Suggestions for new chair

[daveh0]

Greetings! So my everyday use chair is the original TiLite X I left Craig Hospital with 13 years ago. It's taken some abuse over the years but for the most part has served me well... and my Medicare Advantage plan has been good about paying for most repairs. However, i currently have access to funding for a new chair... a new chair on par with or higher-end than what my TiLite was back in 2003, so I'm very excited about this opportunity. I'll be coordinating it all through the fine folks in Craig's outpatient services department, but there's a waiting period so I have some time to do a little research and hopefully gather a little bit of first-hand intel before I get in to see them.

My primary criteria is that the chair is ultra-light and ultra-portable. I can currently pick up my TiLite and place it in the trunk of my Subaru wagon without the need to fold or break it down at all. I'd like to keep this ability. I also travel by plane 4-7ish times per year. In these cases, everything is broken down as much as possible and gate checked - haven't had anything go TOO, too wrong and need to make sure this new chair is durable enough to keep that streak alive. On a secondary level, I'd love my new chair to be able to handle some challenging terrain (or at least a bumpy sidewalk) better than my current one - things like suspension systems are starting to look interesting. At the same time, I realize anything of that nature will add weight. I have a FreeWheel... perhaps that is the solution to stick with?

I've been looking at the newest TiLite models... quite closely at the ZR. I have a feeling that this is the direction in which I'll be pointed at Craig Hospital... quality chairs, proven time and again, on (or not far off) the forefront of some of the newest design/innovation, etc, etc. But I know there's more out there and since I'm in the unique situation that I am, I'd like to at least check and see if some of these newer horses deserve to be in the running. A close friend, who knows a lot about engineering in general, mountain bikes and sports cars (wheelchairs specifically, not so much) believes carbon fiber is the way of the future. I found this post: http://www.apparelyzed.com/forums/to...s-a-good-idea/ to be quite informative. It's from 2014 so I'm sure there's been some more said by some equally knowledgeable folks since then.

Does anyone use a chair like the Carbon Black, Panthera X, any of the Motion Composites models or anything in that league? Anyone's thoughts, knowledge and/or experience with carbon fiber frames as opposed to titanium as it pertains to weight, durability and compactness would be great to hear. Is carbon fiber a sensible material for an everyday-use wheelchair or should it be limited to aircraft, fast cars, mountain bikes and chairs designated specifically for engaging in one's sport?

[Mize]

Carbon fiber is far less tough than alloy particularly with respect to impact damage. Toughness is the measure of a material's ability to sustain damage but still function. While carbon composite are very strong, they are not very tough and a single hammer-like blow can be fatal.

[Andy]

I second the questioning of CF in a wheelchair design. It might be fine if all you do is ride it, but looking how beat up and grind-marked my TR3 is from breaking it down, dragging it on the ground, and ramming into things, I suspect that a CF frame could not survive what a metal frame can.

[daveh0]

...they are not very tough and a single hammer-like blow can be fatal.

If I understand correctly, that blow would have to be applied directly to an individual tube. If so, while a direct blow could be fatal, something more realistic, like the chair colliding with another object or possibly being dropped would not be equally as fatal. Is this accurate?

[t8burst]

I have a TR with a non folding back and a CF camber tube. Without the wheels and cushion it is 9 pounds I can easily pick it up with one arm, an all CF chair might be cool but I don't know if I would trade the durability of titanium for a couple of pounds.

[daveh0]

I've definitely been hearing a lot about durability being an issue with a CF frame. I just call that into question considering a lot of very high end downhill mountain bikes are made of CF. I know we use our chairs far more than an average mountain biker... and their bikes have insane suspensions, whereas our chairs have none, but I still have to think those bikes take a far worse beating. Does anyone know where/when/how the weakness of a CF frame would rear its ugly head?

[Black Alloy]

I found this post: http://www.apparelyzed.com/forums/to...s-a-good-idea/ to be quite informative.

daveh0,

My comments in your referenced post are more true today than the day they were made. It's not a question of materials choice, it's a question of engineering choices. The carbon fiber chairs I've built have performed flawlessly for many years under very demanding conditions. I am absolutely confident that a carbon fiber everyday chair can be built that is superior to metal frame chairs in every way. I can't guarantee that anyone else is doing it.

[Brad09]

I agree, carbon fiber technology has come a long way. Most super cars these days are using carbon fiber for the ENTIRE structure of the car (both frame and body). They arent going to build something that does 250 mph out a non durable material.

[daveh0]

Black Alloy and Brad09, thanks for the input. THat's definitely been the general direction of my thinking with the more research I conduct, but the challenge still lies in the task of finding a CF, everyday-use chair that actually *has* been engineered in such a way as to put the material to use "properly". Of course the manufacturers will tell me they are doing this and not being an expert in the field, I have very little grounds on which to contest their claims.

