Hey everyone,

My name is Adam Silverstein and I am an senior undergraduate student at Savannah College of Art and Design, studying industrial design. I have been inspired by all the stories I've seen on this forum, and especially captivated by the extreme sports. For my senior thesis, I have been planning to design a manual wheelchair specifically for use in a skate park. I know there are some are a few members on this forum who already do this. I see a great deal of potential in this sport, and I hope by designing a wheelchair like this, more people would have the opportunity to experience it. I was really just hoping to get any feedback I can. For anyone who has experience with this: what they like about their chair, what they don't like, and what they wish a chair could do. I do realize that this sport is not for everyone, but any thoughts you have on this subject would be so greatly appreciated.

If you are interested in seeing some of my past work it can be viewed here: http://coroflot.com/asilver It needs to be updated, but it will give you a general idea.

Thank you so much for taking the time to read this.

Adam Silverstein

Tho I may not be as interested as some others, in a skate-park chair,, I'm sure that some new inovations in suspension design would benifit any chair user.

The key, I think, would be keeping it compact and strong,,, weight being of lesser concern,,, to a point.

A lot of dump and pinch, to keep the rider in position, and probably a frog leg like setup for the casters, to give a little flex in the front.

Just some odd thoughts,,, hope they are of use to you.
ed

I don't know about the suspension, if your going to catch any air the rebound could launch you out, although I guess you would probably be strapped in so it wouldn't be that much of a factor. We need Santa Cruz Surfer in here as I'm sure he could give you some ideas.

Thank you both for getting back to me!

It seems like suspension would be pretty vital in dampening impacts on landings, though, like you said, it is important to tune the suspension's rebound to the right point so that your not bouncing around everytime you land. The suspension will also play a part in allowing users to transfer wait while pumping on the ramps, and provide extra pop while launching.

Most sport wheelchairs as well as all wheelchairs with rear suspension now seem to be built using a solid rigid frame. I was wondering if anyone has any complaints about rigid frames as far as transporting them goes. Is it okay to stick with a rigid frame, or will this make for extra difficulty when bring the chair to the park?

Again thank you so much for your input so far, please keep it coming.

Adam

If it's to be a single purpose chair,,, like for basketball or rugby,, it will certainly need to be a rigid chair. It's going to take a lot of punishment,,, not all maneuvers will be completed successfully.

Most people who use these "special" chairs, will be using their everyday chair to get to the venue, than transferring to the sports shair. The ability to dismantle and drag across, won't normally be an issue. Placing the chair into the back of a pickup, or into the trunk of a car might be,, to a point.

Consider making the suspension easily adjustable, to allow for different weights and preferences. Some may want more "pop" than others,,, and different moves may call for more or less give.

Some form of independent suspension, might work well.

ed

Edlee,

That's a great point, I've spent the last couple days looking into different suspension types that would allow for this. It seems that an air spring and damper setup would give the best on the fly adjustability as well as relatively lightweight. There is also specially formulated elastomer suspensions that can would eliminate an mechanical parts, however they are fixed spring rates and rebound.

After some more testing in the local skatepark, it seems that the geometry of the wheelchair may need to be modified for optimal performance. Pushing the weight further back over the rear wheels would allow for easier weight transfer. A wheelie bar could be placed in the back allowing new users to get comfortable with the new weight distribution. The ability to easily get the front wheels off the ground in a wheelie position will also help with setting up to drop in on the quarter pipe.

Let me know what you guys think about this and please keep the ideas coming!!!!!

Thank you so much,

Adam

Hi Adam!
I was just wondering have you ever thought of designing wheelchair that could be used as a manual and electric (on demand) at the same time? I am currently working with some friends who own Metal Shop on designing it. It should be light, but with enough torque to move me around on the steep hills or streets! And also, battery should last for about 5-6 miles with one charge.
Something like Zinger wheelchair but without "roll-drive" but rather "chain-drive". Just wondering! Thanks!

Hey Zinger,

It's funny you mention that because I was originally going to design that for my senior thesis. I was hoping to utilize a dynameter in each wheel which would recharge the motors as the wheels spun in manual mode. Then when the power assist was needed it would use the stored energy to move the chair. I never got too deep into that research, so I have no idea if that's feasible at all. I was actually pretty impressed by the range of power assist products that have started emerging like the zinger.

Your "chain-drive" system sounds like a cool idea. You could get into using different gears with it to really optimize performance. Best of luck with that it sounds like a fun project!

