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Thread: Icon Wheelchairs are now available for sale.

  1. #41
    Quote Originally Posted by DaleB View Post
    A single leaf isn't a leaf spring, technically. The stack and the ratio of size between leaves creates a decelerating effect. Not a good one, mind you, but for 100 year old technology it's not bad.
    point taken. you know what I mean though.

    Quote Originally Posted by totoL1 View Post
    I don`t have springs, and 100 year ago CF wasn`t exist, i remember you that you are not in a Hammer, so your teory of bounce is just a teory that is not really important for a fucking wheelchair.

    Anyway looks very clear that you and scott are going to work for Jeff, so you will have to speak about how fantastic is the Icon.

  2. #42
    Quote Originally Posted by DaleB View Post
    Things that add bounce don't add suspension. Suspension is deceleration of force, and it requires a medium to transfer the force into heat through. Springs just bounce. CF strips just bounce. Froglegs elastomers just bounce. There is no deceleration occurring, and this has been proven in a research study. Even the XTR, while better, pales in comparison as it's shock was/is non-adjustable. You need preload, compression and rebound dampening in order to setup suspension to actually work at low velocity.
    This is a good, technical, engineering explanation of suspension versus bounce. As a Licensed Professional Engineer, I appreciate it. Thanks.

    Quote Originally Posted by DaleB View Post
    Excellent paper! I saved it for future reference.
    Last edited by chasmengr; 07-23-2011 at 11:44 AM.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
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  3. #43
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    Quote Originally Posted by totoL1 View Post
    I don`t have springs, and 100 year ago CF wasn`t exist, i remember you that you are not in a Hammer, so your teory of bounce is just a teory that is not really important for a fucking wheelchair.

    Anyway looks very clear that you and scott are going to work for Jeff, so you will have to speak about how fantastic is the Icon.
    Wow, you need to take a deep breath. True, CF isn't 100 years old, but the physics of a leaf spring, which is what Scott and Dale are talking about certainly is. Notice that I said the physics of the CF spring, not theory. Drop a 100 Gram weight on a strip of CF and watch what happens to it - it will bounce. That's physics, not theory.

    How is you working for Oracing any different? I've seen no disrespect of you for touting their products. You need to give others the same treatment you have gotten.
    Don - Grad Student Emeritus
    T3 ASIA A 26 years post injury

  4. #44
    Quote Originally Posted by Donno View Post
    Wow, you need to take a deep breath. True, CF isn't 100 years old, but the physics of a leaf spring, which is what Scott and Dale are talking about certainly is. Notice that I said the physics of the CF spring, not theory. Drop a 100 Gram weight on a strip of CF and watch what happens to it - it will bounce. That's physics, not theory.

    How is you working for Oracing any different? I've seen no disrespect of you for touting their products. You need to give others the same treatment you have gotten.
    The Donno Lama has spoken.

  5. #45
    I probably should have used the term "trampoline" instead of "spring."

  6. #46
    Dale, your suspension discussion got me thinking. . . that a titanium cantilevered frame may actually have some true integral suspension (albeit minor) because of the flexible, shock-absorbing properties of the metal. Comments?
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

  7. #47
    Senior Member sowseng's Avatar
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    Quote Originally Posted by chasmengr View Post
    Dale, your suspension discussion got me thinking. . . that a titanium cantilevered frame may actually have some true integral suspension (albeit minor) because of the flexible, shock-absorbing properties of the metal. Comments?
    I tried TR, may be the frame was too rigid that I feel all the impact.

    Where else, for open titanium frame, not so much impact. As I observe, may be because the frame on front seat do flex, and do away with the impact.
    Life is meaningles, though you create the purpose.

  8. #48
    Senior Member DaleB's Avatar
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    Quote Originally Posted by totoL1 View Post
    I don`t have springs, and 100 year ago CF wasn`t exist, i remember you that you are not in a Hammer, so your teory of bounce is just a teory that is not really important for a fucking wheelchair.

    Anyway looks very clear that you and scott are going to work for Jeff, so you will have to speak about how fantastic is the Icon.

    I was speaking of leaf springs, not CF.

    A couple of points:

    First, I'm not involved with anyone's project, period. I paid retail for my Marvel, too, on purpose. I speak from a clear conscience. I have paid for every piece of equipment I own.

    You are the one with financial interests in the products you "review".
    You are the one with an external link to a site marketing a product you sell.
    You are the one who was given a set of wheels to 'review'.
    The list goes on.

    You need to check yourself, amigo. I have offered nothing offensive and only factual information and honest opinion.

