Page 2 of 5 FirstFirst 12345 LastLast
Results 11 to 20 of 44

Thread: 25vs24 wheel-size comparison (aka too much free time)

  1. #11
    Quote Originally Posted by ala View Post
    . . . Thanks.
    You're welcome, and Thank you.

    I suspect others may be thinking "Oh, please don't encourage him."
    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>

  2. #12
    Quote Originally Posted by ~Lin View Post
    That's what I was wondering for myself after reading brianms post. I started a thread about it, I wondered if going up to 25 wheels would increase my pushing efficiency since I cant further lower my rsh. The response I got for me was no, maybe I need to go back and look over things again!
    Lin, if you provide pertinent measurements, I'll be glad to run the math for you.
    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

    Major OOPS

    Accurate dimensioning is critical!!!!

    This morning, my wife measured me, and the difference is dramatic!! a complete reversal!! Sketch shown below. Apparently I've had my RSH too low all this time.
    Attachment 47153
    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>

  4. #14
    Quote Originally Posted by chasmengr View Post
    ... empirically I already observed that I wished for a tighter elbow angle....
    Did you not go from 5 degrees less to 4 degrees less? My eyes are playing tricks with me. Where is the reversal?
    Last edited by nonoise; 10-25-2012 at 01:49 PM. Reason: I must have misunderstood.
    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.

  5. #15
    Quote Originally Posted by nonoise View Post
    Did you not go from 5 degrees less to 4 degrees less? My eyes are playing tricks with me. Where is the reversal?

    The reversal is empirically I was wrong - I need to trust math more than my empirical senses. My self measurements yielded a current elbow angle of 131DEG; my wife's measurements (much more accurate) yielded a current angle of 92DEG. The target elbow-angle range is 100-130DEG. So instead of needing a lower RSH, I actually need a higher RSH.

    Grommet said it: "Some one once told me that you can get used to something unnatural until it feels natural and I think that happens a lot with chairs. Something isn't right but we figure that's how it is."
    Last edited by chasmengr; 10-25-2012 at 02:08 PM.
    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>

  6. #16
    Senior Member elarson's Avatar
    Join Date
    Mar 2012
    Location
    The Netherlands
    Posts
    2,222
    Very interesting stuff Chas.

    I've only got as far as figuring out RSH based on Arm Length, Shoulder Height and the Seat Surface to Axel Height (I think). Does this mean that the elbow angle and COG also affects the RSH?

    Quote Originally Posted by chasmengr View Post
    Accurate dimensioning is critical!!!!
    Partner of an incredible stroke survivor. Limitations: hemiparesis and neglect (functional paralysis and complete lack of awareness on one side). Equipment: TiLite ZRA 2 and 2GX, Spinergy ZX-1, RioMobility Firefly. Knowledge: relative newbie for high-level equipment (2012), but willing to try to help others who are new with similar limitations (definitely not a guru, but inquisitive).

  7. #17
    Quote Originally Posted by elarson View Post
    Very interesting stuff Chas.

    I've only got as far as figuring out RSH based on Arm Length, Shoulder Height and the Seat Surface to Axel Height (I think). Does this mean that the elbow angle and COG also affects the RSH?
    Determining RSH from arm length (aka fingertip-touching-axle rule) is the easy, aproximate way. Actual research shows pushing efficiency is better determined from the elbow angle, but (as can be seen from this thread) the elbow-angle method is much more complex.

    What I am doing is trying to use the complex method (including shoulder-to-axle relative positions, etc), for which measurement accuracy is super critical. I'm working up a spreadsheet, which I'll post when it's further along.
    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>

  8. #18
    Senior Member
    Join Date
    Aug 2012
    Location
    United States
    Posts
    382

    One Word...

    ICON :P

    E

    PS I am teaching Law of Cosines and Sines right now to my Trig students. Do you mind if I "word problem" your situation?
    There is no such thing as a stupid question but there sure are a lot of inquisitive idiots. -modified from despair.com

  9. #19
    Quote Originally Posted by Essie View Post
    ICON :P

    E

    PS I am teaching Law of Cosines and Sines right now to my Trig students. Do you mind if I "word problem" your situation?
    I'd be honored It's always wonderful when students can experience real-world uses for what they're learning.
    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>

  10. #20
    that paper's too complicated for my brain, lol.

    so does that mean the 88 degree is better than 92 in pushing efficiency?

Similar Threads

  1. Can I use a bigger tube for my wheel size?
    By BrandonBynum in forum Equipment
    Replies: 5
    Last Post: 10-13-2012, 06:55 PM
  2. Shower Chair wheel size
    By ChesBay in forum Equipment
    Replies: 3
    Last Post: 07-26-2011, 09:43 PM
  3. Wheel size - why choose 24, 25, or 26?
    By chasmengr in forum Equipment
    Replies: 18
    Last Post: 03-02-2011, 02:23 PM
  4. Wheel size, does it matter?
    By november in forum Equipment
    Replies: 9
    Last Post: 06-22-2008, 07:43 AM
  5. Your caster wheel size?
    By joshstevens7 in forum Equipment
    Replies: 46
    Last Post: 03-16-2006, 09:30 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •