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Thread: Carbon Fiber Racing Wheelchair

  1. #31
    Quote Originally Posted by Curt Leatherbee View Post
    Looks like a nice racing chair, myself I've never really had a interest in racing chairs because of the repetitive shoulder motion is not very healthy for the shoulder joints, that's why I ride a handcycle instead. I've got a pair of Corimas on the rear of my Freedom Ryder and a Zipp 404 on the front, I really like em. I gotta admit though, racing chairs can be fast, there was a guy in one in the recent Vermont City Marathon and I was just behind him for the first 5 miles or so and then he pulled away and took me on the hills and never looked back, I was surprised.
    As much fun as it is, I doubt that handcycling is risk-free to the rotator cuffs either.

  2. #32
    JeffAdams,

    I'm glad you weighed in with your comments. I've been wanting to share my opinion of the Icon wheelchairs for some time, but since it was none of my business if people wanted to ride around on something that looks like it should be bolted to the floor of an occupational therapy office, I politely refrained.

    The revolutionary Icon is by some measures impressive. It's likely the highest parts-count, most fastener intensive wheelchair offered to date.

    My wheelchairs do look very similar to many others. Tubular frames offer a range of benefits over more complex designs, especially in a circumstance where a wide variety of configurations may be required such as wheelchair frames. Ask some of the composite chair manufacturers out there what there tooling cost would be to produce a frame with a 1/2" shorter frame length than their current molds were designed for.

    "making something out of carbon that's exactly the same as a tubular metal construction isn't making the most of the material. With respect, copying a design and making it out of fancy material isn't really pushing the envelope very much" - well put. It isn't about making the most of the material, it's about making the most out of the product. Kind of like saying "let's use the same materials as everyone else, but we'll make ours look different and call it revolutionary". We'll include a slab of carbon laminated plywood though, so people think we're on the cutting edge.

    Why do some companies offer frame of exactly the same design in aluminum or titanium? Shouldn't they switch to a silly looking shape when they switch materials? Or do they know something that you may have missed. The design is sound, but gains can still be made in the base material. Modern metal frame wheelchairs offer very adequate strength and durability. My goal was not to build a "stronger wheelchair", but rather a lighter wheelchair that didn't sacrifice strength and durability.

    But I do absolutely agree that noone should offer a wheelchair for sale until it has been thoroughly tested and certified to be safe. Should Black Alloy Sportschairs begin offering wheelchairs for sale, rest assured they will have passed all applicable fatigue tests. And they won't require a bottle or two of threadlocker to do it.

  3. #33
    Senior Member DaleB's Avatar
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    Quote Originally Posted by JeffAdams View Post
    Sorry then - it looks just like an Invacare A4 or Eliminator, not a Marvel.

    Same comment. If it's not tested, please don't sell it.

    Yup.
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  4. #34
    Senior Member DaleB's Avatar
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    Should Black Alloy Sportschairs begin offering wheelchairs for sale, ...

    "Should"?!?!

    Don't tell me you're just showing off.

    Sell them, yes, test them and sell them. Indeed!

    Materials evolution is fine by me. I've yet to be let down by conventional wheelchair design, in any significant way.

    Design changes, for their own sake, aren't innovative, IMO.

    Engineers can be terrific at solving problems that don't exist, and putting too high a premium on the "technical sweetness" of a design, or process, over a more holistic view of the end user experience.

    Sell them, please, if they work well!
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  5. #35
    I guess it looks just like an A4. Except for all the differences.

    One subtle difference might be the Ti A4 frame stripped bare is 6lb-8oz and the Composite chair as photographed is 10lb-8oz. A better number might be the 3lb-8oz bare weight of the composite frame.

    The mechanical properties of the individual structural tubes and connections, both individually and as an assembly, are designed to deliver very similar performance to that of a fully welded frame from commonly used Ti6Al4V or Ti3Al2.5V alloy.

  6. #36
    Quote Originally Posted by stephen212 View Post
    As much fun as it is, I doubt that handcycling is risk-free to the rotator cuffs either.
    the circular movement is very good for our shoulders actually. I have a great letter I use with marathon officials pointing this out from a leading sci doc I work with.
    Bike-on.com rep
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  7. #37
    Send me a sample of your everyday chair, I'll put it up on our in-house RESNA rollers and let you know how it goes.

    I'm particularly sensitive to chairs (particularly racing chairs) being built without any testing, because one of my training partners, Gavin Foulsham had a nearly life-ending accident because the manufacturer he was racing for played the weight game without any testing. Gavin snapped his main frame on a downhill going over 40mph, and is lucky to still be with us.

    Don't get me wrong - it's a nice chair, and I'm sure it works for you, but the reason I'm frustrated and acting so pissy is that this often happens - some guy with a shop in his garage builds a chair that would never pass the industry safety standards, or get anywhere close to an acceptable price for a consumer.

    Then everyone gets excited about it, and manufacturers who do test their products and meet the safety standards get held to an artificial standard for weight.

    On the topic of artificial weights and another pet peeve of mine, if the composite chair that you're referring to is the photo of your everyday that DaleB posted, there's no way it's 10lb all in.

    The back wheels are 24 steel spokes with standard pushrings, and it looks like you migrated parts over from your A4 - you have a metal footplate, brakes, and a solid back. Those wheels weigh at least 7 pounds on their own (even a set of Topolino carbons weigh 6) - then add the weight of the axles to that total. I would bet that the wheels and accessories weigh close to 10 pounds on their own.

    I'm sure the chair is light, and you might be able to get it down to the low double digits, but I have a hard time believing that it's 10 lbs as it sits in that photo - which is the peeve I have - manufacturers and others who make claims about weights in marketing materials that stretch the truth to the breaking point.

  8. #38
    Senior Member flying's Avatar
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    Quote Originally Posted by fuentejps View Post
    the circular movement is very good for our shoulders actually. I have a great letter I use with marathon officials pointing this out from a leading sci doc I work with.
    I think you are right about the shoulders and hand cycling. Riding makes my shoulders feel pretty good but pushing my chair over ruff ground hurts, loading my chair into my truck is not so hot ether.
    T12L1 Incomplete Still here This is the place to be 58 years old

  9. #39
    Quote Originally Posted by flying View Post
    I think you are right about the shoulders and hand cycling. Riding makes my shoulders feel pretty good but pushing my chair over ruff ground hurts, loading my chair into my truck is not so hot ether.
    In a more perfect world where there were not SCIs we would be riding regular bicycles as our legs are obviously better adapted to this activity. I'm not suggesting in anyway that shoulder injury is an inevitable result from handcycling, but it's a stressful repetitive motion activity, which places all the joints of the hands, arms, and shoulders at some risk.

    My original point was that while handcycling poses less chance of injury to the shoulders than wheelchair racing, it's still not risk free.
    Academic research exploring the risks and how best to prevent them is in its infancy, but here's a sample study.

    Obviously some people by virtue of personal anatomy, genetics, nutrition, and carefully selected equipment and training regimens are less impacted or not impacted at all. And the benefits of handcycling -- cardiovascular conditioning, strength building, social involvement -- are huge pluses.

  10. #40
    Quote Originally Posted by flying View Post
    I think you are right about the shoulders and hand cycling. Riding makes my shoulders feel pretty good but pushing my chair over ruff ground hurts, loading my chair into my truck is not so hot ether.
    ya, nothing makes my shoulder feel better than getting out and cranking. lubes the joints.
    Bike-on.com rep
    John@bike-on.com
    c4/5 inc funtioning c6. 28 yrs post.
    sponsored handcycle racer

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