                      Living in Europe, we have almost no places that are not bumpy. Those bumps really hit him hard, and he has almost been flipped out forward a few times by a 1 cm bump when other people are pushing him. I think he can compensate better for a dip rather than a jolt. Also, with the ZX1 power add-on I think it would really help so he does not get jolted on bumps, and I would think that he should not have any problem with forward tippiness because the drive unit will be compensating for it in the rear.

                      I know when you order the Frog Legs directly from them, they ask for the users weight. Is there a way to adjust the compression once you have them, like you can with RockShox rear shocks?

                      Originally posted by SCI_OTR View Post
                      I was referring to using the 6" soft roll without the FrogLegs suspension fork to get similar impact absorption without the "dip factor". FrogLegs forks compress quite a bit and set off a chain reaction of sorts. Advantages of the standard flip up are less weight in front of the caster and they are more likely to stay up. Of course, the composite will stay up even better.
                      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).

                      Comment


                        #41
                        Frog legs suspension uses elastomers, its not an adjustable shock. To change it up you'd have to swap out for different elastomers. They're color coded for the differences.
                        Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

                        I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

                        Comment


                          #42
                          If you make some changes like the footrest would it be possible to sign off on the CAD with the five inch frog legs, then if its too tippy swap them out with the six inch soft rolls with the TiLite forks? How would this effect the dump, toe in and such if something like that was done? Or is that even possible? I just thought it might give you more options and give you the ability to get a feel for how tippy it is with his feet on the ground, and his style of pushing.
                          Last edited by Melissa And Ruby; 1 Jan 2013, 8:44 PM.

                          Comment


                            #43
                            I would take a 6" caster and an 80 degree frame. A chair being pushed by someone else is especially front heavy, and FrogLegs suspension forks could actually make the chair more prone to throw the user. Ironically, the additional flex and weight of a folding frame chair may make it better suited for that particular scenario.

                            Comment


                              #44
                              Thanks ~Lin. I had not looked into that at all, even though I thought I had read most of the Frog Legs posts.

                              I can't seem to find any information on the Frog Legs site about the elastomers. I did find this ZRA Exploded View on the Frog Legs site. Is the elastomer what they now call the "polymer"? See Installation of new polymer dampener.


                              I found it odd that when I got a quote from Sportaid we needed to specify the user weight, but not when we were quoted from a dealer through TiLite.

                              The Polymers look to be pretty cheap on the Frog Legs site if the Polymers are the same as the elastomers. Because we need this all quoted together for the government, I would prefer to buy extra's for a lighter person, should we need it, and also for maintenance.

                              Originally posted by ~Lin View Post
                              Frog legs suspension uses elastomers, its not an adjustable shock. To change it up you'd have to swap out for different elastomers. They're color coded for the differences.
                              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).

                              Comment


                                #45
                                We are hoping that with a ZX1 he would not need to be pushed very often. Our current thinking is 40% manual propulsion in our home, 50% ZX1 power add-on propulsion outside with bumps, 10% some else is pushing. In computer software, I would build for the 90% rather than the 10%. Would you still have the same view?
                                Originally posted by SCI_OTR View Post
                                I would take a 6" caster and an 80 degree frame. A chair being pushed by someone else is especially front heavy, and FrogLegs suspension forks could actually make the chair more prone to throw the user. Ironically, the additional flex and weight of a folding frame chair may make it better suited for that particular scenario.
                                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).

                                Comment

                                Working...
                                X