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It's a relatively small market so the up front capital and ongoing labor costs are probably pretty restrictive. Those parts are more expensive than you realize

by rtkwe 2y ago

It's a relatively small market so the up front capital and ongoing labor costs are probably pretty restrictive. Those parts are more expensive than you realize though with the wheels being the most expensive part if I had to wager, they're critical, specialized, and need to stand up to a lot of abuse.

hinkley 2y ago
I toured the Trek factory when they still made them in the US. They'd already drunk from the font of Goldratt wrt to Just in Time, but they would set up each day pretty much to make one model of bicycle for the whole day. Parts, tooling, paint booth, everything. The only thing that changed was sizes, and a model of bike tends to have the same geometries across all sizes. 78º angle here, 99º angle there. That may not be optimal for the rider but it's how you keep prices down and keep product lines from getting confusing. If that's true of wheelchairs, you can get some economies of scale even if sizes vary. If it's not, then maybe that's one of the things we should tackle.
- rtkwe 2y ago
  The bend angle of the tube that forms the seat support down to the legs seems like one of their major adjustment points for comfort and efficiency so I don't think you could have a similar setup. These are essentially semi-custom not a simple size based product like a bike. The extra adjustments are important because the users are in them many more hours a day so small problems can cause long term issues. Their configurator has a very good model of what the chair will look like and you can see just how many knobs you can tweak and how that requires changing the core layout of the frame in a way that makes the kind of sizing system just not feasible. Scroll down on the Frame page to get to the fit sliders. https://notawheelchair.com/pages/configurator https://notawheelchair.com/pages/configurator edit: Did the math and there's something like 25k different configurations they're selling before accounting for paint colors, just in the frame measurements. Granted, that's not accounting for the improbability or incompatibility of some parameter sets but that's still going to be a couple thousand different configs to build and stock. It doesn't work like a bike.
  - hinkley 2y ago
    On a bike you have a little bit of flexibility due to the way the seat post works. Both in how the seat attaches and adding curves to the post, particularly for triathletes who like to favor their hamstrings over their quads, and sit considerably farther forward than any 'normal' cyclist would. I know I've seen wheelchairs where the back was a tube that went into a tube. If you put the curve in the replaceable part you get more adjustment but less support. Generally the tolerances on bikes are very tight and medical equipment seems to be all over the place.
    - rtkwe 2y ago
      They've done a lot of work it looks like to put in user level adjustments everywhere they can but to tweak the parameters on the frame page I don't see a great way to replace that. The curve it's tweaking is setting the angle between the legs and the seat already.
      - hinkley 2y ago
        Yeah I went through the build your own UI after your last reply and it looks like a pretty complex bracket there for adjusting the angle of the seat back. From the look of things it's an adjustment versus another bracket. It looks expensive, but I suspect that not being able to change your mind after you order is awful. Anything from muscle gain to tweaking your back probably makes you want to adjust your seat a bit. So maybe it's worth however many dollars that takes out of the $1k budget to be preserved in the design.
        rtkwe 2y ago
        The seat back and center of gravity position both look fairly adjustable. The main fixed quantities seem like they're all on the frame page; seat heigh front and back, frame depth (back of seat to knees), front angle, and frame taper. The rest of the options seem pretty adjustable looking at the frame there's a lot of mounting holes to change all the other measurements.

by rtkwe 2y ago

hinkley 2y ago

I toured the Trek factory when they still made them in the US. They'd already drunk from the font of Goldratt wrt to Just in Time, but they would set up each day pretty much to make one model of bicycle for the whole day. Parts, tooling, paint booth, everything. The only thing that changed was sizes, and a model of bike tends to have the same geometries across all sizes. 78º angle here, 99º angle there. That may not be optimal for the rider but it's how you keep prices down and keep product lines from getting confusing. If that's true of wheelchairs, you can get some economies of scale even if sizes vary. If it's not, then maybe that's one of the things we should tackle.

rtkwe 2y ago
The bend angle of the tube that forms the seat support down to the legs seems like one of their major adjustment points for comfort and efficiency so I don't think you could have a similar setup. These are essentially semi-custom not a simple size based product like a bike. The extra adjustments are important because the users are in them many more hours a day so small problems can cause long term issues. Their configurator has a very good model of what the chair will look like and you can see just how many knobs you can tweak and how that requires changing the core layout of the frame in a way that makes the kind of sizing system just not feasible. Scroll down on the Frame page to get to the fit sliders. https://notawheelchair.com/pages/configurator https://notawheelchair.com/pages/configurator edit: Did the math and there's something like 25k different configurations they're selling before accounting for paint colors, just in the frame measurements. Granted, that's not accounting for the improbability or incompatibility of some parameter sets but that's still going to be a couple thousand different configs to build and stock. It doesn't work like a bike.
- hinkley 2y ago
  On a bike you have a little bit of flexibility due to the way the seat post works. Both in how the seat attaches and adding curves to the post, particularly for triathletes who like to favor their hamstrings over their quads, and sit considerably farther forward than any 'normal' cyclist would. I know I've seen wheelchairs where the back was a tube that went into a tube. If you put the curve in the replaceable part you get more adjustment but less support. Generally the tolerances on bikes are very tight and medical equipment seems to be all over the place.
  - rtkwe 2y ago
    They've done a lot of work it looks like to put in user level adjustments everywhere they can but to tweak the parameters on the frame page I don't see a great way to replace that. The curve it's tweaking is setting the angle between the legs and the seat already.
    - hinkley 2y ago
      Yeah I went through the build your own UI after your last reply and it looks like a pretty complex bracket there for adjusting the angle of the seat back. From the look of things it's an adjustment versus another bracket. It looks expensive, but I suspect that not being able to change your mind after you order is awful. Anything from muscle gain to tweaking your back probably makes you want to adjust your seat a bit. So maybe it's worth however many dollars that takes out of the $1k budget to be preserved in the design.
      - rtkwe 2y ago
        The seat back and center of gravity position both look fairly adjustable. The main fixed quantities seem like they're all on the frame page; seat heigh front and back, frame depth (back of seat to knees), front angle, and frame taper. The rest of the options seem pretty adjustable looking at the frame there's a lot of mounting holes to change all the other measurements.