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Thread: 24 to 25" rear wheels make chair tippier?

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  1. #1

    24 to 25" rear wheels make chair tippier?

    per: question of thread. will going to bigger wheels make chair any tippier or vice-versa, make it less?

    any ideas? this is with everything else being the same. casters, cog etc.

  2. #2
    Bigger wheels will reduce dump (possible even introduce negative dump, ie, you're sliding forward), and will make it harder to do wheelies (ie, reduce tippiness). They may (will) also cause your castors to be out of alignment (ie, the caster housing will no longer be perpendicular to the ground).

  3. #3
    I have a hunch larger wheels will alter cog as well. That + reduced dump will def put you on your face and/or skull, I'd imagine. Can you adjust cog or dump? I never do but I like knowing it's an option!

  4. #4
    24 to 25 is a half inch on top and on the bottom unless you change tire types. It could be nearly the same or much more. Run the back of your chair up and take a look/feel.
    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. #5
    Going from 24 to 25 will raise the back of your chair by 1/2". It will alter the dump/cog unless your axle mounting brackets accommodate various wheel sizes. Similarly, your front wheel forks will be tilted and probably affect turning. It will put the rims closer to your shoulder so you will have less distance to reach when you wheel. I had 26" wheels on a chair built for them and loved them except for the fact that it made transferring on and off more difficult. Tipiness is a function of cog setting and wheel size alone does not affect that.
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  6. #6
    Senior Member wheeliecoach's Avatar
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    Quote Originally Posted by SCIfor55yrs. View Post
    Going from 24 to 25 will raise the back of your chair by 1/2". It will alter the dump/cog unless your axle mounting brackets accommodate various wheel sizes. Similarly, your front wheel forks will be tilted and probably affect turning. It will put the rims closer to your shoulder so you will have less distance to reach when you wheel. I had 26" wheels on a chair built for them and loved them except for the fact that it made transferring on and off more difficult. Tipiness is a function of cog setting and wheel size alone does not affect that.
    Totally agree...while I lost some dump when I put a bigger wheel on my chair where the dump was not adjustable, I was not more tippy because of it. The cog is what makes the chair more tippy...not the wheel size.
    "Unless someone like you cares a whole awful lot nothing's going to get better. It's not." - Dr. Seuss

  7. #7
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    If only raise height of rear wheels by 1/2" you will increase tipping forward. If you move your butt forward on seat, you WILL change COG and increase chance of tipping out of chair FORWARD.

    Quote Originally Posted by wheeliecoach View Post
    Totally agree...while I lost some dump when I put a bigger wheel on my chair where the dump was not adjustable, I was not more tippy because of it. The cog is what makes the chair more tippy...not the wheel size.

  8. #8
    Senior Member wheeliecoach's Avatar
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    Quote Originally Posted by rlmtrhmiles View Post
    If only raise height of rear wheels by 1/2" you will increase tipping forward. If you move your butt forward on seat, you WILL change COG and increase chance of tipping out of chair FORWARD.
    OK...see your point...but I usually wheel with my butt back in my seat...not forward. All relative I guess...but even with smaller wheels I could fall over if I sit more forward in my seat.
    "Unless someone like you cares a whole awful lot nothing's going to get better. It's not." - Dr. Seuss

  9. #9
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    YEPPERS!!!! You will need to learn to control your upper body, and you better doing it darn fast. EVERYTHING said here, exactly true. With that learned control, you WILL have tremendous gain. I went 24" to 26". Chair CAN BE designed such that you are sitting in same realtive location. Did you try a bigger wheel? That may be a good idea and see what will happen.

  10. #10
    Quote Originally Posted by rollin64 View Post
    per: question of thread. will going to bigger wheels make chair any tippier or vice-versa, make it less?

    any ideas? this is with everything else being the same. casters, cog etc.
    If your RSH is not adjustable going for a 559 will raise your RSH, so you will have less dump, that makes the chair less tippy.
    Will affect to the forks angle a bit too, but that will not be a problem if you don`t go like Speedy Gonzales in your wheelchair .
    Will affect to your backrest angle a bit too, etc.

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