Cushion Pros and Cons

I found this informative breakdown of the pros and cons of different materials used for seat cushions. This should be helpful when it comes down to designing the seat. Check it out here.

Flex Tri Spoke

With a unique woven spoke design, and an elastomer coating around the center hub (thanks Christiaan), this carbon fiber wheel is designed to help absorb the constant impacts of wheelchair skating.

Gaining Speed

Through my experiences and watching others use their chairs in the skatepark, the greatest limitation of the sport has always seemed to be the ability to generate and maintain speed. The idea here is a very simple gearing mechanism that would fit between the rear wheel and the frame. The rear wheels can be controlled as usual by the pushrim, but after you drop in and gain some speed, the rpm based clutch will engage the free wheel gear. Then using the handles, users can continue to build speed by spinning the the gears. The gear ratio will allow for more aggressive speeds that would be impossible to reach by just pushing the wheels. At anytime the user would be able to grab the pushrims to control the chair as usual. The mechanism itself would be no more complicated than that on a bmx bike, and would allow users to customize gear ratios for specific tricks and terrain.

The actual placement and form of this concept has yet to be realized, but will be designed for limited interference with the user.

Sorry for the crude illustrator sketch!!!

Apparelyzed.com

Due to the specificity of my project, finding users to talk to has been much more difficult then with previous projects. I was lucky to find an amazing group of people on the forums of apparelyzed.com
Throughout this process I have been able to receive constant feedback, from user's with first hand experience. Without they're help this project would not be possible.

Check out the thread here.

Wheel and Pushrim

While testing the chair, I immediately noticed problems with the design of the pushrim. As I rolled, I would continuously get my fingers caught in the attachment rods. The stainless steel material was also slippery when my hands were sweaty, giving me less control over the chair.

The redesigned pushrim is a more ergonomic form that eliminates any connection gaps that might trap fingers. It would be extruded in a rubberized silicon which would allow for better grip. An anodized steel "crash guard" is inserted on the outside to protect the rim from the abuse of the park.

I also modeled the single spoke wheel design for this rendering. If created in carbon fiber, the wheel could be tuned to for the right rigidity and strength to make the design possible. There would have to be some counterweighting done throughout the rim to even out the weight distribution, but the design would result in a lightweight, unique aesthetic, that allowed for easy access to under the chair.

Wheel Design (sketches)

I started with a few sketches of the wheelchair wheels just to get the ball rolling. These three were the ones that seemed to stand out.

Weight Distribution

After trying to drop in on the quarterpipe, I began to rethink the weight distribution of the wheelchair setup. Riding the park often requires that you quickly pull into a wheelie position, however with current setups it is not easy to do this while moving. By pushing the rear wheel forward on the frame, the users weight would be further back allowing them to easily lean back into a wheelie positon. It seems this would also make it easier to ride the ramps as your weight would stay further back over the rear wheel. I need to look more into the exact details, but this is just my educated guess. Let me know what you think.

Return For More Testing

After some more thought and a couple modifications to the old wheelchair, I returned to the skatepark for some more testing. I fixed the front casters to see what type of handling loss there would be if the front two wheels weren't free. I was thinking about redesigning the footrest and front casters to work more like a skateboard truck. This would allow for better straightline stability forwards and especially backwards, and also provide an area to grind with. But, with the wheels the size they were it made it very difficult to turn with them fixed. It seems like that idea isn't going to be worth the sacrifices it would require.


I then spent some time looking at how to drop in on a little 3 foot quarterpipe. To start it was very difficult to position the chair with the front wheels over the coping. It requires the user to approach in a wheelie position all the way up to the edge. For an inexperienced user this is very difficult. When I got into position and leaned in to drop in, my weight seemed way too far to the front, and as I dropped I quickly fell forward. Though with experience I'm sure this could be corrected, the chair's weight distribution seemed like it could be better optimized for skatepark usage. As other users tried to drop in they experienced the same issues.

Contextual Research

I was able to borrow a wheelchair and jump into some first hand contextual research, trying it out on the ramps of a skatepark. Turns out it's just as hard as you would think it might be... Though I left with a few bruises, I also gained some valuable insight, and some great design opportunities.