Rolling Resistance + chair design

[Bear_on_wheels]

As my health is getting worse, I've become increasingly interested (obsessed?!) with rolling resistance.

Is there anyone here who cares to discuss how wheelchair design affects rolling resistance?

I've found that some of the cheapest chairs I have owned/tried have far less rolling resistance than very expensive chairs.

I've tried installing brand new, high quality bearings and wheels. Tried altering cog, camber, toe in toe out. Castor fork angle. Tried swapping forks and wheels with other chairs that roll more easily.

But still I find that one of my most expensive chairs (referring to market price) is so hard to push, I just had to give up on it.

And one of my cheapest chairs, with no new components, just what it came with 2nd hand, is by far the easiest to push. You can turn the wheel with just one finger on the rim!

What is it about this chair that makes it so easy to push?

And, if anyone cares to post about which chairs they have found have v low rolling resistance, and which had high, that'd be great

[baldfatdad]

I have a 30 year old Quickie folder that I won't give up because it rolls so well. How do you check your chairs for rolling resistance? I use a digital fish scale and I have marks on a hill on a road that I roll down and time.
Have you checked the toe on the chair that pushes hard? That is one of the biggys for rolling resistance.

[nonoise]

Here are some puzzlements of mine along this same line of thought.
I did not get the improvement I expected installing new bearings in 24 inch quickie wheels.

Brand new 26 inch quickie wheels seem as slippery as new Spineries, oh my oh my what I just said! I haven't done side by side comparison.

Old 24 inch Colours wheels on it's own chair on smooth surface are fast, but on concrete something makes it drag. I suspect the caster bearings. The toe in and caster angle measure perfect on the rear wheels. I'm going to switch out the caster wheels with razor wheels and see what happens.

Of course we are supposed to keep weight off the casters as much as possible, but I've wondered if caster size matters. I've seen some pros wheeling mighty fast with tiny caster wheels.

My current go places outdoors chair is a quickie 2, spinergies, Marathon plus (only 100psi, that's all wife could get in them), and new Ki mobility casters. I'm happy with it.

[SCI_OTR]

The majority of rolling resistance occurs at the front casters. The variables at play from a wheelchair design standpoint include caster diameter, tire type, contact area, and (to some degree) bearing alignment. The bearings themselves are less significant.

Issues related to the user/environment/wheelchair configuration play a much larger role than design issues. Specifically, what is the users's weight, how much of it is being distributed over the front casters, what type of surface is being traversed, and what types of slopes are associated with the path that the wheelchair is taking.

An old Quickie 2 with a posterior located axle will be easier to push in a straight path across thick carpet when using an 8" caster than would be the case if it had 4x1.5" FrogLegs aluminum hub soft rolls. Going across the kitchen floor, however, the convex shape and harder compound of the FLAHSR tire will be easier to push.

The larger diameter of the 8" caster does better over more-irregular surfaces that have a higher coefficient of friction. The convex shape of the tire and precise bearing alignment of a 4x1.5 aluminum hub soft roll caster does better on a hard smooth surfaces because it has less contact area and the bearings are more precisely aligned (due to the milled hub). For most people, this type of caster is better suited for the everyday environments in which they normally use their wheelchair. It will perform even better iwhen the rear axle is located further forward because the user's weight would be shifted off of the casters and over the rear wheels (which overcome rolling resistance much more-easily due to their much larger diameter).

When I think about rolling resistance, I ask myself "Why does the FreeWheel work so well?" It works so well because it is usually attached to a chair that has probably been dialed in for biomechanically efficient propulsion using smaller casters. The FreeWheel decreases overall rolling resistance by eliminating resistance at the two casters by replacing them with a single wheel having well over twice the diameter without altering a biomechanically efficient configuration.

[voxina]

I'm with SCI OTR on the casters deal. If your front casters are tiny, say 3 in, it could be it's not set up for your environment. I've seen in using chairs that a 4 in caster is much more difficult to push on soft surfaces, eg, carpet, than are the larger variety. I'd totally try putting on larger casters on the higher end chairs you have, see if that helps. It should. And definitely the toe-in toe-out, and make sure your spacers are right, that can cause massive resistance, and also if there's anything that could be protruding and rubbing your wheels/something dragging. I know that sounds really obvious but it's happened with me before, as well, with the side guards and/or armrests touching/rubbing the wheels, was a big pain.