    Sorry to have offended you, but your reaction speaks volumes. You are the one with interests to defend, obviously.
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  9. #49
    Senior Member DaleB's Avatar
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    Quote Originally Posted by totoL1 View Post
    ok, so speak about thing that you have tried, i could clean my arse with the teory.
    I guess you didn't read the paper I linked. Print it out and try wiping your arse with that. Read it first, though.
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  10. #50
    @toto - One of the points you're making is something that both Christian and I value a lot - there are a lot of people who have done a lot of "trial and error" work to try new things - you're one of them, and there are many others.

    To be clear, -scott- is doing work for us, DaleB is not, although he has given us advice - we canvassed a lot of the people who bought our previous chair for their advice, and he was one of them.

    Both of them are right though - the CF seat that you developed are springs. Just because of the language barrier, I want to make sure that you understand that this is not an insult. Springs are fine sometimes, and seem like the most appropriate mechanical device for the problem you encountered.

    Your design parameters were very different from ours - you wanted a minimalist, light, custom configured way to keep your seat performing consistently (not loosening off like the straps did before Oracing corrected the problem) - you got a bit of spring return from the carbon fiber (which was the exact right material to use), which seemed like a nice additional benefit, and a bunch of other people took a look at it and thought that it would work for them too.

    But then you ran into a problem - the people who were asking for your help weren't the same size and weight as you, so you did the right thing - you told them that the solution worked for you, but that you had no idea how it would work for them - that they might need stiffer or thicker strips or different cutouts to get the spring effect they wanted. You warned them that they might spend money to buy the carbon and have it made, and that at the end of the day, it might work, or it might not.

    That's the difference between trial and error (again, which can be very valuable in research and development) and engineering. It's the difference between just having a theory and being able to prove it to a very high level of validation with a scientific test. We know exactly what's going to happen to our chair, and the person in it, because we've spent months doing tests.

    It's also the difference between custom and adjustable - custom (or semi-adjustable) is fine if you "nail it" (assuming that you in fact do know "exactly" what you need in terms of geometry), but if anything changes after that, you're looking at a rebuild - if you grow or shrink or run into a situation where you need to change your backrest or cushion - you're looking at a rebuild, or living with a change in geometry.

    Sometimes the only way to find out if something works is to build it (racing chairs and handcrank cycles often fall into this category), and people like Peterson and Schulte have been doing awesome design and fabrication for years on those products, but other times it's good to have science back things up.

    The Icon won't be for everyone - you clearly think that it's not for you, which is fine, and I appreciate you wishing us well. We also wish other chair companies well, because they deliver products to people who have other and specific requirements - I'm personally a really big fan of Oracing products, I'm actually trying to get a kneeler handcrank cycle from them (if you can put in a good word for me, I'd appreciate it).

    We're never going to try to get into the custom market - it's just not what we do, but there is a clear need for well made custom chairs and sports equipment, and I have a huge respect for the people who have done so much work to get people the equipment they need - Jim Knaub, Jim Martenson, Chris Peterson, Paul Schulte, Alan Ludovici, Marty Ball, Marilyn Hamilton...there's a huge list of people - some of them started off in their garages (again, not an insult - so did Apple).

    Having said that, the time for building things in garages is over, and good engineering is not "just theory" - it's science, and with all due respect, Toto, it absolutely is important for "fucking wheelchairs".

    I think way more important than it is for bikes or cars or inline skates and hockey sticks (all of which have gotten more engineering than wheelchairs historically).

    One of the things about Icon is that it's run by a couple of guys in wheelchairs, and what we want most of all is to see people in equipment that is best for them, so like last time, we'll sometimes tell people to go buy something else. We feel an enormous mantle of responsibility to not "hard sell" to the community that we're a part of, or push anyone into our equipment if there's something out there that will do them more good.

    One of the big errors that we want to avoid is trying to be all things for all people - we set pretty strict design parameters for ourselves this time around to try to keep everything as simple as possible for a chair that does so much.

    So this was a long reply to say something very simple - we're proud of the work we've done, we hope we're taking things to a new level, and also hope that we encourage and inspire other companies to do the same.

    We're not looking to pick fights nor do we need to "be right" - our solutions will work for some, but not all, and we're ok with that. We got to where we are by listening to people who use chairs, and know that we need to keep doing that if we want to be successful - and it's not just listening to the people who applaud, but maybe more important to listen to those who don't.
    Last edited by JeffAdams; 07-23-2011 at 12:54 PM.

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