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Anyone have a 75 degree front angle?

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    Anyone have a 75 degree front angle?

    My TiLite with a 90 degree front angle has the front tubes about 6" ahead of the seat sling. This extra length interferes with transfers. I would like to minimize this distance. The only way to do this without changing anything else is to decrease the front angle as much as possible. I calculate the angle can be less than 75 degrees. It would require a pretty tight turn radius but it may be possible. Before I commit to this, I would like to see some pictures. Does anyone have a picture of a TR with 75 degree front angle?

    By the way, an additional benefit is that luggage and shopping baskets rest better on luggage racks at 75 degrees than 90 degrees.
    Attached Files
    Last edited by August West; 30 Sep 2017, 5:48 PM. Reason: added drawing

    #2
    Mine is 85 so not much less than your current chair. One thing to consider is you are bringing the casters closer and closer to the wheels. I know I already have to be careful about leaning forward in my chair if the casters are rotated toward the back as I can lift those back wheels off the ground fairly easily.

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      #3
      I have 80 or 85 degree front, not sure which. When I had 75 I found it more difficult to transfer as front of footrest bumped my transfer target.

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        #4
        I have a 2" tapered seat and custom tapered footrest so that my footrest inside width is just adequate for my widest shoes. I find a narrow footrest helps me with transfers, no big, square front end.

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          #5
          Originally posted by funklab View Post
          One thing to consider is you are bringing the casters closer and closer to the wheels.
          Good point. There's that trade-off.
          Last edited by August West; 30 Sep 2017, 7:48 PM.

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            #6
            Originally posted by ancientgimp View Post
            I have 80 or 85 degree front, not sure which. When I had 75 I found it more difficult to transfer as front of footrest bumped my transfer target.
            I know what you are saying. The solution is to make the frame depth shorter than the seat depth so that the bend starts under the cushion rather than in front of the cushion. Otherwise, the footrest will stick out more.

            I've tried the narrow footrest (11"). The problem is that I like to transfer out with my feet on the footrest for the additional height. In that case, feet get trapped in the narrow footrest during the transfer. Hence, I like the footrest to be 12" rather than 11". For transferring in I'm going with a flip-back foot rest, which enables getting closer.
            Last edited by August West; 30 Sep 2017, 7:53 PM.

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              #7
              i was going to say that i think they would still start to bend the frame for the 75 degree angle at the same point as the 90 degree one so as a result the footplate would stick out further, if they start to bend it further back it could interfere with your cushion etc

              Comment


                #8
                From previous threads here, mostly by SCI_OTR, I clearly recall him indicating that Tilite adds +1" to the tubing, prior to the bend, when selecting a 90deg. frame. So, switching to an 85deg frame would start the bend 1" farther back.

                Perhaps an even more important measurement (at least for fit), is what's been called "occupied frame length", which is the distance between the leading edge of the backrest and the leading edge of the footrest.

                Altering the front end angles will change this, often significantly. While you may end up with the clearance you want at the top of the bend, your feet and knees will be bent differently and in different locations than they are currently.

                I would suggest starting with the desired "occupied frame length" and allowing the other dimensions be derived from that.

                This could enable having the most possible top side clearance while maintaining your seated fit.
                Last edited by Oddity; 1 Oct 2017, 11:42 AM.
                "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

                "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

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                  #9
                  Originally posted by rAdGie View Post
                  i was going to say that i think they would still start to bend the frame for the 75 degree angle at the same point as the 90 degree one so as a result the footplate would stick out further, if they start to bend it further back it could interfere with your cushion etc
                  Yes it could. In my case, the frame depth (backrest front to start of bend) is 1" longer than the seat depth (backrest front to seat sling front), which is 1" longer than the cushion. I could reduce the frame depth by 3" and the bend would start just 1" behind the cushion (see the picture below) resulting in a 1/8" height difference between the cushion front and bend (4" radius). That's negligible.


                  Originally posted by Oddity View Post
                  From previous threads here, mostly by SCI_OTR, I clearly recall him indicating that Tilite adds +1" to the tubing, prior to the bend, when selecting a 90deg. frame. So, switching to an 85deg frame would start the bend 1" farther back.
                  Correct about their older order forms. Their present order forms specify 0.5" additional tubing regardless of angle unless otherwise specified. But their latest drawings still show 1". Aren't the drawing supposed to be to scale?

                  Originally posted by Oddity View Post
                  Perhaps an even more important measurement (at least for fit), is what's been called "occupied frame length", which is the distance between the leading edge of the backrest and the leading edge of the footrest.

                  Altering the front end angles will change this, often significantly. While you may end up with the clearance you want at the top of the bend, your feet and knees will be bent differently and in different locations than they are currently.

                  I would suggest starting with the desired "occupied frame length" and allowing the other dimensions be derived from that.

                  This could enable having the most possible top side clearance while maintaining your seated fit.
                  Excellent recommendation to start with the occupied frame length and then backtrack. Doing that and reducing the frame depth by 3" would result in an 80deg angle. Or reducing the occupied frame length by 2" and reducing the frame depth by 3" would result in an 85deg angle.

                  Regardless, you are correct, the angle is secondary. The primary dimensions are occupied frame length and frame depth.