Adam

Hey Adam, i'm sorry it's taken me so long to back to you on this, i've been on tour surfing the pat couple of weeks. i'd love to assist you in this design in any way I can. Let's talk sometime soon and discuss things.

Cheers, Christiaan

Adam,
thanks and I wish you good luck and success with your extreme wheelchair design as well

Hey Christiaan,

Glad to hear back from you! Hope you had a great time surfing, that sounds amazing. It would be really great to talk to you more about this project. Your experiences and insight are going to be incredibly valuable in this design. I'm sure we'll be talking on this forum, but if you ever want to email me you can at asilver22@gmail.com And that goes for everyone else as well.

I'm supposed to be posting my progress on a blog for the class, so in the next day or so I will post a link to it if anyone is interested.

Thanks again,

Adam

Well, here is my skatechair...It's a highly modified per4max shockwave, it run's a pair of custom tuned Fox Float R shocks with adjustable compression and rebound dampening. Reinforced frame tubing courtesy of my boyz at Santa Cruz Bicycles, Spinergy SLX rims with hard anodized hubs, Kenda Kevlar tires, Frogleg front suspension forks, ADI carbon fiber seatback, Supracore Sport cushion, custom made foot plates/buckle straps and all of the hardward was swaped out for ARP coldforged stainless steel...Thats all I can think of at the moment, if you have any questions, please feel free to ask!

Christiaan, that skate chair of yours looks awesome! (Offtopic, but I recently requested funding from the Assistive Devices Program we have here in Ontario for a pair of Spinergys--I hope I get them, am excited to give them a go. And just put Kenda knobby tires on my chair last month--love 'em! Was previously using mainly Primo tires but now I think I may switch over to Kendas entirely.)

Adam--that's kick ass that you are going to design an extreme chair AND that you're asking for our opinions. I think that any company/person who makes/designs chairs should be all over asking users for their input. It would probably greatly improve the design of a lot of the chairs that are out there.

THAT LOOKS AWESOME!

Wow, that thing is beautiful.... Thanks for putting up such detailed pictures of it.

I guess to start I have to ask the obvious questions... What is your favorite part of that chair? What about that chair don't you like or wish could be improved?

Also, I'm curious as to how often you adjust the suspension settings?

Thanks man,

Adam

Hey guys. I set up a blog with a little bit of my work. I will be uploading everything I've got so far throughout this weekend... I'm realizing I've got a LOT of work to do haha.

Extreme Wheelchair Blog

Thanks as always,

Adam

Some set up, SCSS,, have you any pics of you in action? I'm always impressed by the lengths some will go for a rush,,,, and envious, too.

Adam, I think you have gotten a good advisor, in SCSS, to help with your project. First hand experience is always better.

Looks like, from your blog, that you were going for some first hand experience, yourself,,, now you know why a chair for this purpose has to be pretty robust ( hope that word works)
You can certainly see, by your launch efforts, that standard anti-tip bars won't be feasible. Only practice will prevent faceplants,,, but not always.

Keep at it, guy,, and I liked that single spoke thing you showed,, might be a bit bottom heavy for wheeling, but it sure would look nice.
ed

Hey thanks Edlee...And Adam, Ed is absolutely right about the anti-tip bars, they will do nothing but cause brutal faceplants!... In order to successfully drop into a bowl or pool, there are several aspects of the drop that have to be taken into consideration.

1. Height of the overall drop

2. Amount of "vert"

3. Angle of the transition
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1. The height of the overall drop is going to dictate how much suspension travel you will need. Without suspension, any ramp over 6 feet can cause compression of the spine upon impact. Having the suspension not only saves your spine the stress of impact, but also saves your chair from metal fatigue over the long run...Another benefit, is when your shocks are tuned correctly, it will accelerate you out of the transition when you land. Given the fact we can't use our legs to pump the transition, this is a major plus!

2. On more advanced pools and bowls there will be true "vert", this must be taken into account when making your drop, otherwise too much force upon entry can easily cause you to overshoot the transition and impact the flat ground...Ouch!

3. The angle of the transition is going to dictate at what angle your front wheels will need to be in order to make a clean landing...A general rule of thumb; The steeper the transition, the lower the front wheels need to be upon drop.
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Now, the biggest fundamental flaw in your graphic depiction, was the angle of entry... It is critical that you "wheelie" into the transition. Now this is where the math can get a little complicated; Depending on the persons level of injury (ie how much trunk control they have), they will need to place anywhere from a 85-110 degree angle (depending on the transition), into the tilt of your front wheels as it relates to the angle of your back...However, no matter what the level of injury, the rear wheel axle MUST be tuned within a 1/4 inch plus/minus of your spinal center of gravity (usually T5-T6)...Your rear axle is the fulcrum point from which all chair control is derived, so incorporating the suspension so that it maintains the frame geometry upon full compression is critical. Also, lowering the center of gravity as much as possible, dramatically increases stability!