What would/should one look for in evaluating whether or not proper design considerations have been made for a CF frame? What are the tell-tale signs of poor engineering? How can I tell by looking at and/or sitting in a chair that it's not going to fail catastrophically when the baggage attendant at the airport doesn't treat it with as much TLC as should be when loading it into the belly of the plane... or any of a dozen other scenarios come to be in which my chair's durability is put to the test? My fear is that there are no answers to those questions that would serve much practical use to the average "civilian" gimp... like me.

Any knowledge of any CF chairs commercially available today that are known/proven to be able to handle the rigors that my current titanium frame has being doing for the past 13 years? I don't feel comfortable taking the manufacturers' word for it. First (and maybe even second) hand knowledge and/or a trusted 3rd-party review will be required for me to feel it a prudent, worthwhile investment. I wish the technology (and it's use with specific respect to wheelchairs) were a bit older so more of this could exist. But if anyone does have any of this type of info to share, please lay it on me - I'm all ears. I *want* this to be the right direction.

[Brad09]

The only carbon chair I've seen in person is the panthera x. A guy in my neighborhood has one. Unfortunately I don't know what to tell you as far as real world durability goes and if these manufacturers are engineering these chairs to the level we need them to. That's a good question you bring up. I guess the only way to know is from the experience of others that use a carbon chair everyday and put it through the paces. Most people want a carbon chair because it makes car transfers, etc. easier because of the weight, but for me its making the chair lighter to push and the less effort to do it that would make the biggest difference. I'll be looking into these the next time I'm up for a new chair.

[Oddity]

I tried my buddy's Panthers X and I didn't notice a difference vs pushing my Lasher BT-Mg. Then I did the math. I weigh 170lbs. My chair weighs 21.5lbs. With my cushion the Panthera X weighed 16lbs. Total rolling package 191.5lbs and 186lbs, respectively. Then I realized why I couldnt notice much of a difference. There really wasn't much of difference to notice. It was when lifting the chair that the difference was remarkable. 5.5lbs is ~25% difference on a 20lb chair but on a nearly 200lb total package it's only a couple percent.

[Brad09]

That makes sense, however I've been able to tell a difference in pushing a lighter chair, even the same chair with lighter wheels. I only weigh around 140, so the percentage of weight difference may be a little higher, but not much. I guess it varies person to person. But in theory a lighter chair should take less effort to push/maneuver.

[Black Alloy]

Oddity is exactly right, there is very little advantage realized with respect to ease of pushing a lighter CFRP wheelchair. There can be; however, quite a noticeable improvement in push efficiency based on frame rigidity. In order to save weight, many metal frame chairs are simply omitting structural members and using cantilever designs. The lack of a fully boxed frame not only decreases frame rigidity, but also changes the location and magnitude of load bearing stress.

I read more than a few posts about caster flutter problems on various chairs, that may well be the lack of support for the caster fork stem housing rather than a problem with the caster assembly itself.

The best reason to choose a carbon fiber chair in general is low transfer weight without sacrificing strength. I load/unload my chair an average of 10 times per day. Over 16 years that's nearly 60000 times I've had to lift my chair with one fully extended arm. The difference in effort required and shoulder fatigue experienced in the 5 years I've been using this same carbon fiber chair have been incredible. It also makes loading/unloading my chair much easier on the other people in my life who occasionally have to lift my chair into the back of my SUV.

As to which carbon fiber chair to choose, there's really no easy way to evaluate the quality just by looking at one. If you have an eye for engineering, you can pretty easily see if an overall design would be inherently "strong", but it still depends largely on the materials used and the layup schedule.

Try and talk to people with actual experience with a particular chair and compare your needs to theirs. Keep in mind that wheelchairs are designed to perform the activities required for personal mobility and the related abuse of daily life. Noone can guarantee that any wheelchair will withstand extreme abuse from mishandling.

[scurl]

I have one of these http://progeo.net.au/wheelchairs/rig...oker-evolution simply the best chair I've ever had. A mate has the carbon version.

[daveh0]

Most people want a carbon chair because it makes car transfers, etc. easier because of the weight, but for me its making the chair lighter to push and the less effort to do it that would make the biggest difference.

Both of these describe my exact situation. With insurance companies (or *most* insurance companies) refusing to pay for ultra-light chairs, it seems like too big of a risk to take to learn the hard way that CFChair XCF can't handle the knocks and dings that occur when an unforeseen pothole partially swallows the chair and sends its occupant flying in the other direction. I learned the hard way that my Titanium frame CAN in fact handle this and many other types of trauma. I also know that there is a lifetime warrantee on that Titanium frame.

Statements like this one (not even in the fine print) make me wary:

Carbon Fibre is a very strong material but sensitive to impact and hard shocks. As an example, a fall backwards in the wheelchair against a hard surface can cause damage to the back frame. Damages caused by external force are not covered by warranty.

Again, I *hope* I can be proved wrong and a CF chair will end up being the right one for me.