18x17+1 85 Degree ZRA2 with Ride Custom Cushion

[SCI_OTR]

It has been a while since I've spec'd a custom rigid frame worthy of posting, but this one stands out. It is a very blue 18x17+1 ZRA equipped with an ADI Carbon Back and a Ride Custom cushion.



First the Chair...



18"W x 17"D
18" Custom Frame Depth
19" Front Seat Height
16.0" Rear Seat Height
85 Degree Front Angle
17" Seat To Footrest
V-Front End w/ 12" Footrest Spacing
14.5"-19" Folding Adj-Ht Back w/ Integrated Fold Down Push Handles
95 Degree Seat Back Angle
3" Center Of Gravity
2 Degree Aluminum Camber Tube
24" Spinergy LX Wheels/Schwalbe Marathon Evos/NaturaFit Handrims
Small Carbon Fiber Side Guards
Quickie Compact Scissor Locks
5x1.5 Frog Legs Aluminum Hub Soft Rolls

The Ocean Blue Metallic finish and Sapphire anodize package are nearly identical in color...



Now for the seating system. The backrest is a 10" high ADI Carbon back with Fixed Elite Hardware. An 18x16 Ride Custom cushion is used on the seat upholstery.



Wait a second, an 18x16 cushion on an 18x17 seat? That's what the folks at Ride Designs wanted to know. Absolutely, I told them. About 3/4" of seat depth is used by the ADI back so a 16" deep cushion fit perfectly. The confidence of my response had nothing to do with my expertise. Rather, when I performed the end user's evaluation, I used a nearly identical setup using a demo ZRA with nearly identical dimensions, a Roho JetStream Back, and an 18x16 Ride Evaluator cushion.

Ride Custom cushions are unique in that they rely on their size and shape to provide the surface area and contour needed to off-load forces away from bony prominences and redistribute those forces onto areas that are able to tolerate pressure. Ride Designs uses the term "Force Isolation".

The Brock material used to construct the cushion is very firm and since it doesn't compress, the result is a cushion that can cause one to sit higher than when on other cushions. This must be taken into account in a wheelchair's specifications--specifically STF heights, center of gravity, and seat to footrest height.

When done properly, how effectively is a Ride Custom cushion at providing force isolation? One way to tell is to place a "Ride gauge" at the lowest part of the cushion and determine if the ischial tuberosities are being subject to any pressure. It is basically a 1/4" thick layer of a powdery material that will easily indent should the ischium come into contact. So as not to waste our supply of gauges (and for dramatic effect), I decided to "test" the degree of force isolation on myself by replacing the Ride gauge with my smartphone...



I'm happy to report that my smartphone was not only intact, it was completely untouched. Try that with any other cushion.

On second thought, don't try that. It takes a professional to properly fit this cushion and more than the cost of a smartphone is at stake.

[petertan]

That is a sharp looking chair, SCI_OTR.

I see that you spec-ed a 10" ADI Carbon Back for a 16" rear seat height. Is there a reason why you did not put a 13" back instead seeing that is some space still between the bottom of the carbon back and the top of the cushion? And also why a Fixed Elite instead of a 2-Point Pro?

[SCI_OTR]

Originally Posted by petertan

That is a sharp looking chair, SCI_OTR.

I see that you spec-ed a 10" ADI Carbon Back for a 16" rear seat height. Is there a reason why you did not put a 13" back instead seeing that is some space still between the bottom of the carbon back and the top of the cushion? And also why a Fixed Elite instead of a 2-Point Pro?

2 point pro isn't available on the carbon fiber back in the US and I knew from my initial eval using the JetStream back that the the fixed hardware would not pose any issues.

Originally Posted by t8burst

What is the level of the person who is getting the chair? I have a 10'' jetstream and mine is a lot lower than that.

I issued it last week to an end user who I believe had a mid-thoracic injury. The back height has to do with some positioning considerations caused by some limitations in hip range combined with the characteristics of a Ride Custom cushion. If I can sit on the cushion without my ischials making contact with a smartphone at the bottom, it is reasonable to conclude I am sitting higher in the chair than would normally be the case on other cushions.

