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How much does a cantilever frame affect pushing efficiency?

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    How much does a cantilever frame affect pushing efficiency?

    Hi,

    How much does a cantilever frame affect pushing efficiency, if anyone can give a good idea of it in words?

    #2
    From what I've read, pushing efficiency is slightly reduced compared to a box frame of the same frame material and build quality. To my knowledge, no one has ever been able to measure a difference.

    From reading CCC posts by users who have used both TiLite's TR and ZR, the majority prefer the TR. My impression is the TR's frame holds its shape better (floating casters seem to occur more frequently on the ZR, ZRA, and AereoZ).

    Many other factors exist that affect pushing efficiency, such as fully welded versus adjustable, titanium (flexible) versus aluminum (stiff), slightly adjustable versus heavily adjustable, rigid versus folding. Remember, build quality is significant; Icon owners claim the build quality produces high efficiency in this highly adjustable cantilever-type chair. I used a Quickie 2 folder (box frame) which had horrible pushing efficiency compared to my TiLite AeroZ (cantilever).

    So the answer is, it depends.
    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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      #3
      I wouldn't worry about frame type very much. The way a chair fits and the components used for the wheels will make a bigger impact.

      Comment


        #4
        Originally posted by chasmengr View Post
        From what I've read, pushing efficiency is slightly reduced compared to a box frame of the same frame material and build quality. To my knowledge, no one has ever been able to measure a difference.

        From reading CCC posts by users who have used both TiLite's TR and ZR, the majority prefer the TR. My impression is the TR's frame holds its shape better (floating casters seem to occur more frequently on the ZR, ZRA, and AereoZ).

        Many other factors exist that affect pushing efficiency, such as fully welded versus adjustable, titanium (flexible) versus aluminum (stiff), slightly adjustable versus heavily adjustable, rigid versus folding. Remember, build quality is significant; Icon owners claim the build quality produces high efficiency in this highly adjustable cantilever-type chair. I used a Quickie 2 folder (box frame) which had horrible pushing efficiency compared to my TiLite AeroZ (cantilever).

        So the answer is, it depends.
        Floating casters can occur on any high end titanium frame. It is a function of how the frame is aligned when the footrest (or possibly the camber tube) is re-tightened. If the extension tubes aren't inserted evenly, the footrest creates torsion which can have an effect on the rest of the frame.

        While there are "technically" cantilevered qualities to it, the Icon is actually a modular frame.

        The terms "box frame" and "cantilevered frame" (aka "open frame", "L frame" or "mono tube frame") are normally used to describe only rigid frame models.

        In absolutely identical configurations a TR3 will be slightly more efficient than a ZR2. A Terminator Titanium will be more efficient than a Crossfire Titanium. No other comparisons are really possible, and , like rob1's previous questions, the magnitude of any differences would be negligible.

        I guess my question to rob1 is why are you asking these specific types of questions? I'm having a hard time telling if you are posing more-abstract questions intended to provoke deep theoretical discussion or if you are simply trying to choose your next wheelchair.

        Which frame type, model, and configuration would be best suited for your needs has to do more with your level of function, physical dimensions, and other individual factors.
        Last edited by SCI_OTR; 20 Oct 2012, 7:02 PM.

        Comment


          #5
          Originally posted by SCI_OTR View Post
          In absolutely identical configurations a TR3 will be slightly more efficient than a ZR2. A Terminator Titanium will be more efficient than a Crossfire Titanium. No other comparisons are really possible, and , like rob1's previous questions, the magnitude of any differences would be negligible.
          I'm presently using a fixed-back ZR2, which I am very happy with -- it's a great chair! I don't have any experience with the TR3 and wouldn't be able to offer a meaningful comparison between it and my ZR2 unless I had one that was identically configured. While it stands to reason that the TR3 would be more efficient, I remain, however, skeptical that the difference is anything other than subtle. Maybe if I were bigger and heavier the advantage in performance of a box frame chair might be more obvious, but I weigh only ~150 lbs. Plus I have a carbon fiber back and seat pan. It's a stiff ride. I imagine any difference between the TR3 and ZR2 as being analogous to having your tires filled to 130 psi vs. 135 psi -- a difference, but a very subtle one.