                  By the way, in case you are wondering why I am talking about a TR but showing a ZR drawing, this is the CAD drawing that TiLite sent. The second CAD drawing which usually costs $75 is going to be on them.
                  Attached Files

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                    #10
                    looking at those cads id rather have the 90 degree version as knee protectors :P you could tell them your cushion is 1 - 2 inches shorter than it actually is? then when you put it on you will have the 90 degree frame and it will start as it leaves your cushion, does that make sense?

                    Comment


                      #11
                      I'm learning new stuff. I always thought the front downward bend started at the same place regardless of front approach angle, and that by choosing a 75 degree over a 90 degree simply made the chair longer. I stand corrected. I have a T4 SCI. My first chair was an old box style Quickie GPV with a 75 degree front angle and a very mild dump. I was quite stable in that chair but the chair was a bit too long in certain circumstances. For my next chair after that I chose a Kuschall Champion with 24" rear wheels and a 90 degree front angle hoping to reduce my footprint because I had been experiencing issues fitting into bathroom stalls and couldn't get close enough to the table in some restaurants. The Kuschall definitely had a smaller footprint but I kept falling out forward when my front casters would fetch up on a small pebble or I tried to pick something up in front of my chair. To solve that problem I dialed in a lot of dump. While that solved my stability issue, it made me so short that I couldn't reach much at the grocery stores. I also couldn't make my casters perpendicular to the ground (because back then the assemblies where welded in place like the Invacare Top Ends) so my front would dip and raise when going from forward to backward. Anyway, I really learned a lot from that Kuschall chair--mostly how not to order a chair. It was a really was a well made high quality chair. ...I just didn't know enough about ordering chairs at the time.
                      Last edited by fasdude; 2 Oct 2017, 12:44 PM.

                      Comment


                        #12
                        Originally posted by rAdGie View Post
                        looking at those cads id rather have the 90 degree version as knee protectors :P you could tell them your cushion is 1 - 2 inches shorter than it actually is? then when you put it on you will have the 90 degree frame and it will start as it leaves your cushion, does that make sense?
                        Makes perfect sense. But there's a catch. Reducing the seat tube length 2" with a 90 degree angle places the front caster under the rear wheels, which presents stability issues. Hence the more you reduce the depth the more you have to reduce the front angle.

                        Comment


                          #13
                          Originally posted by fasdude View Post
                          I'm learning new stuff. I always thought the front downward bend started at the same place regardless of front approach angle, and that by choosing a 75 degree over a 90 degree simply made the chair longer. I stand corrected. I have a T4 SCI. My first chair was an old box style Quickie GPV with a 75 degree front angle and a very mild dump. I was quite stable in that chair but the chair was a bit too long in certain circumstances. For my next chair after that I chose a Kuschall Champion with 24" rear wheels and a 90 degree front angle hoping to reduce my footprint because I had been experiencing issues fitting into bathroom stalls and couldn't get close enough to the table in some restaurants. The Kuschall definitely had a smaller footprint but I kept falling out forward when my front casters would fetch up on a small pebble or I tried to pick something up in front of my chair. To solve that problem I dialed in a lot of dump. While that solved my stability issue, it made me so short that I couldn't reach much at the grocery stores. I also couldn't make my casters perpendicular to the ground (because back then the assemblies where welded in place like the Invacare Top Ends) so my front would dip and raise when going from forward to backward. Anyway, I really learned a lot from that Kuschall chair--mostly how not to order a chair. It was a really was a well made high quality chair. ...I just didn't know enough about ordering chairs at the time.
                          All good points. It's a trade-off. There's no perfect solution. Another problem with casters not normal (perpendicular to the ground) is that they resist turning side to side, which stresses your wrists.

                          Comment


                            #14
                            Originally posted by August West View Post
                            Makes perfect sense. But there's a catch. Reducing the seat tube length 2" with a 90 degree angle places the front caster under the rear wheels, which presents stability issues. Hence the more you reduce the depth the more you have to reduce the front angle.
                            you cant have both im afraid, i made my chair as small as possible width as well as length and im glad i did as if it wasnt for doing that theres places i would of struggled to get to, i got more dump in mine now so less likely to tip forward, i compromised plus never thought of what if i tip forward, the further out the castors the more stable you will be, also something that might not have been mentioned is the rear wheels, the more forward you can have them the shorter the chair, but then you will have a tippy chair and also the size of the rear wheels, every little helps :P

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                              #15
                              Originally posted by rAdGie View Post
                              you cant have both im afraid, i made my chair as small as possible width as well as length and im glad i did as if it wasnt for doing that theres places i would of struggled to get to, i got more dump in mine now so less likely to tip forward, i compromised plus never thought of what if i tip forward, the further out the castors the more stable you will be, also something that might not have been mentioned is the rear wheels, the more forward you can have them the shorter the chair, but then you will have a tippy chair and also the size of the rear wheels, every little helps :P
                              I have to reduce transfer distance because of my shoulder. Transfers never used to be a problem until recently (34 years post injury). I don't suppose it's going to get any easier over time. The critical dimension for me is the distance between the front of the cushion and the front of the wheelchair so that I can reduce transfer distance. For this I am willing to live with a wheelchair that is a little forward tippy. There will be a learning curve to adjust to the changes in balance. I have to be careful not to take a header. Otherwise, like all things over time I will get used to a wheelchair that is forward tippy.

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