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LOL, there are so many subtle techniques that are necessary in order chairskate well, it is almost impossible to for me to explain them here without writing 10 pages. Hopefully though this gives you the basic concept...Here is a video as well that will hopefully help you grasp what i'm talking about.

wow.. I'm completely amazed by this!!! LOL That just looks like soooo much fun!!!!! Very nice vid!!!

Thanks Edlee for the feedback. I updated the blog with a model of that single spoke design so you will have to let me know what you think.

Wheel Rendering

Christiaan, you are amazing. Thank you so much for these detailed insights. It is so great to have someone with your experience working with me. I am definitely going to have to rethink the geometry of the chair and my hypothesis on weight distribution.

Something else you brought up was "Another benefit, is when your shocks are tuned correctly, it will accelerate you out of the transition when you land. Given the fact we can't use our legs to pump the transition, this is a major plus!" This idea of pumping to maintain momentum, is one of the essential aspects of sports in the skatepark. From watching videos and trying it myself, I have found that this is much more difficult to do in the chair. If there is a way to improve this sports potential could really be unleashed. I have a couple ideas, to run by you all in the next day or two, but if anybody else has some thoughts, I'd love to hear them.

Again, I can't thank you all enough for your help. Please keep it coming.

P.S. If it is alright with everyone here, I was hoping to post a link to this thread on the blog. Your input has been vital to this project, and I would like others to see it. Let me know if anyone has any objections.

Thanks

Adam

Right on, it's no problem at all...I've been doing design R&D for quite some time now, so it's something I definitely enjoy! I took a look at your single spoke rim and while I think it is a beautiful design and would be great for everyday use, it's unfortunately not going to work at the skatepark...



The single spoke design lacks the structural integrety, to take on the severe lateral stress's posed by chairskating. Your four spoke design would be a far superior candidate for the park, being that the torsional stress could be evenly distributed across all four spokes!

As far as a "show" chair goes, your carbon flex Tri-Spoke rims are a killer design, very innovative!!!

Thanks for the kind words!

Yea, as much as I liked the idea of a single spoke, I knew it wasn't going to be best suited for this application. I have actually been working on a model of the tri-spoke. Ideally the wheel's spoke design would allow a slight amount of travel, which would help dampen heavy impacts... We'll see though.

Cool blog, Adam! I'm totally excited to see how the chair shapes up. Too bad you can't design kick ass chairs for all of us here on the forum!

And Christiaan, I am gonna come to Santa Cruz so you can give me some chair trick lessons! That vid of yours makes me wanna go surfing. Like ASAP!

Well, if you need anyone to test it out for you and give you design feedback, let me know...Looking at your tri-spoke design, have you considered using a elastomer center cuff around the hub, to buffer the flex of the carbon spokes?

T.O. Well, i'm on tour right now and won't be chilling at home for a few months...If your around and available Oct. 10th though, i'm putting on a TWSA in Santa Cruz if your interested? ;)

I might take you up on that! I'm definitely going to do a TWSA event or two this year and I'd love to go to yours! It will kick ass, I'm sure. But then you gotta promise to ski with me in Mammoth next season!

T.O. if I ever get a chair to go into production, I promise you all will be the first to get prototypes haha

I actually did consider working elastomer into the wheel design. My only worry is if there is too much movement in the elastomer, it will interfere with responsiveness of the chair. It would have to be very subtle.

Well, if you just run a buffer coating around the inside of the hub flange. It would not only make the level and amount of flex more consistent/predictable, but also add to the overall dampening qualities and longevity of the carbon spokes...I know this is a crude picture, but bear me out.

Great point Christiaan,

I think that really is going to be the way to do it. Right now I'm still working on modeling the wheel, so I will let you know when it's done.

I also updated the blog with an idea of simple way to help gain speed in the chair. It's just a quick idea I had, but could develop into something cool. Let me know you guys think.

New Idea

Heheh, sweet!!!


