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Thread: Adjusting dump for to compensate for wheel size

  1. #1

    Adjusting dump for to compensate for wheel size

    I have been told that if I get 24" wheels that the wheelchair can be adjusted via amount of dump to get the same effect as 25" rear wheels. Is this true, wont it alter the front angle and hip position? This has come up because sun life only do the natural grip handrims for the quickie helium in size 24" apparently. Should I insist on 25" to ensure the frame is the right size, and get natural grip handrims from another supplier?

  2. #2
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    If it was always possible to adjust a chair so as to make 24"s work like 25"s, no one would use 25"s. If we are talking about reach, then we generally improve that by dropping rear seat height, which you can only do on a chair where this is adjustable and where the chair is not already set as low as it can go. If the chair is already manufactured and in your possession, then, yes, changing rear seat height will affect dump, user posture, and so on, and your ability to compensate may be limited to changing castor size. If the chair is still on the drawing board, then they should be able to compensate for a requested change in rear seat height by adjusting front seat height to preserve the previous dump--but they'll only be able to MAKE that requested drop in RSH if the chair you've requested isn't already at minimum (is it?).

    I'll reiterate that going to larger wheels was the ONLY way I could get satisfactory reach on my highly adjustable Quickie Ti. However, I don't recall you having a reach problem as such, you just seemed to prefer 25"s without quite knowing why. You might quickly get used to 24"s. You could certainly look at getting 25"s and changing the push rims yourself (you'd be looking at about US$300 for Natural Fit LT from SportAid, depending on options, before shipping, and I don't believe VAT applies on wheelchair parts). Or you could get the wheels they're recommending, try them out for a couple of months, and then decide if you still want 25"s, bearing in mind that you may not be able to adjust the chair so that going to the larger wheels aftermarket doesn't throw out your measurements by half an inch. Lastly, you could argue with your rep. If he's taken your order for a chair that includes 25" wheels with Natural Fits, I think either he or the Sunrise/Quickie people should honour that. For what it's worth, when I got my Razorblade it was with the understanding that the rep would keep the brakes that came on it and supply me with third-party ones that worked for me. Perhaps your sales rep could manage something similar. I don't see why you should have to accept a compromise on your daily mobility because a company has chosen not to stock the full range of Natural Fit product.

    Good luck!

  3. #3
    Senior Member ~Lin's Avatar
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    That sounds weird, rsh height (part of dump) is independent of wheel height so it doesn't make sense to say changing your dump will give you the "same effect" as bigger wheels. Bigger wheels are bigger wheels, and dump is dump. Everything works together of course, but it just seems like a bizarre statement to make.

    Now.. flip side... In my chair the rsh has been at the lowest possible since I got the chair. Unfortunately the lowest possible isn't low enough for me. The rule of thumb is with your arms relaxed at your sides your fingertips should fall to the center of the axle. for me, they fall a couple inches above the axle. The performance/functional result of this is that I access less wheel. So, since rsh cannot be changed in my chair I went for bigger wheels and am seeing if this helps. I just got them, so I can't say yet.

    You're ordering a chair, so it doesn't make sense to me that they're trying to talk you out of bigger wheels by talking about the dump. If you already HAD your chair and there was a problem, then yea by all means maybe changing the dump would be your solution as opposed to bigger wheels. But if you want bigger wheels, they work better for you, you liked the 25s, get them on your new chair!

    I have natural fits on my new wheels, and I also happen to have a helium/q7 as well. My new wheels are Katanas from Round Betty, which my DME had never worked with before. They started out by giving me the line I can only get x from sunrise the makers of the q7. It was bull, they just had never gone outside of that before and so didn't know what other options there were. I contacted the owner of Round Betty since he also happens to be a forum member here, and I also went above my seating guys head to send a message to corporate about the situation. Took a little extra time, but I got what I wanted/needed. And a plus side I saved my insurance a bunch of money since my seating guy was going for spinergies.

  4. #4
    FINALLY! I have just spoken to the wheelchair guy and hes going to order me the natural fit handrims in 25" and fit 25" wheels, and contact sunrise to make sure the frame is to the right specs... Phew! I wish I had been firmer earlier on but its so hard when you are not an expert yourself. Hopefully the chair will be great now :) at last I am looking forward to it. What really irritates is when you keep getting told things that are not true. Like the dump being able to compensate for the wheelsize. Or you cant have natural fit rims with spinergy 25", when you can go online and see that they are available. The wheelchair guy has been very pleasant, but it seems to have been a hard process.

  5. #5
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    Sproutbeanie, perhaps I'm a cynic, but having been through the process twice myself and having heard a lot of other people's stories about the process, I'm leaning heavily towards the view that the only time it ISN'T a hard process is when someone else makes all the decisions for you--in which case you'll only get something ideal for you if that person is seriously expert. :-\

    I hope your new chair is great, too. You've certainly been through enough stress organising it!

  6. #6
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    The Q7 doesn't have a lot of adjustability. Rsh is not as adjustable as one might think. Front caster adjustment is good and and axel adjustment is good and back rest adjustment is good but rsh is not that good.

  7. #7
    Senior Member ~Lin's Avatar
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    Quote Originally Posted by QTiPi
    Sproutbeanie, perhaps I'm a cynic, but having been through the process twice myself and having heard a lot of other people's stories about the process, I'm leaning heavily towards the view that the only time it ISN'T a hard process is when someone else makes all the decisions for you--in which case you'll only get something ideal for you if that person is seriously expert. :-\
    For real! I'm so glad I researched before my first ultralight.

    The lowest rsh on the Q7 is 15.5 which is unfortunate, but really not unusual among chairs. Some people have done mods to get lower, I'm thinking about trying that when I get my next chair and this one is backup. Looking I think its possible. Changing the rsh after ordering the chair will change the front frame angle, for example lowering it will increase (I think you guys measure the angle opposite as we do though so maybe decrease as far as numbers for you!). Its a subtle change as long as you got the rsh in the right area when ordering. And of course with changes like that the caster forks need to be squared again.

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