It may also appear somewhat higher due to the amount of contrast between the color of the chair and the darker seating components.

[t8burst]

What is the level of the person who is getting the chair? I have a 10'' jetstream and mine is a lot lower than that.

[Colin83]

Great looking chair

[Brianm]

Nice posting. I have a chair spec'd out in Ocean blue and while I have some different choices, it was great to see this one.

[amyk]

Originally Posted by Brianm

Nice posting. I have a chair spec'd out in Ocean blue and while I have some different choices, it was great to see this one.

are you getting a new chair? or are you like me and constantly speccing out new chairs? today im on the tx (again), just in case i ever want another folder......

[Brianm]

Originally Posted by amyk

are you getting a new chair? or are you like me and constantly speccing out new chairs? today im on the tx (again), just in case i ever want another folder......

I have been working with a rehab/Dr/DME for awhile now on getting a new chair, we are waiting on the insurance right now.

It is funny that when I went from my previous chair to my TR the differences were dramatic, so no wonder I fretted over the decisions. Now I want some subtle changes and I still fret over them.

Changes include, besides paint...

* Going from 19.5 front (really 19.75 with caster in bottom) by 16 rear to 20f and 15.5r; this is where I struggle most. More later.

* Regular forks with 5x1.5 instead of FL forks and 4x1.5

* 85 degree front instead of 80

* +0.75" instead of +1"

* Standard footrest instead of flip back footrest

* ADI solid back

I think that covers it.

I want a little more foot clearance so going a little higher in the front and not using the flip-back footrest which has a bar around back.

I also want to be down in the wheels a tad more, hence the 0.5" lower in the rear. This is where I fret; this is quite a bit of dump and while I think I will be fine using the chair this way, I wonder if hard on the body in any way. Leaves me wondering if 25" wheels would be better to get the same result.

[Bluefairy]

Originally Posted by Brianm

I have been working with a rehab/Dr/DME for awhile now on getting a new chair, we are waiting on the insurance right now.

It is funny that when I went from my previous chair to my TR the differences were dramatic, so no wonder I fretted over the decisions. Now I want some subtle changes and I still fret over them.

Changes include, besides paint...

* Going from 19.5 front (really 19.75 with caster in bottom) by 16 rear to 20f and 15.5r; this is where I struggle most. More later.

* Regular forks with 5x1.5 instead of FL forks and 4x1.5

* 85 degree front instead of 80

* +0.75" instead of +1"

* Standard footrest instead of flip back footrest

* ADI solid back

I think that covers it.

I want a little more foot clearance so going a little higher in the front and not using the flip-back footrest which has a bar around back.

I also want to be down in the wheels a tad more, hence the 0.5" lower in the rear. This is where I fret; this is quite a bit of dump and while I think I will be fine using the chair this way, I wonder if hard on the body in any way. Leaves me wondering if 25" wheels would be better to get the same result.

More dump is in no way good for you!! I would go with 25" Wheels instead.
I decreased dump from 4" to 1 1/2" And I have never felt or looked better.
So many people fail to realize that we are not meant to be folded in to a wheelchair, dump is to provide stability, but stability also comes from a proper fitting chair. A chair that is not too wide and not too low and with a reasonable amount of dump. Side guards provide better stability than 4-5" of dump.

From the picture in your avatar you look to be almost 6' tall, you could even go to 26" wheels. I'm 5'2" and I’m on 26" Day wheels. My seat front is 530mm/20" and my rear seat height is 490mm/19.2".

I think that people are miss informed when it comes to dump, I know a few quads that sit in 1-2" of dump and they are very comfortable in their chair.

I've attached my chair specs, take a look.

This set up is much like what you are describing, only with bigger wheels and less dump. I'm an L3 Para and this chair suits me very well in daily use.
With the 26" wheels you get a good amount of wheel to push. Also note the ergo seating for proper pelvis alignment. And the welded side guards.

[tooley]

Originally Posted by amyk

... are you like me and constantly speccing out new chairs?

I used to be like that. Now I'm continuously tweaking existing chair designs. Here's my Lasher BT-Mg revised with a totoType pushbar and RB Dino's.