          I think the big difference is in aesthetics and there, for my money, the ZR2 is the sleeker of the two -- much less chair, much more me. I also prefer the wider diameter tubing of the ZR2 because it fills my hands more comfortably when grabbing onto the frame for transfers.
          stephen@bike-on.com

          Comment


            #6
            Originally posted by stephen212 View Post
            I'm presently using a fixed-back ZR2, which I am very happy with -- it's a great chair! I don't have any experience with the TR3 and wouldn't be able to offer a meaningful comparison between it and my ZR2 unless I had one that was identically configured. While it stands to reason that the TR3 would be more efficient, I remain, however, skeptical that the difference is anything other than subtle. Maybe if I were bigger and heavier the advantage in performance of a box frame chair might be more obvious, but I weigh only ~150 lbs. Plus I have a carbon fiber back and seat pan. It's a stiff ride. I imagine any difference between the TR3 and ZR2 as being analogous to having your tires filled to 130 psi vs. 135 psi -- a difference, but a very subtle one.

            I think the big difference is in aesthetics and there, for my money, the ZR2 is the sleeker of the two -- much less chair, much more me. I also prefer the wider diameter tubing of the ZR2 because it fills my hands more comfortably when grabbing onto the frame for transfers.
            Subtle = Negligible

            What about your Hall's versus your ZR2?

            Comment


              #7
              I think that because there are so many variables it wouldn’t be very meaningful to compare the two frame styles in a way that would show consistent and significantly measurable differences. Even things like temperature and elevation above or below sea level can be variables. I actually believe you could get these same slight differences between two or three chairs of the same type, configuration, and manufacturer. I have seen bearings of the same type and manufacture that I have held in my hand turn differently.

              I would suggest that you pick a quality wheelchair of the design best suited for yourself and configure that chair to be as light and free-rolling as possible. The efficiency of the chair doesn’t occur in a vacuum. The user is significant to this efficiency. The proper chair will give you the maximum leverage specific to your body type, strength, and needs.

              Comment


                #8
                My friend's Eclipse also have the caster float problem.
                Life is meaningles, though you create the purpose.sigpic

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                  #9
                  Originally posted by SCI_OTR View Post
                  What about your Hall's versus your ZR2?
                  My ZR2 is the smoother more efficient ride.
                  stephen@bike-on.com

                  Comment


                    #10
                    Originally posted by stephen212 View Post
                    My ZR2 is the smoother more efficient ride.
                    Just out of curiosity which is easier to perform a stable wheelie in?

                    Comment


                      #11
                      Originally posted by SCI_OTR View Post
                      Just out of curiosity which is easier to perform a stable wheelie in?
                      It's a slight apples-to-orange comparison at the moment because the Matrix back on my Halls is shortchanging my seat depth slightly. Presently the ZR2 is a little tippier, which I like. Otherwise I would say it's a draw between them.

                      I really like the "bullet" caster housing on the TiLites. It feels more solid to me than the bearings-in-housing style on the Halls.
                      stephen@bike-on.com

                      Comment


                        #12
                        Thanks for the info. I am asking as I'm thinking of getting a new chair. I currently have a titanium, thin diameter tubing, rgk with a box frame and I am thinking of getting a cantilever frame with 1.25" titanium tubing, a change from 26" wheels to 25" with the only other change in spec being the taper down to my footplate, which is staying the same width, being 2" wider at the top half to stop my legs rubbing when leaning forward to do pressure reliefs which makes my knees splay out.

                        I'm also thinking of getting the carbon fibre seat pan instead of the sling seat. Does the carbon fibre seat pan only add any noticeable efficiency, I've read it acts as subtle suspension when going over bumps too but would this be noticeable on cushions with a solid base ie a Jay 2?

                        I did notice a difference comparing the 5x1"and 4x1.5" frogs legs casters, in a frogs legs fork using the the lower mount height to keep the front stf the same and the 4x1.5" did not roll as well. I'm trying to figure out if other changes would be as noticeable?

                        Comment


                          #13
                          Originally posted by stephen212 View Post
                          It's a slight apples-to-orange comparison at the moment because the Matrix back on my Halls is shortchanging my seat depth slightly. Presently the ZR2 is a little tippier, which I like. Otherwise I would say it's a draw between them.

