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24 to 25" rear wheels make chair tippier?

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    #31
    Originally posted by rlmtrhmiles View Post
    rollin..move your head I and guarantee your COG will change.
    lol, i gotcha.

    height and width are not a problem. i only got 2 degree camber and my fsh is only 18.5. i had 20" on my old chair and there were only minimal things my knees would hit. guess the transferring is my only worry then.

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      #32
      SuperSi...try sit far enough, near edge of your seat and with you body and arms in correct position, I bet you can tip your chair over far faster than your body can recover from that COG change. I've done it 2X on new chair in less than 1 week. First time it happenedd I did not know what the hell happened. 2nd time was not too long after 1st and finally realized what going on. Your COG is a measurment based on your position to the center of the Earth.

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        #33
        For some reason most wheelchair manufacturers do the measurement wrong. The cog for wheelchairs is actually how far forward the axle is from the backrest. So it's not truly your 'centre of gravity'. And this is irrelevant to this discussion. Rollin has stated he wants a 2" cog, which will be the same regardless of what size wheels he specs.

        Miles, we're not talking about tippyness forward, when people talk about tippyness it's generally backwards. And still, having larger rear wheels on a new chair designed for them will not change how tippy the chair is forward or back. It will only effect your pushing geometry and how high you have to lift your butt to transfer.

        edit: I think I understand what's happening with you.. so let me just see if I understand you right, when you sit at the front edge of your seat, the chair is tipping forward? If so thats because your weight is too close to where the casters are. We were taught in rehab to park with the casters facing forward to give you more stability. The way I transfer this doesn't matter to me, but it might help you out.
        Last edited by SuprSi; 15 Dec 2012, 7:21 PM.
        T11 Asia A after near-fatal bike crash.. Just happy to still be here

        No, I didn't loose my mind... It got scared and ran away!!

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          #34
          they taught us the same. it don't tip when i transfer but i have been leaning down to pick up something and tipped forward.

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            #35
            Originally posted by rollin64 View Post
            they taught us the same. it don't tip when i transfer but i have been leaning down to pick up something and tipped forward.
            Maybe you should consider adding 1'' to your frame depth to avoid this.
            My TR3

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              #36
              Originally posted by Big View Post
              Maybe you should consider adding 1'' to your frame depth to avoid this.
              you're absolutely right. i have a 17" deep chair and don't have that problem at all. i'm wanting my new chair to be short as possible. i'm going 16" with 1/2" longer frame in hopes it'll be pretty stable, plus 80 degree frnt angle.

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