A guy on the New Inventors tonight (Aussie TV show) had a bike rim (adaptable to unicycles) that didn’t have spoke holes. Instead he had a cross section inside the rim. The spokes went through an adapter which then slid in the groove. Between the spoke adapter he had spacers which also slid in the groove, so you could change the number of spokes and the spoke pattern.
He said it was heaps stronger than a normal rim due to no holes.
It suited tubeless rims as the only hole was the valve hole.
Sorry about my poor explanation and lack of drawings, but until then, I was half paying attention to the TV, it was really exciting.
The website says that the rims take upto 220kg loads, does anybody know the loads for trials rims or any other rims for that matter? This could be the way to stop that 26/29" rim from taco-ing… and yet… I am wondering whether this rim would actually make much difference in the side movement commonly experienced in trials unicycling, or even the twisting in street and freestyle. Do any experienced engineers out their have an idea, whether the fact that the rim no longer has holes in it would greatly increase the horizontal stability of the rim, and on a whole, the actual wheel itself???
It’s almost midnight, so this probably makes no sense… goodnight!
I also posted a link from the New Inventors website directly to this thread so that others can see what we were talking about and perhaps the inventor himself will come and talk to this niche in the b*cycle industry (if that is what we are a part of).
On Wed, 17 Aug, ur <> wrote:
>
> I just watched this tonight on ABC…
>
> The website says that the rims take upto 220kg loads, does anybody know
> the loads for trials rims or any other rims for that matter?
A well-built conventional touring-bike wheel will carry lots more than
that, so IF this is supposed to be stronger than a ‘normal’ rim, that
is presumably supposed to be some sort of measure of the strength of
an unlaced rim.
If so, it’s pretty much irrelevant - because that’s not how wheels
work. The combined action of rim and spoke and hub is what matters,
not how one bit behaves on its own. It’s also impossible to compare
with other rims unless they actually define what they mean by “take up
to 220kg loads”.
Regarding side loads, I’d guess it won’t make all that much
difference, because when you’re bending something it’s the material at
teh extremes that contributes most of teh strength. For bending up
and down, avoiding teh spoke holes MIGHT have a significant effect,
because the holes are at the extreme (top) of the section. Bending
sideways, teh holes are half-way across teh section, and material
there will not be nearly as effective, so taking it out or putting it
back will be not nearly as significant.
But I haven’t seen teh section, just the description posted here.
It seems very unlikely that this modification makes a significant difference to the strength of the wheel. The strength of a wheel comes from the spoke tension, not the rim material; the strength of the rim material matters only insofar as it’s required to support a high level of spoke tension. From the looks of it, this system would not be able to support as high a level of spoke tension as a good rim (those inserts look like they’d want to pull out).
It says 220kg spoke load. Maybe they mean the spoke tension in Kgf, which is what spoke tension meters measure. I’m not sure what that means and how that relates to the weight a wheel can take, but that’s well above the amount normal wheels are built to, which is only up to 150 or so according to Mr Park Tools.
It is an interesting idea because of the ability to have different numbers of spokes.
It won’t make the rim lighter, because it has a continuous spoke-rim interface, rather than selectively placed ones.
It also won’t support higher tension, one of the primary aspects of wheel strength. The limiting factor in spoke tension, for the better rims, is not hole strength, but brace angle and the rim’s torsional stiffness. These attributes are unaffected by the new idea.
Additionally, it appears to make replacing a nipple/spoke impossible without rebuilding the entire wheel. This is a no-go item in my mind.
It multiplies the number of parts required to build a wheel.
The only real advantage I see is that it allows the nipple to pivot to follow the spoke line, but this is not much of an advantage for larger wheels, especially 3x.
According to a brief read of the web site linked above, the purpose of this design is to prevent air leaking through the spoke holes when using tubeless tires. The benefits for “regular” tires may not be as apparent.
It looks like the inserts hold a nipple in them, so you may be able to unscrew a broken spoke from the nipple and rescrew in a new one. Maybe without the bend at the nipple, you’ve got less chance of breaking that end of the spoke than at the hub. Supposedly the load is spread over a larger area of the rim by the way the spokes are attached, does that make any difference?
This benefit is deceptive; the proper rim strip does just as well with the advantage of being much lighter than the corresponding metal.
But how do you get the inserts out to change a nipple?
Actually the bend for a typical 700c wheel is very very slight anyway. And that’s not where spokes break, they break at the 90 degree bend near the head, due to fretting, usually from an undertensioned wheel.
Normal good-quality rims have either thickened metal around the spoke hole, or make use of eyelets, which both accomplish the same thing. Ditto for the wide-flange nipples I use on the Coker wheels.
An interesting concept for spoke attachment, though I’ve seen similar methods for attaching other stuff (that works well), but there’s not nearly enough information for anything other than a cursory evaluation. I guess they won’t want to give to much info out (patent pending). I’ve always considered the traditional method of spoke to rim and spoke to hub attachment, though perfectly functional, a little antiquated.
New ideas are great. Some of them make a lot of money. A very, very few of them stand the test of time. Many ideas that do not last, make a lot of money anyway because people buy something that is “different”.
In this case, the inventor appears to be trying to solve a problem that either 1) does not exist, or 2) only exists for manufacturers. In this implementation, it appears to add several disadvantages to the user.
It may be a stepping-stone to other implementations that revolutionize the bicycle wheel. Or, it may be yet another dead end. Or, it may spark yet another idea in the inventor’s or someone else’s mind.
My post above was intended neither to ridicule, oppose, or honor. It was me trying to analyze the invention from a technical point of view based on scanty evidence. If you send me the money, I’ll build you a wheel using one of those rims - if they are available as rims only!
Yes, I think the only immediately significant benefit is that it eliminates the secondary operation of drilling the spoke holes in the extrusion before it is rolled into a rim. It will roll more smoothly without holes also. Both of those things benefit the manufacturer.
At first the idea of being easier to seal for tubeless sounds great. But, as Dave said, I think rim strips do a good job of that. The biggest leakage problems seem to be at the tire bead.
It may catch on but it will start with the most popular sizes in the bicycle market, most of which we don’t use anyway.