[baldfatdad]

Check the toe with you sitting in it. Folders move when you load the frame.
Check the spoke tune and the true of the rim. The rear bearings have to be a rust heap with no grease to hurt the push. You are only turning them once in 6 feet.
Like Sci Otr says the worse the surface the bigger the front wheel helps. The firmer the surface the small wheel will work better.
Are your caster forks free to swivel? Do your heels drag on soft surfaces?

[Bear_on_wheels]

Thank you all for the responses

Forgot to mention-
The two chairs I am referring to are:
1) Remploy ''Veloce'' - low quality overall esp. parts, but amazingly low rolling resistance.
2) Colours ''Zephyr'' - Excellent quality but awfully high rolling resistance.

So I'm trying to work out, what makes the Veloce so easy to push, and the Zephyr so hard?

Re-toe in toe out-
The Zephyr uses a camber bar and a disc system that I've not seen before. Seems like there is little room for adjustment.
It was custom made, but bought 2nd hand. However, no chair custom or not should be built to be hard to push.

I've tried adjusting toe in, toe out. Doesn't make much difference. The main resistance seems to be coming from the front of the frame, i.e the castors.

But even when I swap castors, and even forks, with chairs that are easy to push, the Zephyr remains at least 3x harder to push than the Veloce.

What I reckon-
So far I've concluded that it's something to do with the frame shape/dimensions or weight distribution?

Plans-
If I can work out exactly what's wrong, I'm hoping to be able to get the frame cut and the castors moved using a local welder.

I'm going to try and upload some pics of them both to make it easier to show stuff.

[Bear_on_wheels]

Originally Posted by baldfatdad

I have a 30 year old Quickie folder that I won't give up because it rolls so well. How do you check your chairs for rolling resistance? I use a digital fish scale and I have marks on a hill on a road that I roll down and time.
Have you checked the toe on the chair that pushes hard? That is one of the biggys for rolling resistance.

Hi BaldFatDad (like the username ,

No I'm not as scientific as you when it comes to measuring rolling resistance. I just go by feel.

Will google Fish scale though, thanks for the tip

Re-Toe in/out.
Yes, that was one of the first things I tried to adjust. The Colours Zephyr that has such high rolling resistance was a custom build, ex-demo. Only way I can afford such chairs.
It uses a camber bar with a kind of disc that you can rotate clockwise/anti. But you can only rotate it about 1 hour on the clock face.

It's also very fiddly and difficult to get each wheel the same, esp. when working on your own. For some annoying reason, the camber disc has been designed so that you always have some toe in or out.

So far I've found it impossible to get no toe at all :/ User manual no help, not anywhere detailled enough re-such adjustments.

Re-Castor forks
Yeah the main resistance seems to be coming from the front of the chair. The forks are free to swivel, though they were done up too tight when I first got it. It's an ex-demo, so likely spend years with too tight forks.
Loosening them did make them swivel much more freely, but disappointed to find the rolling resistance not that much reduced :/

Re-Heels dragging
Sorry I have no idea what you mean?



Toe in is much better than toe out for reducing rolling resistance right?
And no toe is best of all?

[Bear_on_wheels]

Originally Posted by baldfatdad

I have a 30 year old Quickie folder that I won't give up because it rolls so well. How do you check your chairs for rolling resistance? I use a digital fish scale and I have marks on a hill on a road that I roll down and time.
Have you checked the toe on the chair that pushes hard? That is one of the biggys for rolling resistance.

Hi BFD I finally found the spare energy to check out fish scales, but am more confused.

A fish scale seems to be a device for measuring the weight of fish. So, how do you use one to measure rolling resistance?

[baldfatdad]

You can measure rolling resistance with the fish scale by hooking the scale to the foot rest and pulling the chair. Read the weight on the scale. It is telling you how much effort it takes to move the chair.
Check to see if the heels of your feet/shoes hang below the foot rest and drag on the carpet. In deep carpet I can see the marks my shoes leave.