                          I really like the "bullet" caster housing on the TiLites. It feels more solid to me than the bearings-in-housing style on the Halls.
                          Agreed. I kind of see caster barrels as obsolete at this point.

                          Not that you would particularly care, but so far no manufacturer has perfected a way to easily true the fork stems on an adjustable model and ensure it stays put after a sustaining a harder impact. TiLite's "six shooter" design will stay put, but making this adjustment is much more difficult than it seems.

                          Although I have yet to tinker with it, Ki Mobilty's "Rack & Pinion" design looks promising.

                          Comment


                            #14
                            Originally posted by rob1 View Post
                            ... I am asking as I'm thinking of getting a new chair. I currently have a titanium, thin diameter tubing, rgk with a box frame and I am thinking of getting a cantilever frame with 1.25" titanium tubing, ... getting the carbon fibre seat pan instead of the sling seat. Does the carbon fibre seat pan only add any noticeable efficiency, I've read it acts as subtle suspension when going over bumps too but would this be noticeable on cushions with a solid base ie a Jay 2?
                            I'm too new in a chair to compare different seat setups BUT – excepting a combination of physical needs that demands the give and sag and constant readajustment of a sling seat –I can't imagine anything more sensible than specking a new chair with a c/f seat pan or adding c/f/velcro strips ala Stephen212.

                            I went with a Ti Composite (c/f) seat pan on my May/12 ZR, which is reinforced along the centerline by a composite fore and aft rib resting on a saddle post set upon the cross tube. Sitting directly on the pan is just like sitting on a barstool, so cushion (and perhaps a cantilever frame) is mostly all that will absorb what's between a rock and your hard place.

                            Cushions are a whole other thing, very user-dictated, but in my case a 2" Stimulite Sport eats up vibrations and bumps just fine. Sitting immobile for up to three hours is comfortably comfortable.

                            I would imagine the c/f strip configurations used by Stephen, toto and others, have a little more "give" than the Ti c/f pan and might be a better bet for certain other butts ... perhaps they'll chime in.

                            Comment


                              #15
                              Originally posted by rob1 View Post
                              Thanks for the info. I am asking as I'm thinking of getting a new chair. I currently have a titanium, thin diameter tubing, rgk with a box frame and I am thinking of getting a cantilever frame with 1.25" titanium tubing, a change from 26" wheels to 25" with the only other change in spec being the taper down to my footplate, which is staying the same width, being 2" wider at the top half to stop my legs rubbing when leaning forward to do pressure reliefs which makes my knees splay out.

                              I'm also thinking of getting the carbon fibre seat pan instead of the sling seat. Does the carbon fibre seat pan only add any noticeable efficiency, I've read it acts as subtle suspension when going over bumps too but would this be noticeable on cushions with a solid base ie a Jay 2?

                              I did notice a difference comparing the 5x1"and 4x1.5" frogs legs casters, in a frogs legs fork using the the lower mount height to keep the front stf the same and the 4x1.5" did not roll as well. I'm trying to figure out if other changes would be as noticeable?
                              Ah Ha! So you do have a pragmatic agenda.

                              A couple things to note...
                              A solid seat pan will raise your effective STF height by 1/4-1/2" so you will want to account for that in your specs if you go that route. I believe TexasWheelz discovered this the hard way when he first took delivery of his ZR2.

                              Another thing to keep in mind is that FrogLegs suspension forks behave differently on a cantilevered frame than the do on a box frame. This has to do with the fact that the caster housing isn't buttressed by a lower frame rail. If you lean forward and do not take this into account, compression of the elastomer combined with a slight compression of the frame will cause the front end to dip forward. If you do not react quickly when this occurs, the result will frequently be a transfer transfer endo. Models that have ovalized tubing connecting the caster housing to the front frame will be less likely to do this.

                              Of course, using the old school technique of reverse swiveling your forks can make he compression of the elastomer work in your favor.

                              With the vast majority of the chairs I spec, a 4 or 5x1.4" soft roll will usually suffice. A standard bearing fork, SlipStream fork, or UniTine fork will perform better in most situations, gives your a slightly tighter swivel radius, and will be less-costly to maintain in the long run. FrogLegs forks combined with an adjustable angle footplate may be recommended if the user has severe spasms that tend to be triggered by vibration of rolling over rougher surfaces.

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