View Poll Results: For yor manual rigid frame chair, does your fork assembly flutter at 15 mph?

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  • yes, but not so bad that it is unsafe

    1 2.70%
  • yes, and it is bad enough to be unsafe

    7 18.92%
  • no

    29 78.38%
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Thread: Danger: TiLite ZR2 front wheel assembly flutters and locks up

  1. #11
    Senior Member Axle's Avatar
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    Besides, 15 mph is not 'speeding'. A person runs faster than that. Sorry Nancy. Your response to slow down would be reasonable if I were going twice that speed. But if a grandmother could run faster than that, I think my expectation is reasonable.
    Last edited by Axle; 01-20-2013 at 07:59 PM.

  2. #12
    Quote Originally Posted by tooley View Post
    I realize that sign near the end is 40kph, that is a warning for the turn. He is definitely exceeding that speed as he approaches it. Between the 3 and 4 minute mark of the video there are portions where (IMO) he is definitely getting close to 40mph.

    I don't think the OP is asking too much of his new chair.
    Oh, a plane, I couldn't see it

    You're right, the sign is a curve warning, not a speed limit.

    If the OP is not asking too much, then my chair has too much flutter, too. I had 6" TiLite softrolls, and they would flutter coasting down an ADA ramp all lubed, squared and with tightened forks. I switched to FLAHSR, and they don't flutter on ramps, but I can still get them to flutter coasting down a steep hill not even approaching 15 mph. Maybe I'm setting my expectations too low.
    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>

  3. #13
    Rarely will a manual wheelchair attain anything close to 15 MPH unless it is rolling downhill.

    I use 4 x 1.5 FrogLegs Aluminum Hub soft roll casters on regular bearing forks and have never experienced caster flutter. I can let my chair coast freely down the full length of a parking garage ramp and experience no flutter at all when I reach the bottom. I don't know what my terminal velocity is, but it takes me 100-150 feet to stop.

    Now that I think about it, I don't remember seeing caster flutter on any TiLite rigid frame.

    My guess is that the source of your problem is the very basic 4x.75" plastic wheel/poly tire. That is a very narrow, low end caster that is made out of a relatively soft material. It is installed on a fork that can accommodate casters that are up to twice the width. Bearings that are seated in a soft plastic hub will not have the same precise alignment as bearings seated in an aluminum hub. Not only are the tolerances much looser, the caster axle is relatively wide.

    The only other thing I can think of would be a floating caster because of uneven tension in the footrest.
    Last edited by SCI_OTR; 01-20-2013 at 08:15 PM.


  4. #14
    Senior Member Axle's Avatar
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    Quote Originally Posted by chasmengr View Post
    IMO 15 mph is very fast for a wheel chair. I would expect most casters greater than 3" diameter to flutter at that speed. For being pulled outside by a dog, I'd get a FreeWheel.

    Thanks for the lead. I will consider the FreeWheel. But I should say that my expectation for my new TiLite to be able to travel 15 mph is reasonable. Even TiLite says it is a reasonable expectation.

  5. #15
    Senior Member Axle's Avatar
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    Quote Originally Posted by chasmengr View Post
    Oh, a plane, I couldn't see it

    You're right, the sign is a curve warning, not a speed limit.

    If the OP is not asking too much, then my chair has too much flutter, too. I had 6" TiLite softrolls, and they would flutter coasting down an ADA ramp all lubed, squared and with tightened forks. I switched to FLAHSR, and they don't flutter on ramps, but I can still get them to flutter coasting down a steep hill not even approaching 15 mph. Maybe I'm setting my expectations too low.
    Your expectations are certainly too low. The purpose of a wheelchair is not only access but also mobility. If you can run that fast your chair should go that fast. I can see if you bought a budget chair you may be dreaming. But remember we are talking state of the art chair.

  6. #16
    FWIW Wikipedia says that racing wheelchairs can exceed 30 kph (about 20 mph), and they use large-diameter front wheels.
    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. #17
    Senior Member Axle's Avatar
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    Quote Originally Posted by SCI_OTR View Post
    Rarely will a manual wheelchair attain anything close to 15 MPH unless it is rolling downhill.

    I use 4 x 1.5 FrogLegs Aluminum Hub soft roll casters on regular bearing forks and have never experienced caster flutter. I can let my chair coast freely down the full length of a parking garage ramp and experience no flutter at all when I reach the bottom. I don't know what my terminal velocity is, but it takes me 100-150 feet to stop.

    Now that I think about it, I don't remember seeing caster flutter on any TiLite rigid frame.

    My guess is that the source of your problem is the very basic 4x.75" plastic wheel/poly tire. A narrow, low end, caster made out of a relatively soft material on a fork that can accommodate casters that are up to twice the width. Bearings that are seated in a soft plastic hub will not have the same precise alignment as bearings seated in an aluminum hub because. Not only are the tolerances much looser because of the soft hub the caster axle is relatively wide.

    The only other thing I can think of would be a floating caster because of uneven tension in the footrest.
    Thanks. Good input. I can see how an uneven footrest could be bending the frame. But it would have to be way off. Otherwise having to get the footrest perfectly level means that the chair is not manufactured well enough to accommodate tolerances.

    Changing the wheels is a more realistic solution. But then why didn't TiLite recommend that?

  8. #18
    Senior Member Axle's Avatar
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    I have to say that I did not clock the speed to be 15 mph. I am guessing that is the speed that my dog pulls me because she goes at the speed of a sprint. I also repeated the test with someone pushing me and they weren't sprinting. They were jogging. I think a human jogs at far less than 15 mph, maybe closer to 10 mph. Whatever that number is I know that my expectation is reasonable and TiLite did not disagree. I should add that the chair vibrates at any speed greater than walking speed (3 mph).

    I wonder if moving the the rear axle forward would remove enough force on the front casters to stop the flutter.
    Last edited by Axle; 01-20-2013 at 08:42 PM.

  9. #19
    When you put it that way...running speed, maybe so. Curiosity here...how do you brake at high speed? Do you have hub brakes that actually brake for you?. Downhills I tend to slow myself down as I go down... I have to admit I am kind of a chicken, and new to the active chair user thing. I'm amazed to find out chairs can go 40mph....that's friggin incredible!!
    Tourette's Syndrome - motor tics of the legs, feet and back, which can make it difficult or impossible to walk

  10. #20
    Wobble seems to be a continuing problem. I'll offer up my opinion.

    My folding chair casters wobbled with 5 inch composites. I switched back to the aluminum hubs with 7" wheels and have not had a problem since. So I'm inclined to believe it has more to do with perfect bearing alignment than other factors. You can tighten the wheels on the axles and think all is well, but what I notice is that the bolt that is used for an axle is a sloppy fit. It's too small of a diameter. The spacer helps, but it is not perfect, the bearings need to be seated. So if the two bearings are not exactly parallel, you never know it until the wheel wobbles.
    I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

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