Oh, Christiaan, I forgot to ask you about the sideguards on your skatechair. Are those Ti Lite ones? In the Quickie Ti thread over in the Mobility area, I've been talking about getting higher sideguards for my chair. The ones on my chair that Quickie makes are crap. This is off-topic from this thread so maybe you can PM me or let me know in the Ti thread about them so Simon doesn't get mad at me for highjacking the thread?

Hey Adam, well the levers and gear drive systems have already been developed. And while they would work great for high level para's and quads during everyday use, they would be more of a hassle than their worth in the skatepark. The most essential aspect of chairskating, is being able to manipulate your rims upon turning, pivoting and wheelie'ing... By adding a gear drive and levers to this process, it over complicates the ability to effectively balance the chair during wheelies and other tricks...Not to mention, giving you one more thing to impale yourself on.




T.O. Yes they are older Ti light side guards, I like them because they are billet aluminum and give my hips far more "pinch" than plastic side guards...Not to mention, they look cooler!

Wow they've thought of everything already haha.

I do feel like with a few changes, mainly to the handle design, a system similar to this could be beneficial to the sport.

I guess it's back to the drawing boards for now...

Christiann, from your experience is there anything about your chair that you wish was different or improved. Do you see any limitations or restrictions that exist within the sport?

I really want to make sure I focus on the important aspects of this chair design, so we can see this sport progress even further!!

Interesting thread.

What are the most common or harmful injuries? Maybe you could include pioneering safety aspects.

Great point A La Carte. Saftey is definitely going to have to play an important role in this design. I know that there are many people who would choose not try this sport strictly due to it's dangerous perception.

Christiaan, if you have taken any hard hits while wheelchair skating I'd love to hear about them...

I also updated the blog with the flex-trispoke. Let me know what you all think.

Thanks,

Adam

Well as I said before, our biggest problem is keeping our speed once we do drop in. However, I think developing a sound suspension system is far more useful than changing the drive system.


I've sprained both my wrists, broken my thumb twice and dislocated my left knee...The worst was when I went in for X-Rays 3 months ago and found that one of my screws had slipped out and I had to have it re-screwed and cemented.








Now that's sick!!!... I'd totally rock that rim out at the park! Have you tried working the elastomer into the hub yet? If so, i'd imagine your going to want to go with a taller hub flange to support it...But thats damn cool looking rim!

Have either you or Christiaan thought about,, for the purpose of a little extra speed,, placing an additional pushrim, of a smaller diameter, on each wheel.

Similar to a racing chair's pushrim. It would only be used to add a bit of exceleration after initial push.

It would add weight and width, but it might also add a bit of control.
ed

Both of those wheels are something I would be proud to have on my chair,,, but I DO like that single spoke.

Edlee, thats a great idea. My only worry about the second pushrim is the difficultly of grabbing the pushrim after you've gained some speed. However, if the rim had some sort of free wheel mechanism that allowed it to stay still until pushed, that may make it easier.

Christiaan, sorry to hear about the screw coming loose. That sounds painful.

Thank you both for the kind words towards the wheels!

I updated the blog with a concept that would allow the rider to pump the suspension to create momentum while riding. Everyone can check it out here and let me know what they think. Sorry for another idea with handles in it haha.

Suspension concept

Loving the Flex Tri Spoke wheel!

Aratin that's awesome to hear, thank you!

Christiaan, I've got a couple more questions for you... Just wondering how often you adjust your seating position and how frequently you adjust your suspension settings. Just curious about how accessible I need to make these components. Also, wondering if you've had any trouble with that beautiful carbon fiber seat back getting messed up at all from crashing?

Hope your having an awesome weekend, and I hope to hear from you soon.

Thanks,

Adam

I wish wheelchair manufacturers listened to the SCI community the way you are.

That single spoke wheel looks SWEET!!! If you ever get them into production, let me know. I'd love to have those. But I'd take the split-3 spokes, because they're hot too.

The handrims you have shown are even better design than the Natural-Fit ones I have. When I bought mine, they were supposed to be "extra-grip" coated, but they weren't really "grippy" enough for me. I had the outside flat surface and outer curved area coated with Line-X. If the rims came precoated as you described, they would be much easier to use, and the protective anodized layer is great too. I don't do chair skating (Not enough balance or flexibility), but those rims would be a great help to lots of people, myself included. Particularly for those with less hand/finger function, or those (like me) who just can't seem to avoid hitting stuff and grinding the rims all the time.

If you ever decide to start a custom chair shop, I'll be plenty happy to be one of your test monkeys. You've got some cool ideas, and you are going about designing the chair in the right way-by asking what is needed. And you going into a skate park in a hospital style chair is totally ballsy man. That's the hardest kind of chair to use for anything, let alone for chair skating.

Take Care,

JAX

Hey Jax,

I'm so glad that you like the designs so far. It is a really great feeling to have such positive feedback. It's going to be a while until any full scale protoypes go into production, but as I said before, everyone here will be the first to get their hands on them. Your feedback is great and so incredibly helpful to me. I'm suprised there's not more companies looking into these communities.

Thank you so much, and please keep the feedback coming!

Adam

Hey guys,

The blog has just been updated with a design for the front casters and the frame. Please check it out and let me know what you all think. The designs are still concepts and can definitely be changed, so tell me anything you think. Good and bad.

Check them out here
Hope everyone is well and having a nice mother's day!

Thanks,

Adam

Adam,

The massive look of the tubes, while possibly heavier, makes this frame look even more impressive. Using those non-symetrical shapes for the tubes is als thought provoking,,,, how much does the shape of the material used, make the fabrication more difficult??

Would it be possible to get an exploded view of your casters,, or would you consider that proprietary info??? I'm just curious about what goes where.

I'm really looking forward to seeing your prototype chair,,,, just don't hurt yourself with it.
ed

I've love to give those front casters a roll. Frame looks pretty sharp, I'm ready to take one for a ride.

Adam, it looks AWESOME!!

Hey guys,

Really glad to hear you're all liking it so far!

Edlee, the new design of the tubing as well as the use of butting, allows for thinner wall thickness with extreme strength, so there should be no added weight. This involves using a custom extrusion, which does cost more than buying standard pre-made tubing, but would provide tremendous benefits. This is commonly done in bicycle design, however has yet to be applied to wheelchair design... I can also get you an exploded view of the caster in a couple days, as soon as I get a little more time.

Thanks for all the feedback... I will have some more stuff up there for you guys soon.

Adam

Hey Adam, I'm really liking your design ideas (wheels, frame, suspension), but I need to correct you on the above statement concerning the utilization of extrusion in wheelchair design. Marvel is currently using extrusion and butting in their wheelchair frame.

I have a Marvel and I really like it; however, I don't think it will appeal to everyone because it deviates from the wheelchair frame design that has been in place for many years..... the single walled tubular design. The Marvel doesn't have the "standard" tubes running beside the user's knees and lower legs. On the other hand, your design appears to use the best of both the old standby design and Marvel's current design. I think if your design continues to maintain the traditional look, while incorporating the extruded tubes, it will be appealing to most users.

Keep up the nice work and keep us posted!

(I'm still planning to upload some photos of my chair, but I've not been able to manage the time.)

Aratin, thanks for the link. The marvel wheelchair seems like a pretty incredible chair. I'm glad to see someone taking advantage of this technology. I can always appreciate a unique design such as that. Whenever you get some time I would love to see some pictures of yours.

I'm really glad your liking the design so far, later tonight I should have some more stuff for you to check out.

Hey everyone,

The design is moving along, and I will have some final renderings of it for you in a day or two! I just updated the blog with the final cushion design, which uses both foam and impact gel. I was able to get a large sample of the impact gel and do a little testing with it. I felt a signifcant difference both in the park and just rolling around on the sidewalks. It was tested using a solid seat attached to the frame. It was dificult to guage the improvments with the gel used on "hammock" style seating. As always, please let me know what you think of the design, your input is vital!

Cushion Design

Thanks,

Adam

Combining the seat and the cushion is interesting,,, you might consider making the lighter colored portions, interchangable, so as to change the shape,,,, both to improve stability, and protection from pressure or shear sores.

Maybe even air chambers that could be inflated once in the chair, to help hold the rider in place,,,, like the old pump up basketball shoes.

When is this design assignment due? I kinda like feeling a part of the process.
ed

Hey Edlee,

Sorry for the confusion, but the seat and the cushions will still be separate. There is a solid base attached directly to the frame that this cushion does rest upon. I really like the idea of having the cushion inserts interchangeable. That would allow the user to customize for comfort and for style. I looked into the air cushion, and I think they may be too fragile for this sort of application, you don't want something that could puncture being thrown around the skatepark. However if we used the interchangeable inserts, this could be an option for users more focused on comfort.

The project is officially due on May 28th, so I'm hustling at this point. My hope is, if this design keeps going the way it has been, I could build a prototype over the summer. And believe me Edlee, you are all a very big part of this process.

Thanks as always and keep the feedback coming!